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Gut microbiome composition is tied to diseases ranging from arthritis to cancer to depression. However, mechanisms of action are poorly understood, limiting development of relevant therapeutics. Organ‐on‐chip platforms, which model minimal functional units of tissues and can tightly control communication between them, are ideal platforms to study these relationships. Many gut microbiome models are published to date but devices are typically fabricated using oxygen permeable polydimethylsiloxane, requiring interventions to support anaerobic bacteria. To address this challenge, a platform is developed where the chips are fabricated entirely from gas‐impermeable polycarbonate without tapes or gaskets. These chips replicate polarized villus‐like structures of the native tissue. Further, they enable co‐cultures of commensal anaerobic bacteria Blautia coccoides on the surface of gut epithelia for two days within a standard incubator. Another complication of commonly used materials in organ‐on‐chip devices is high ad‐/absorption, limiting applications in high‐resolution microscopy and biomolecule interaction studies. For future communication studies between gut microbiota and distal tumors, an additional polycarbonate chip design is developed to support hydrogel‐embedded tissue culture. These chips enable high‐resolution microscopy with all relevant processing done on‐chip. Designed for facile linking, this platform will make a variety of mechanistic studies possible. [ABSTRACT FROM AUTHOR]

Background and Purpose: This study analyses whether first‐line antihypertensive drugs ameliorate the dysbiosis state in hypertension, and to test if this modification contributes to their blood pressure (BP) lowering properties in a genetic model of neurogenic hypertension. Experimental Approach: Twenty‐week‐old male Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were untreated or treated with captopril, amlodipine or hydrochlorothiazide. A faecal microbiota transplantation (FMT) experiment was also performed by gavage of faecal content from donor SHR‐treated groups to SHR recipients for 3 weeks. Key results: Faeces from SHR showed gut dysbiosis, characterized by lower acetate‐ and higher lactate‐producing bacteria and lower strict anaerobic bacteria. All three drugs increased the anaerobic bacteria proportion, captopril and amlodipine restored the proportion of acetate‐producing bacterial populations to WKY levels, whereas hydrochlorothiazide decreased butyrate‐producing bacteria. Captopril and amlodipine decreased gut pathology and permeability and attenuated sympathetic drive in the gut. Both drugs decreased neuroinflammation and oxidative stress in the hypothalamic paraventricular nuclei. Hydrochlorothiazide was unable to reduce neuroinflammation, gut sympathetic tone and gut integrity. FMT from SHR‐amlodipine to SHR decreased BP, ameliorated aortic endothelium‐dependent relaxation to acetylcholine, lowered NADPH oxidase activity, aortic Th17 infiltration and reduced neuroinflammation, whereas FMT from SHR‐hydrochlorothiazide did not have these effects. Conclusions and Implications: First‐line antihypertensive drugs induced different modifications of gut integrity and gut dysbiosis in SHR, which result in no contribution of microbiota in the BP lowering effects of hydrochlorothiazide, whereas the vasculo‐protective effect induced by amlodipine involves gut microbiota reshaping and gut‐immune system communication. [ABSTRACT FROM AUTHOR]

Coculture of intestinal bacteria with primary human intestinal epithelium provides a valuable tool for investigating host‐colon bacterial interactions and for testing and screening therapeutics. However, most current intestinal model systems lack key physiological features of the in vivo colon, such as both a proper oxygen microenvironment and a mucus layer. In this work, a new in vitro colonic microphysiological system is demonstrated with a cell‐derived, functional mucus that closely resembles the in vivo colonic mucosa and apical microenvironment by employing an anaerobic air‐liquid interface culture. The human primary colon epithelial cells in this new in vitro system exhibit high cell viability (>98%) with ≈100 µm thick functional mucus layer on average. Successful coculture of model anaerobic gut bacterial strains Lactobacillus rhamnosus GG and Anaerobutyricum hallii without loss in human cell viability demonstrates that this new model can be an invaluable tool for future studies of the impact of commensal and pathogenic bacteria on the colon. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis is a gram‐negative anaerobic bacterium recognized for its pivotal role in the pathogenesis of periodontal diseases. This review covers an overview of the virulence factors and lifecycle stages of P. gingivalis, with a specific focus on attachment and colonization, biofilm formation, growth and multiplication, dormancy survival and dissemination. Additionally, we explore the significance of inter‐bacterial cross‐feeding within biofilms. Furthermore, we discuss potential phytochemical‐based strategies to target P. gingivalis, including the use of curcumin, apigenin, quercetin and resveratrol. Understanding the virulence factors and lifecycle stages of P. gingivalis, along with the promising phytochemical‐based interventions, holds promise for advancing strategies in periodontal disease management and oral health promotion. [ABSTRACT FROM AUTHOR]

Fusobacterium nucleatum, a gram‐negative anaerobic bacterium abundantly found in the human oral cavity, is widely recognized as a key pathobiont responsible for the initiation and progression of periodontal diseases due to its remarkable aggregative capabilities. Numerous clinical studies have linked F. nucleatum with unfavorable prognostic outcomes in various malignancies. In further research, scholars have partially elucidated the mechanisms underlying F. nucleatum's impact on various types of cancer, thus gaining a certain comprehension of the role played by F. nucleatum in cancer. In this comprehensive review, we present an in‐depth synthesis of the interplay between F. nucleatum and different cancers, focusing on aspects such as tumor initiation, metastasis, chemoresistance, and modulation of the tumor immune microenvironment and immunotherapy. The implications for cancer diagnosis and treatment are also summarized. The objective of this review is to enhance our comprehension of the intricate relationship between F. nucleatum and oncogenic pathogenesis, while emphasizing potential therapeutic strategies. [ABSTRACT FROM AUTHOR]

Infection is among the most common factors that impede wound healing, yet standard treatments routinely fail to resolve chronic wound infections. The chronic wound environment is largely hypoxic/anoxic, and wounds are predominantly colonised by facultative and obligate anaerobic bacteria. Oxygen (O2) limitation is an underappreciated driver of microbiota composition and behaviour in chronic wounds. In this perspective article, we examine how anaerobic bacteria and their distinct physiologies support persistent, antibiotic‐recalcitrant infections. We describe the anaerobic energy metabolisms bacteria rely on for long‐term survival in the wound environment, and why many antibiotics become less effective under hypoxic conditions. We also discuss obligate anaerobes, which are among the most prevalent taxa to colonise chronic wounds, yet their potential roles in influencing the microbial community and wound healing have been overlooked. All of the most common obligate anaerobes found in chronic wounds are opportunistic pathogens. We consider how these organisms persist in the wound environment and interface with host physiology to hinder wound healing processes or promote chronic inflammation. Finally, we apply our understanding of anaerobic physiologies to evaluate current treatment practices and to propose new strategies for treating chronic wound infections. [ABSTRACT FROM AUTHOR]

The intricate relationship between regeneration and microbiota has recently gained attention, spanning diverse model organisms. Axolotl (Ambystoma mexicanum) is a critically endangered salamander species and a model organism for regenerative and developmental biology. Despite its significance, a noticeable gap exists in understanding the interplay between axolotl regeneration and its microbiome. Here, we analyse in depth bacterial 16S rRNA amplicon dataset that we reported before as data resource and profile fungal community by sequencing ITS amplicons at the critical stages of limb regeneration (0–1–4–7–30–60 days post amputation, ‘dpa’). Results reveal a decline in richness and evenness in the course of limb regeneration, with bacterial community richness recovering beyond 30 dpa unlike fungi community. Beta diversity analysis reveals precise restructuring of the bacterial community along the three phases of limb regeneration, contrasting with less congruent changes in the fungal community. Temporal dynamics of the bacterial community highlight prevalent anaerobic bacteria in initiation phase and Flavobacterium bloom in the early phase correlating with limb blastema proliferation. Predicted functional analysis mirrors these shifts, emphasising a transition from amino acid metabolism to lipid metabolism control. Fungal communities shift from Blastomycota to Ascomycota dominance in the late regeneration stage. Our findings provide ecologically relevant insights into stage specific role of microbiome contributions to axolotl limb regeneration. [ABSTRACT FROM AUTHOR]

The potential involvement of the gut microbiota in metabolic dysfunction‐associated steatohepatitis (MASH) pathogenesis has garnered increasing attention. In this study, we elucidated the link between high‐fat/cholesterol/cholate‐based (iHFC)#2 diet‐induced MASH progression and gut microbiota in C57BL/6 mice using antibiotic treatments. Treatment with vancomycin (VCM), which targets gram‐positive bacteria, exacerbated the progression of liver damage, steatosis, and fibrosis in iHFC#2‐fed C57BL/6 mice. The expression levels of inflammation‐ and fibrosis‐related genes in the liver significantly increased after VCM treatment for 8 weeks. F4/80+ macrophage abundance increased in the livers of VCM‐treated mice. These changes were rarely observed in the iHFC#2‐fed C57BL/6 mice treated with metronidazole, which targets anaerobic bacteria. A16S rRNA sequence analysis revealed a significant decrease in α‐diversity in VCM‐treated mice compared with that in placebo‐treated mice, with Bacteroidetes and Firmicutes significantly decreased, while Proteobacteria and Verrucomicrobia increased markedly. Finally, VCM treatment dramatically altered the level and balance of bile acid (BA) composition in iHFC#2‐fed C57BL/6 mice. Thus, the VCM‐mediated exacerbation of MASH progression depends on the interaction between the gut microbiota, BA metabolism, and inflammatory responses in the livers of iHFC#2‐fed C57BL/6 mice. [ABSTRACT FROM AUTHOR]

Introduction: In chronic rhinosinusitis (CRS), the congestion and blockage of the nose can cause anaerobic conditions within the sinus cavities which may promote the expression of virulence and antibiotic resistance genes in invading pathogens. Pseudomonas aeruginosa is a facultative anaerobic bacteria and causes severe recalcitrant CRS. In this study, we aimed to evaluate the antimicrobial resistance of P. aeruginosa isolates of CRS patients in planktonic and biofilm form grown in aerobic and anaerobic conditions. Methods: P. aeruginosa clinical isolates of CRS patients (n = 25) were grown in planktonic and biofilm form in aerobic and anaerobic conditions. Minimum inhibitory concentrations (MIC) of planktonic forms and minimum biofilm eradication concentrations (MBEC) were determined. Additionally, metabolic activity by fluorescein diacetate assay, biofilm biomass by crystal violet assay and eDNA concentration were assessed in both conditions. Results: P. aeruginosa planktonic cells grown in anaerobic condition exhibited increased gentamicin resistance (p < .01), whereas P. aeruginosa biofilms grown in anaerobic condition displayed significantly increased MBEC values for gentamicin (p < .0001) and levofloxacin (p < .001). The metabolic activity of anaerobic biofilms was significantly higher compared with aerobic biofilms (p < .0001). However, the biofilm biomass of isolates grown in aerobic conditions was higher than anaerobic conditions (p < .5). Conclusion: P. aeruginosa isolates from CRS patients grown in anaerobic conditions showed significantly increased resistance to antibiotics with an increased metabolic activity but decreased biofilm biomass. [ABSTRACT FROM AUTHOR]

Morganella morganii is a gram negative, facultative anaerobic rod‐shaped bacterium, commonly found in environment and in the intestine of human, mammals, and reptiles as a part of their gut microbiome. M. morganii can cause Gram‐negative folliculitis, black nail infection, acute retiform purpura, fetal demise, and subdural empyema. The increasing frequency of M. morganii infections generate the need for efficient methods to enrich the presence of M. morganii in clinical samples to make its detection easier. Culturomics aims to grow and maximize the number of culturable bacteria. Different methods are followed to maximize the growth of minority population of bacteria by disrupting the growth of bacteria which are present in higher concentration. This article presents a method for selective enriching the M. morganii in human fecal samples. This method includes prior incubation of fecal microbiota in an anaerobic environment, adding supplement like fecal water to give dormant bacteria a break to become active to grow to threshold concentration, and an enrichment stage which provides the additional opportunity of growing to M. morganii on the selective medium. This method also provides an ingenuous way for augmenting the growth of fecal M. morganii species. Significance statement: Morganella morganii can cause Gram‐negative folliculitis, black nail infection, acute retiform purpura, fetal demise, and subdural empyema. The increasing frequency of M. morganii infections generate the need for efficient methods to enrich the presence of M. morganii in clinical samples to make its detection easier. Different methods are followed to maximize the growth of a minority population of bacteria by disrupting the growth of bacteria which are present in higher concentration. Our research work developed a method which includes prior incubation of fecal microbiota in an anaerobic environment, adding supplement like fecal water to give dormant bacteria a break to become active to grow to threshold concentration, and an enrichment stage which provides the additional opportunity of growing to M. morganii on the selective medium. [ABSTRACT FROM AUTHOR]

Flavodiiron proteins (FDPs) are a family of enzymes with a significant role in O2/H2O2 and/or NO detoxification through the reduction of these species to H2O or N2O, respectively. All FDPs contain a minimal catalytic unit of two identical subunits, each one having a metallo‐β‐lactamase‐like domain harboring the catalytic diiron site, and a flavodoxin‐like domain. However, more complex and diverse arrangements in terms of domains are found in this family, of which the class H enzymes are among the most complex. One of such FDPs is encoded in the genome of the anaerobic bacterium Syntrophomonas wolfei subsp. wolfei str. Goettingen G311. Besides the core domains, this protein is predicted to have three additional ones after the flavodoxin core domain: two short‐chain rubredoxins and a NAD(P)H:rubredoxin oxidoreductase‐like domain. This enzyme, FDP_H, was produced and characterized and the presence of the predicted cofactors was investigated by a set of biochemical and spectroscopic methodologies. Syntrophomonas wolfei FDP_H exhibited a remarkable O2 reduction activity with a kcat = 52.0 ± 1.2 s−1 and a negligible NO reduction activity (~ 100 times lower than with O2), with NADH as an electron donor, that is, it is an oxygen‐selective FDP. In addition, this enzyme showed the highest turnover value for H2O2 reduction (kcat = 19.1 ± 2.2 s−1) ever observed among FDPs. Kinetic studies of site‐directed mutants of iron‐binding cysteines at the two rubredoxin domains demonstrated the essential role of these centers since their absence leads to a significant decrease or even abolishment of O2 and H2O2 reduction activities. [ABSTRACT FROM AUTHOR]

A dysbiotic microbial community whose members have specific/synergistic functions that are modulated by environmental conditions, can disturb homeostasis in the subgingival space leading to destructive inflammation, plays a role in the progression of periodontitis. Filifactor alocis, a gram‐positive, anaerobic bacterium, is a newly recognized microbe that shows a strong correlation with periodontal disease. Our previous observations suggested F. alocis to be more resistant to oxidative stress compared to Porphyromonas gingivalis. The objective of this study is to further determine if F. alocis, because of its increased resistance to oxidative stress, can affect the survival of other 'established' periodontal pathogens under environmental stress conditions typical of the periodontal pocket. Here, we have shown that via their interaction, F. alocis protects P. gingivalis W83 under H2O2‐induced oxidative stress conditions. Transcriptional profiling of the interaction of F. alocis and P. gingivalis in the presence of H2O2‐induced stress revealed the modulation of several genes, including those with ABC transporter and other cellular functions. The ABC transporter operon (PG0682–PG0685) of P. gingivalis was not significant to its enhanced survival when cocultured with F. alocis under H2O2‐induced oxidative stress. In F. alocis, one of the most highly up‐regulated operons (FA0894–FA0897) is predicted to encode a putative manganese ABC transporter, which in other bacteria can play an essential role in oxidative stress protection. Collectively, the results may indicate that F. alocis could likely stabilize the microbial community in the inflammatory microenvironment of the periodontal pocket by reducing the oxidative environment. This strategy could be vital to the survival of other pathogens, such as P. gingivalis, and its ability to adapt and persist in the periodontal pocket. [ABSTRACT FROM AUTHOR]

Current microbiome investigations of patients with pressure ulcers (PU) are mainly based on wound swabs and/or biopsy sequencing, leaving the colonization scenario unclear. Urinary microbiota has been never studied. As a part of the prospective ESCAFLOR study, we studied urinary microbiota of spinal cord injury (SCI) patients with PU without any urinary tract infection at the inclusion, collected at two times (at admission [D0] and after 28 days [D28]) during the patient's care, investigated by 16S rDNA metagenomics next generation sequencing. Subgroup analyses were carried out between patients with wounds showing improved evolution versus stagnated/worsened wounds at D28. Analysis was done using EPISEQ® 16S and R software. Among the 12 studied patients, the urinary microbiota of patients with improved wound evolution at D28 (n = 6) presented a significant decrease of microbial diversity. This modification was associated with the presence of Proteobacteria phylum and an increase of Escherichia‐Shigella (p = 0.005), as well as the presence of probiotic anaerobic bacteria Lactobacillus and Bifidobacterium. In contrast, Proteus abundance was significantly increased in urine of patients with stagnated/worsened wound evolution (n = 6) (p = 0.003). This study proposes urinary microbiota as a complementary factor indirectly associated with the wound evolution and patient cure. It opens new perspectives for further investigations based on multiple body microbiome comparison to describe the complete scenario of the transmission dynamics of wound‐colonizing microorganisms. [ABSTRACT FROM AUTHOR]

Aim: The gut microbiota has been reported to be associated with acute graft‐versus‐host disease (aGvHD) in hematopoietic stem cell transplantation (HSCT). Dynamic surveillance of the microbiota is required to understand the detailed pathogenesis involved in the process of aGvHD. Methods: Fecal samples were collected prospectively at four timepoints, including pre‐HSCT (T1), graft infusion (T2), neutrophil engraftment (T3), and 30 days after transplantation (T4). Fecal samples were profiled by 16S ribosomal RNA gene sequencing to assess the microbiota composition. Results: From the T1 to T4 timepoint, the diversity of the gut microbiota decreased, and the dominant species also changed, with a decrease in the obligate anaerobic bacteria and a shift toward a "pathogenic community". Compared with non‐aGvHD patients, aGvHD patients had a lower abundance of Roseburia at T1 and a higher abundance of Acinetobacter johnsonii at T2. Furthermore, Acinetobacter johnsonii was negatively correlated with the secretion of IL‐4 and TNF‐α. At T3, Rothia mucilaginos was demonstrated to be linked with a decreased risk of aGvHD, which was accompanied by decreased secretion of IL‐8. At T4, higher abundances of Lactobacillus paracasei and Acinetobacter johnsonii were identified to be related with aGvHD. Lactobacillus paracasei was associated with the downregulation of IL‐10, and Acinetobacter johnsonii was associated with the downregulation of IL‐2 and TNF‐α. Conclusions: Dynamic changes in gut microbiota composition and related cytokines were found to be related to aGvHD, including pathogenic or protective changes. These findings suggested that manipulation of gut microbiota at different timepoints might be a promising avenue for preventing or treating this common complication. [ABSTRACT FROM AUTHOR]

Candida albicans is frequently identified as a colonizer of the oral cavity in health and has recently been termed a "keystone" commensal due to its role on the bacterial communities. However, the role that C. albicans plays in such interactions is not fully understood. Therefore, this study aimed to identify the relationship between C. albicans and bacteria associated with oral symbiosis and dysbiosis. To do this, we evaluated the ability of C. albicans to support the growth of the aerobic commensal Streptococcus gordonii and the anaerobic pathogens Fusobacterium nucleatum and Porphyromonas gingivalis in the biofilm environment. RNA‐Sequencing with the Illumina platform was then utilized to identify C. albicans gene expression and functional pathways involved during such interactions in dual‐species and a 4‐species biofilm model. Results indicated that C. albicans was capable of supporting growth of all three bacteria, with a significant increase in colony counts of each bacteria in the dual‐species biofilm (p < 0.05). We identified specific functional enrichment of pathways in our 4‐species community as well as transcriptional profiles unique to the F. nucleatum and S. gordonii dual‐species biofilms, indicating a species‐specific effect on C. albicans. Candida‐related hemin acquisition and heat shock protein mediated processes were unique to the organism following co‐culture with anaerobic and aerobic bacteria, respectively, suggestive that such pathways may be feasible options for therapeutic targeting to interfere with these fungal‐bacterial interactions. Targeted antifungal therapy may be considered as an option for biofilm destabilization and treatment of complex communities. Moving forward, we propose that further studies must continue to investigate the role of this fungal organism in the context of the interkingdom nature of oral diseases. [ABSTRACT FROM AUTHOR]

Phosphite is a stable phosphorus compound that, together with phosphate, made up a substantial part of the total phosphorus content of the prebiotic Earth's crust. Oxidation of phosphite to phosphate releases electrons at an unusually low redox potential (−690 mV at pH 7.0). Numerous aerobic and anaerobic bacteria use phosphite as a phosphorus source and oxidise it to phosphate for synthesis of nucleotides and other phosphorus‐containing cell constituents. Only two pure cultures of strictly anaerobic bacteria have been isolated so far that use phosphite as an electron donor in their energy metabolism, the Gram‐positive Phosphitispora fastidiosa and the Gram‐negative Desulfotignum phosphitoxidans. The key enzyme of this metabolism is an NAD+‐dependent phosphite dehydrogenase enzyme that phosphorylates AMP to ADP. These phosphorylating phosphite dehydrogenases were found to be related to nucleoside diphosphate sugar epimerases. The produced NADH is channelled into autotrophic CO2 fixation via the Wood‐Ljungdahl (CO‐DH) pathway, thus allowing for nearly complete assimilation of the substrate electrons into bacterial biomass. This extremely efficient type of electron flow connects energy and carbon metabolism directly through NADH and might have been important in the early evolution of life when phosphite was easily available on Earth. [ABSTRACT FROM AUTHOR]

Identifying the microbiome within chronic diabetic foot ulcers is essential if effective antimicrobial therapies are to be administered. Using culture and 16S rRNA gene sequencing, the aim of this study was to compare the microbiome of paired tissue scraping samples with swab samples, collected from participants during attendance at a high‐risk foot clinic. The mean richness of cultured swab and tissue scraping samples was consistent, with anaerobes infrequently isolated from both sample types. Comparing percentage frequencies of detection of selected genera of known and potential pathogens namely Staphylococcus, Streptococcus, Enterococcus, Corynebacterium, Enterobacteriaceae and Pseudomonas from cultured and sequenced swab and tissue scrapings indicated that both collection methods captured varying percentages of all the selected genera. The mean abundance of sequenced samples was not significantly different between swabs and tissue scrapings. The mean richness or number of distinct operational taxonomic units (OTUs) and Shannon's H diversity index were not significantly different between the two collection methods. The mean relative abundance of the selected genera of known and potential pathogens, including anaerobes Anaerococcus and Finegoldia, was higher in swabs compared with tissue scrapings and significantly so in Staphylococcus and Pseudomonas genera. Multivariate analyses confirmed no significant differences between the bacterial community compositions of the paired samples. These results suggest that tissue scrapings and swabs can effectively capture the microbiome of chronic DFUs using culture and 16S rRNA gene sequencing. [ABSTRACT FROM AUTHOR]

The hypoxic tumor microenvironment (TME) significantly affects cancer treatment. Conventional chemotherapeutic agents cannot effectively target hypoxic tumor tissue, which decreases efficacy and results in severe toxic side effects. To alleviate this problem, a self‐driving biomotor is developed by functionalizing MCDP nanoparticles containing calcium peroxide and doxorubicin (DOX) loaded onto polydopamine‐coated metal–organic frameworks（MOF）, with the anaerobic Bifidobacterium infantis (Bif) for synergistic chemotherapy and chemodynamic therapy (CDT) against breast cancer. The materials of institute Lavoisier (MIL) frameworks + CaO2 + DOX + polydopamine (MCDP)@Bif biohybrid actively targets hypoxic regions of solid tumors via the inherent targeting ability of Bif. Once it has accumulated in the tumor tissue, MCDP generates hydroxyl radicals through the enhanced Fenton‐type reactions between Fe2+ and self‐generated hydrogen peroxide in the acidic TME. The disruption of Ca2+ homeostasis and resulting mitochondrial Ca2+ overload triggers apoptosis and enhances oxidative stress, promoting tumor cell death. The results found that the DOX concentration in MCDP@Bif‐treated tumors is 3.8 times higher than that in free‐DOX‐treated tumors, which significantly prolongs the median survival of the tumor‐bearing mice to 69 days and reduces the toxic side effects of DOX. Therefore, the novel bacteria‐driven drug delivery system is highly effective in achieving synergistic chemotherapy and CDT against solid tumors. [ABSTRACT FROM AUTHOR]

The etiology of irritable bowel syndrome (IBS) is unknown. Abnormal intestinal bacterial profiles and low bacterial diversity appear to play important roles in the pathophysiology of IBS. This narrative review was designed to present recent observations made relating to fecal microbiota transplantation (FMT), which implicate possible roles of 11 intestinal bacteria in the pathophysiology of IBS. The intestinal abundances of nine of these bacteria increased after FMT in patients with IBS, and these increases were inversely correlated with IBS symptoms and fatigue severity. These bacteria were Alistipes spp., Faecalibacterium prausnitzii, Eubacterium biforme, Holdemanella biformis, Prevotella spp., Bacteroides stercoris, Parabacteroides johnsonii, Bacteroides zoogleoformans, and Lactobacillus spp. The intestinal abundances of two bacteria were decreased in patients with IBS after FMT and were correlated with the severity of IBS symptoms and fatigue (Streptococcus thermophilus and Coprobacillus cateniformis). Ten of these bacteria are anaerobic and one (Streptococcus thermophilus) is facultative anaerobic. Several of these bacteria produce short‐chain fatty acids, especially butyrate, which is used as an energy source by large intestine epithelial cells. Moreover, it modulates the immune response and hypersensitivity of the large intestine and decreases intestinal cell permeability and intestinal motility. These bacteria could be used as probiotics to improve these conditions. Protein‐rich diets could increase the intestinal abundance of Alistipes, and plant‐rich diet could increase the intestinal abundance of Prevotella spp., and consequently improve IBS and fatigue. [ABSTRACT FROM AUTHOR]

Bacterial vaginosis (BV) is the most common cause of vaginal discharge and is often associated with other health consequences mainly in pregnant women. BV is described by an imbalance in the vaginal microbiota where strictly and facultative anaerobic bacteria outgrow the lactic acid‐ and hydrogen peroxide‐producing Lactobacillus species. The species involved in BV are capable to grow and form a polymicrobial biofilm in the vaginal epithelium. The treatment of BV is usually performed using broad‐spectrum antibiotics, including metronidazole and clindamycin. However, these conventional treatments are associated with high recurrence rates. The BV polymicrobial biofilm may have an important role on the treatment outcome and is accounted as one of the factors for treatment failure. Other possible reasons for treatment failure include the presence of species resistant to antibiotics or the chance of reinfection after treatment. Therefore, novel strategies to increase the rates of treatment have been studied namely the use of probiotics and prebiotics, acidifying agents, antiseptics, plant‐based products, vaginal microbiota transplantation, and phage endolysins. Although some of them are still in an initial phase of development with very preliminary results, they show great perspectives for application. In this review, we aimed to study the role of the polymicrobial nature of BV in treatment failure and explore a few alternatives for treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Jiuyao is a critical fermenting agent in traditional huangjiu brewing and it affects the quality of huangjiu. To assess and monitor the quality of jiuyao effectively we determined the differences between two common types of substandard jiuyao and normal jiuyao, with emphasis on the comparison of the main components, enzymatic activity, volatile substances, and microbial community structure. RESULTS: The water and starch content, acid protease activity, and esterification capability of type I substandard jiuyao were significantly lower than those of the normal jiuyao, and the protein contents, liquefaction capability, glycation capability, and neutral protease activity were substantially higher than those of the normal jiuyao. Type II substandard jiuyao had significantly lower indices than the normal group except for the starch and free amino acid content, which were significantly higher than those of the normal jiuyao. Significant differences were observed between substandard and normal jiuyao in the content of 21 volatile compounds. 2‐Pentylfuran could be used as a marker of substandard jiuyao. Type I substandard jiuyao contained a higher abundance of aerobic Pediococcus and Marivita in comparison with the normal jiuyao. Type II substandard jiuyao consisted of a greater abundance of anaerobic Mucor and Staphylococcus. CONCLUSION: The quality of jiuyao was significantly affected by the water content. Due to the different abundances of aerobic and anaerobic bacteria in jiuyao, oxygen may also be an important parameter affecting the quality of jiuyao. We believe that the present study offers a theoretical basis for the evaluation and control of the quality of jiuyao. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The combination of precise tumor depletion and immunotherapy presents great potential to exterminate cancer disease. Anaerobic bacteria can trigger innate and adaptive immune responses in tumors to facilitate the antitumor effects. However, bacteria injected intravenously induce systemic inflammation and are likely to be eliminated in the blood. Herein, live bacteria, Propionibacterium acnes (P. acnes), are integrated with ZnAl layered double hydroxides (LDHs) to construct an effective system enabling synergistic inhibition in both tumor growth and metastasis. In this system, P. acnes carries LDHs to reach and penetrate the hypoxic tumor tissue. The metabolism of colonized P. acnes and the pH‐responsive degradation of LDHs produce reactive nitrogen species and reactive oxygen species to trigger inevitable cell death. Furthermore, the decomposition of LDHs exposes P. acnes, and thus the immune response is activated to prohibit the reoccurrence of distant tumors. The biohybrid P. acnes@LDHs, developed in this study, possesses remarkable anticancer outcomes both in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Veillonella atypica is a nonmotile, nonsporulating anaerobic bacteria commonly found in various human biofilms. V. atypica FB0054 was isolated from the gastrointestinal tract of marathon runners, who have increased amounts of this species after athletic events. Interestingly, the consumption of this strain by rodents has been shown to increase their treadmill endurance, leading to the hypothesis that consumption of this species may improve athletic performance in humans as well. Further evaluation, in humans, of the usefulness of this strain should be preceded by safety studies. Therefore, the genotoxic and subchronic toxicological potential was evaluated as a contribution to this effort. Genotoxicity investigation was performed using the in vivo comet assay and in vivo mammalian micronucleus assay due to the anaerobic characteristic of the strain. A 90‐day, repeated‐dose oral toxicity study was performed in rats up to 2200 mg/kg bw/d to investigate general toxicity and identify any target organs. Mitsuoka buffer, a solution shown to preserve the viability of anaerobic bacteria, was used as the vehicle. All three studies revealed no toxicological effects from exposure to FB0054 was isolated from the gastrointestinal tract of marathon runners, who have increased amounts of this species after athletic events. Interestingly, the consumption of this strain by rodents has been shown to increase their treadmill endurance, leading to the hypothesis that consumption of this species may improve athletic performance in humans as well. Further evaluation, in humans, of the usefulness of this strain should be preceded by safety studies. Therefore, the genotoxic and subchronic toxicological potential was evaluated as a contribution to this effort. Genotoxicity investigation was performed using the in vivo comet assay and in vivo mammalian micronucleus assay due to the anaerobic characteristic of the strain. A 90‐day, repeated‐dose oral toxicity study was performed in rats up to 2200 mg/kg bw/d to investigate general toxicity and identify any target organs. Mitsuoka buffer, a solution shown to preserve the viability of anaerobic bacteria, was used as the vehicle. All three studies revealed no toxicological effects from exposure to FB0054 at the highest doses tested. Veillonella atypica is an anaerobic bacteria found in human biofilms. A specific strain, V. atypica FB0054, was isolated from the stool of marathon runners. Its investigation as a probiotic should be preceded by a safety evaluation. The in vivo comet assay and in vivo mammalian micronucleus assay revealed a lack of genotoxicity. A no‐observed‐adverse‐effect‐level of 2200 mg/kg bw/d in rats, the highest dose tested, was determined based on the results of a repeated‐dose subchronic oral toxicity study. [ABSTRACT FROM AUTHOR]

Background: Contemporary data reflecting local pathogens and their antibiograms is necessary to select empirical antimicrobial therapy for equine neonates. Hypothesis/Objectives: Describe bacterial isolates associated with equine neonatal infection and their antibiograms in the Midwestern United States. An increase in gram‐positive infection and antibiotic resistance compared to previous literature was expected. Animals: Data from 149 fluid samples from 133 foals <30 days of age submitted for bacterial culture between January 2007 and December 2018. Methods: A retrospective evaluation of equine neonatal fluid cultures was performed. Fluid submission type, bacterial culture and antibiogram, empirical antibiotic treatment, and foal outcome was included. Isolate susceptibility to individual antimicrobials and combination protocols relevant to equine practice were recorded. The effect of recorded variables on foal survival was evaluated using Fisher's exact or chi‐squared tests. Results: Ninety bacterial isolates (78 aerobes and 12 anaerobes) were identified and gram‐positive organisms predominated (n = 50/90, 56%). Greater than 70% of aerobic isolates were susceptible to ampicillin, ceftiofur, chloramphenicol, trimethoprim/sulfamethoxazole, and all penicillin/aminopenicillin and aminoglycoside combinations. Seventy‐seven (n = 81/105) percent of foals survived. Survival was associated with a negative fluid culture and was not associated with empirical antimicrobial choice. Conclusions and Clinical Importance: Gram positive and anaerobic isolates associated with equine neonatal fluid cultures exceed that of previous reports. Historical empirical antimicrobial choices for equine neonatal infection in the Midwestern United States are supported by local antibiogram results. [ABSTRACT FROM AUTHOR]

Semiochemical‐based management strategies are important for controlling bark beetles, such as invasive Red Turpentine Beetle (Denroctonus valens), the causal agent for mass mortality of pine trees (Pinus spp.) in China. It has been previously shown that the pheromone verbenone regulates the attack density of this beetle in a dose‐dependent manner and that the gut bacteria of D. valens are involved in verbenone production. However, molecular functional verification of the role of gut bacteria in the pheromone production of D. valens is still lacking. To better understand the molecular function of gut bacterial verbenone production, we chose a facultative anaerobic gut bacterium (Enterobacter xiangfangensis) of D. valens based on its strong ability to convert cis‐verbenol to verbenone, as shown in our previous study, and investigated its transcriptomics in the presence or absence of cis‐verbenol under anaerobic conditions (simulating the anoxic environment in the beetle's gut). Based on this transcriptome analysis, aldehyde dehydrogenase (ALDH1) was identified as a putative key gene responsible for verbenone production and was knocked‐down by homologous recombination to obtain a mutant E. xiangfangensis strain. Our results show that these mutants had significantly decreased the ability to convert the monoterpene precursor to verbenone compared with the wild‐type bacteria, indicating that ALDH1 is primarily responsible for verbenone conversion for this bacterium species. These findings provide further mechanistic evidence of bacterially mediated pheromone production by D. valens, add new perspective for functional studies of gut bacteria in general, and may aid the development of new gene silencing‐based pest management strategies. [ABSTRACT FROM AUTHOR]

In critically colonised wounds, many of the signs of infection are often absent, and delayed healing may be the only clinical sign. The prevention of critical colonisation is important, but its pathophysiology has not yet been elucidated. We have previously reported that dysbiotic microbiota dissimilar to the peri‐wound skin microbiota may develop in critically colonised wounds. To investigate the role of dysbiotic microbiota, this study aimed to develop a critically colonised wound model by transplantation of dysbiotic microbiota. To transplant microbiota, a bacterial solution (dysbiosis group) or with Luria‐Bertani medium (commensal group) was inoculated to full‐thickness wounds of rats. The bacterial solution was prepared by anaerobically culturing bacteria from donor rats on an artificial dermis in Luria‐Bertani medium for 72 hours. As a result, the degree of the change in the microbial similarity between pre‐ and post‐transplantation of microbiota was significantly higher in the dysbiosis group (P <.001). No signs of infection were observed in any rat in either group. The wound area in the dysbiosis group was significantly larger (P <.001), and there was a significant infiltration of neutrophils (P <.001). All rats of the dysbiosis group represented the clinical features of critically colonised wounds. Furthermore, there were significantly fewer regulatory T cells in the wounds of the dysbiosis group. This is the first study to develop a novel animal model that represents the clinical features of critically colonised wounds and will be useful in investigating the pathogenesis of critical colonisation via regulatory T cells. [ABSTRACT FROM AUTHOR]

Partial nitrification‐anammox (PN/A) is an energy‐efficient technology for nitrogen removal in landfill leachate treatment. Numerous studies have reported successful implementation of the PN/A process and its stable operation under laboratory conditions. One of the primary challenges in PN/A engineering applications is the mass of the seed sludge required for start‐up. This study examined the PN/A using a sequence batch reactor (SBR) inoculating a common mixture to treat landfill leachate. After 70 days of operation, the system successfully realized a one‐stage PN/A process and maintained a stable ammonium NH4+$$ \left({NH}_4^{+}\right) $$ removal efficiency of 97.65% ± 1%, where the effluent of NH4+$$ {NH}_4^{+} $$ and nitrate (NO3−$$ {NO}_3^{-} $$) were less than 4 ± 1.5 mg L−1 and 10 mg L−1. In addition, the relative abundances of Ca. Kuenenia and Ca. Brocadia, which are typical anaerobic ammonia‐oxidizing bacteria (AnAOB), increased from 0.08% to 3.99% (70 days) and 0.01% to 0.45%, respectively. The relative abundances of ammonia‐oxidizing bacteria (AOB) Nitrosomonas and Nitrosospira increased from 0.9% to 2.89% and 0.007% to 0.1% (70 days), respectively. Both AnAOB and AOB are important niches of the system. Practitioner Points: The research realized PN/A rapidly by inoculating common mixture sludge.The experiment successfully enriched AnAOB from 0.09% to 3.89% within 70 days.The article revealing the ecological roles of AOB and AnAOB in the landfill leachate treatment. [ABSTRACT FROM AUTHOR]

To determine if additional agar plates could allow earlier detection of anaerobes in spinal surgical site infections (SSIs), we performed a prospective study (November 2017‐January 2019) of patients with early spinal SSIs. In addition to routine 14‐day cultures, surgical samples were inoculated onto three additional plates (CDC anaerobe agar with 5% sheep blood [CDC], CDC anaerobe laked sheep blood agar with kanamycin/vancomycin [BBL], and Bacteroides bile esculin [BBE] agar with amikacin (BD, USA)) incubated under anaerobic conditions (72 h, 37°C). The primary endpoint was detection of anaerobes by these methods, as compared to routine culture. Anaerobes were identified in 7/61 patients (11%) using the routine procedure and in one extra case with additional plates (overall detection rate 8/61, 13%). Sensitivity was greater for the CDC plate than for the BBL and BBE plates. When routine culture was positive, the CDC plate was always positive, and in three cases showed at least one additional anaerobe. Using additional agar plates, anaerobes were identified in early spinal SSI in 13% of patients. Within 3 days, CDC agar plate enabled detection of anaerobes in one extra case and at least one additional anaerobe in three other cases, compared to routine 14‐day culture. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) lesions in humans have been proven to be severely hypoxic with hypoxia leading to latency and dormancy of disease. Dormant TB lesions become less susceptible to standard TB treatment regimens with varying responses to treatment but may have increased susceptibility to nitroimidazole drugs. This in turn implies that positron emission tomography / computed tomography (PET/CT) imaging with radiolabelled nitroimidazoles may identify patients who will benefit from treatment with antimicrobial agents that are active against anaerobic bacteria. This case series aims to highlight the hypoxic uptake and retention of a novel 68Ga‐labelled hypoxia‐seeking agent in TB lesions at different time points during anti‐TB therapy using PET/CT imaging. Patients with confirmed TB underwent whole‐body PET/CT after administration of a 68Ga‐nitroimidazole derivative at baseline and follow‐up. Images were analysed both qualitatively and semi‐quantitatively. Hypoxic uptake and change in uptake over time were analysed using lesion‐to‐muscle ratio (LMR) and lesion‐to‐blood ratio (LBR). 68Ga‐nitroimidazole avid lesions were demonstrated most frequently in the upper lobes of the lung. Low‐grade hypoxic uptake was visualised in areas of consolidation, cavitation, nodules and lymph nodes. From baseline to follow‐up imaging, the LMR increased with persistent hypoxic load despite morphologic improvement. This case series highlights the dynamic hypoxic microenvironment in TB lesions. From these initial data, it appears that 68Ga‐nitroimidazole is a promising candidate for monitoring hypoxic load in patients diagnosed with TB. Such imaging could identify patients who would benefit from individualised therapy targeting other mechanisms in the TB microenvironment with the intention to predict or improve treatment response. [ABSTRACT FROM AUTHOR]

The alicyclic compound cyclohexane carboxylate (CHC) is anaerobically degraded through a peripheral pathway that converges with the central benzoyl‐CoA degradation pathway of aromatic compounds in Rhodopseudomonas palustris (bad pathway) and some strictly anaerobic bacteria. Here we show that in denitrifying bacteria, e.g. Aromatoleum sp. CIB strain, CHC is degraded through a bad‐ali pathway similar to that reported in R. palustris but that does not share common intermediates with the benzoyl‐CoA degradation pathway (bzd pathway) of this bacterium. The bad‐ali genes are also involved in the aerobic degradation of CHC in strain CIB, and orthologous bad‐ali clusters have been identified in the genomes of a wide variety of bacteria. Expression of bad‐ali genes in strain CIB is under control of the BadR transcriptional repressor, which was shown to recognize CHC‐CoA, the first intermediate of the pathway, as effector, and whose operator region (CAAN4TTG) was conserved in bad‐ali clusters from Gram‐negative bacteria. The bad‐ali and bzd pathways generate pimelyl‐CoA and 3‐hydroxypimelyl‐CoA, respectively, that are metabolized through a common aab pathway whose genetic determinants form a supraoperonic clustering with the bad‐ali genes. A synthetic bad‐ali‐aab catabolic module was engineered and it was shown to confer CHC degradation abilities to different bacterial hosts. [ABSTRACT FROM AUTHOR]

This review is dedicated to the 50th anniversary of the discovery of hydrogenosomes by Miklós Müller and Donald Lindmark, which we will celebrate the following year. It was a long journey from the first observation of enigmatic rows of granules in trichomonads at the end of the 19th century to their first biochemical characterization in 1973. The key experiments by Müller and Lindmark revealed that the isolated granules contain hydrogen‐producing hydrogenase, similar to some anaerobic bacteria—a discovery that gave birth to the field of hydrogenosomes. It is also important to acknowledge the parallel work of the team of Apolena Čerkasovová, Jiří Čerkasov, and Jaroslav Kulda, who demonstrated that these granules, similar to mitochondria, produce ATP. However, the evolutionary origin of hydrogenosomes remained enigmatic until the turn of the millennium, when it was finally accepted that hydrogenosomes and mitochondria evolved from a common ancestor. After a historical introduction, the review provides an overview of hydrogenosome biogenesis, hydrogenosomal protein import, and the relationship between the peculiar structure of membrane translocases and its low inner membrane potential due to the lack of respiratory complexes. Next, it summarizes the current state of knowledge on energy metabolism, the oxygen defense system, and iron/sulfur cluster assembly. [ABSTRACT FROM AUTHOR]

A process for a more efficient and flexible use of the produced heat in biogas plants is tested under real operational conditions. The process uses a mesophilic digester and a thermophilic secondary digester, and the heat demand of the plant is covered by using the heat stored in the secondary digester. The efficient heat use is achieved by a controlled variation of temperature in combination with a suitable process monitoring, without affecting the biogas production or disturbing the biological process. The concept was previously tested in ideal laboratory conditions. Here, the validation tests, in preparation for a planned large‐scale trial, comprising one‐year semicontinuous fermentation tests in the laboratory (close to real operational conditions) are presented. These real conditions are characterized by a high organic load of the reactors as well as by a more manifold substrate mix. During the experimental phase, it is determined that the maximum temperature, at high variation rates between −4 and +2 K per day, reaches 54 °C, allowing a stable process. These experiments confirm that the adaptability to temperature changes depends on the boundary conditions of the fermentation and case‐specific experiments are required before significant changes are made to the temperature management of anaerobic digestion systems. [ABSTRACT FROM AUTHOR]

Sulfate is present in all freshwater and marine environments and is reduced to toxic and corrosive hydrogen sulfide by anaerobic bacteria. By measuring depth profiles of sulfate in sediments, it is possible to obtain estimates of sulfate reduction rates (SRRs). A whole‐cell microscale biosensor for sulfate was constructed by placing a mixture of sulfate‐reducing and aerobic bacteria in front of a hydrogen sulfide microsensor. The bacteria were supplied with electron donors from a reservoir behind the bacterial biomass. The aerobic bacteria ensured anaerobic conditions in deeper parts of the 150‐μm‐thick bacterial layer, so that the sulfate reducers could be active. A typical tip diameter of a sulfate biosensor is 50 μm. The calibration curve was close to linear in the 0–2 mM range, with a detection limit of about 10 μM. The 90% response time varied between 90 and 220 s, slowest response at low concentrations. Oxygen and ferrous iron at environmental concentrations gave no interference, but there was a 6% signal difference between stirred and stagnant liquid medium. The sensitivity of the biosensor could be modulated by applying a charge between sensor interior and an external electrode. The lifetime is usually a few weeks. The biosensor was used to measure sulfate profiles in a freshwater sediment. [ABSTRACT FROM AUTHOR]

Understanding antibiotic resistance mechanisms is central to the development of anti‐infective therapies and genomics‐based drug discovery. Yet, many knowledge gaps remain regarding the resistance strategies employed against novel types of antibiotics from less‐explored producers such as anaerobic bacteria, among them the Clostridia. Through the use of genome editing and functional assays, we found that CtaZ confers self‐resistance against the copper chelator and gyrase inhibitor closthioamide (CTA) in Ruminiclostridium cellulolyticum. Bioinformatics, biochemical analyses, and X‐ray crystallography revealed CtaZ as a founding member of a new group of GyrI‐like proteins. CtaZ is unique in binding a polythioamide scaffold in a ligand‐optimized hydrophobic pocket, thereby confining CTA. By genome mining using CtaZ as a handle, we discovered previously overlooked homologs encoded by diverse members of the phylum Firmicutes, including many pathogens. In addition to characterizing both a new role for a GyrI‐like domain in self‐resistance and unprecedented thioamide binding, this work aids in uncovering related drug‐resistance mechanisms. [ABSTRACT FROM AUTHOR]

Production of digestate pellets for fuel has been identified as a promising circular economy approach to provide renewable energy and additional income to farms, while at the same time presenting the potential to divert raw digestate from nutrient‐saturated land and reduce the risk to water quality. Although previous research has investigated the feasibility of pellet production, there has been little focus on the bio‐safety aspects of the system. Little is currently known about the persistence of bacteria present in the digestate and the potential impacts on human health for those handling this product. The aim of the present research was to determine the effect that each step in the pellet production process has on bacteria numbers: anaerobic digestion, mechanical separation, solid drying, and pelletisation. Enterobacteriaceae enumeration by colony count method was used to quantify bacteria, and the presence of Salmonella at each stage was determined. The Enterobacteriaceae count reduced with each stage, and the final pelletisation step reduced bacteria numbers to below detectable levels (<10 colony forming units/g). Salmonella was only detected in the starting slurry and absent from digestate onwards. Storage of the pellets under winter and simulated summer conditions showed no reactivation of Enterobacteriaceae over time. The pelletisation process produces a digestate product with Enterobacteriaceae counts below the maximum threshold (PAS110 specification) for transport off the source farm, but care must still be taken when handling digestate pellets as complete sterilisation has not been confirmed. [ABSTRACT FROM AUTHOR]

Benzoxazole scaffolds feature prominently in diverse synthetic and natural product‐derived pharmaceuticals. Our understanding of their bacterial biosynthesis is, however, limited to ortho‐substituted heterocycles from actinomycetes. We report an overlooked biosynthetic pathway in anaerobic bacteria (typified in Clostridium cavendishii) that expands the benzoxazole chemical space to meta‐substituted heterocycles and heralds a distribution beyond Actinobacteria. The first benzoxazoles from the anaerobic realm (closoxazole A and B) were elucidated by NMR and chemical synthesis. By genome editing in the native producer, heterologous expression in Escherichia coli, and systematic pathway dissection we show that closoxazole biosynthesis invokes an unprecedented precursor usage (3‐amino‐4‐hydroxybenzoate) and manner of assembly. Synthetic utility was demonstrated by the precursor‐directed biosynthesis of a tafamidis analogue. A bioinformatic survey reveals the pervasiveness of related gene clusters in diverse bacterial phyla. [ABSTRACT FROM AUTHOR]

Summary: To find an innovative use for orange peels discarded in the orange juice‐making process, a fermentative process was assessed using a Lactiplantibacillus plantarum strain. Blanched or rinsed peels were submerged in a 5% NaCl–3% inoculated sucrose brine for 10 days. Total soluble solids, pH, sugars and total aerobic and anaerobic counts were determined in the brines to characterise the process. The final products were characterised by instrumental texture, colour and volatile composition. The blanching pretreatment had a significant effect on the whole process and the final product characteristics. Anaerobic bacteria total counts were significantly higher in the blanched samples during the whole fermentation, and pH decreased significantly slower in these samples than in the rinsed ones. Rinsed samples were characterised by higher aerobic total counts, higher sucrose consumption and higher glucose, fructose and polyalcohols production. The texture was softer in the pretreated samples, probably due to the blanching process rather than the fermentation. The volatile composition was quite similar between samples, although it was different from one of the raw orange peels due to a significant decrease in various volatile compounds. [ABSTRACT FROM AUTHOR]

Due to the complexity, aggressiveness, and heterogeneity of malignant melanoma, it is difficult to eradicate the whole tumor through conventional treatment. Herein, a strategy of metabolic engineering labeled anaerobic oncolytic bacteria (Clostridium butyricum) is demonstrated to achieve the ablation of melanoma. In this system, the metabolic substrate of C. butyricum d-alanine (d-Ala) is first conjugated with a photosensitizer (TPApy) showing aggregation-induced emission (AIE). The yielded metabolic substrate of d-Ala-TPAPy can be metabolically incorporated into bacterial peptidoglycan to form engineered C. Butyricum. Once the engineered C. butyricum is injected into melanoma, the bacteria can only proliferate in an anaerobic zone, stimulate the tumor immune microenvironment, and ablate the tumor hypoxia region. Following that, the relatively rich oxygen content in the peripheral area can induce the death of C. butyricum. The photosensitizer (PS) on the bacteria can subsequently exert a photodynamic effect in the oxygen-rich region and further remove the melanoma residue under light irradiation. Prominent in vivo melanoma ablation results revealed that the engineering oncolytic bacteria can provide a promising regime for solid tumor eradication. [ABSTRACT FROM AUTHOR]

Anthropogenic activities and natural processes release dichloromethane (DCM, methylene chloride), a toxic chemical with substantial ozone‐depleting capacity. Specialized anaerobic bacteria metabolize DCM; however, the genetic basis for this process has remained elusive. Comparative genomics of the three known anaerobic DCM‐degrading bacterial species revealed a homologous gene cluster, designated the methylene chloride catabolism (mec) gene cassette, comprising 8–10 genes encoding proteins with 79.6%–99.7% amino acid identities. Functional annotation identified genes encoding a corrinoid‐dependent methyltransferase system, and shotgun proteomics applied to two DCM‐catabolizing cultures revealed high expression of proteins encoded on the mec gene cluster during anaerobic growth with DCM. In a DCM‐contaminated groundwater plume, the abundance of mec genes strongly correlated with DCM concentrations (R2 = 0.71–0.85) indicating their potential value as process‐specific bioremediation biomarkers. mec gene clusters were identified in metagenomes representing peat bogs, the deep subsurface, and marine ecosystems including oxygen minimum zones (OMZs), suggesting a capacity for DCM degradation in diverse habitats. The broad distribution of anaerobic DCM catabolic potential infers a role for DCM as an energy source in various environmental systems, and implies that the global DCM flux (i.e., the rate of formation minus the rate of consumption) might be greater than emission measurements suggest. [ABSTRACT FROM AUTHOR]

Multifunctional solar energy conversion offers a feasible strategy to solve energy, environmental and water crises. Herein, a series of platinum(II)‐tethered chalcogenoviologens (PtL+‐EV2+, E=S, Se, Te) is reported, which integrate the functions of photosensitizer, electron mediator and catalyst. PtL+‐EV2+ (particularly for PtL+‐SeV2+)‐based one‐component solar H2 production could be triggered not only by EDTA, but also by facultative anaerobic and aerobic bacteria relying on a simplified mechanism, along with efficient antibacterial activities. In addition, by using real pool water, PtL+‐SeV2+ achieved multiple functions, including H2 production, antibacterial action and acid removal, which supplied a new strategy to solve various problems in real life via a single system. [ABSTRACT FROM AUTHOR]

In November 2020 a mortality episode (30%) in juvenile Siberian and Russian sturgeons (Acipenser baerii, Brandt, and A. gueldenstaedtii, Brandt & Ratzeburg) and GUBA hybrid sturgeons (A. gueldenstaedtii × A. baerii) occurred in a hatchery in Northern Italy, associated with severe coelomic distension and abnormal reverse surface swimming. The fish were reared in concrete tanks supplied by well water, fed at 0.4% of body weight (b.w.) per day. Thirty sturgeon specimens were collected for necropsy, histological, bacteriological and virological examination. Macroscopic findings included diffuse and severe bloating of gastrointestinal tracts due to foamy contents with thinning and stretching of the gastrointestinal walls. Histological analysis revealed variable degrees of sloughing and necrosis of the intestinal epithelium, and the presence of bacterial aggregates. Anaerobic Gram‐positive bacteria were investigated, and Clostridium perfringens was isolated from the gut. Specific PCRs identified the toxinotype A and the β2 toxin gene. The daily feed administration was increased to 1.5% b.w. and after 5 days, the mortality ceased. A new animal cohort from the same groups was examined after 12 weeks, showing neither gut alterations nor isolation of C. perfringens. The imbalance of intestinal microbiota, presumably caused by underfeeding, favoured C. perfringens overgrowth and severe gas formation. The diet increase possibly restored the normal microbiota. [ABSTRACT FROM AUTHOR]

Desulfarculus baarsii and Desulfurivibrio alkaliphilus are strictly anaerobic bacteria existing in marine sediments. D. baarsii gains energy through reducing sulphate and D. alkaliphilus is able to reduce elemental sulphur, thiosulphate and polysulphide in seawater. Both organisms were previously identified as key organisms in sediment derived, bidirectional electroactive biofilms. Here, we investigated the electrochemical performance of these two bacteria in bio‐electrochemical systems and their possible involvement in anodic and cathodic reactions. The results show that D. baarsii was unable to donate or accept electrons to/from an electrode, while D. alkaliphilus was able to catalyse both anodic and cathodic reactions and interact with the electrode through direct or potentially indirect electron transfer. Raman spectra of D. alkaliphilus electrode biofilms showed a high similarity to Geobacter sulfurreducens biofilms, including the specific bands of cytochromes b and c, explaining the electroactivity of D. alkaliphilus in bioelectrochemical reactions. [ABSTRACT FROM AUTHOR]

Summary: Halorhodospira halophila, one of the most‐xerophilic halophiles, inhabits biophysically stressful and energetically expensive, salt‐saturated alkaline brines. Here, we report an additional stress factor that is biotic: a diminutive Candidate‐Phyla‐Radiation bacterium, that we named 'Ca. Absconditicoccus praedator' M39‐6, which predates H. halophila M39‐5, an obligately photosynthetic, anaerobic purple‐sulfur bacterium. We cultivated this association (isolated from the hypersaline alkaline Lake Hotontyn Nur, Mongolia) and characterized their biology. 'Ca. Absconditicoccus praedator' is the first stably cultivated species from the candidate class‐level lineage Gracilibacteria (order‐level lineage Absconditabacterales). Its closed‐and‐curated genome lacks genes for the glycolytic, pentose phosphate‐ and Entner–Doudoroff pathways which would generate energy/reducing equivalents and produce central carbon currencies. Therefore, 'Ca. Absconditicoccus praedator' is dependent on host‐derived building blocks for nucleic acid‐, protein‐, and peptidoglycan synthesis. It shares traits with (the uncultured) 'Ca. Vampirococcus lugosii', which is also of the Gracilibacteria lineage. These are obligate parasitic lifestyle, feeding on photosynthetic anoxygenic Gammaproteobacteria, and absorption of host cytoplasm. Commonalities in their genomic composition and structure suggest that the entire Absconditabacterales lineage consists of predatory species which act to cull the populations of their respective host bacteria. Cultivation of vampire : host associations can shed light on unresolved aspects of their metabolism and ecosystem dynamics at life‐limiting extremes. [ABSTRACT FROM AUTHOR]

The main etiological agent of periodontitis is the anaerobic bacterium Porphyromonas gingivalis. Virulence of this pathogen is controlled by various mechanisms and executed by major virulence factors including the gingipain proteases, peptidylarginine deiminase (PPAD), and RagB, an outer membrane macromolecular transport component. Although the structures and functions of these proteins are well characterized, little is known about their posttranslational maturation. Here, we determined the phosphoproteome of P. gingivalis in which phosphorylated tyrosine residues constitute over 80% of all phosphoresidues. Multiple phosphotyrosines were found in gingipains, PPAD, and RagB. Although mutation of phosphorylated residues in PPAD and RagB had no effect on secretion or activity, site‐directed mutagenesis showed that phosphorylation in hemagglutinin/adhesin domains of RgpA and Kgp, and in the catalytic domain of RgpB, had a strong influence on secretion, processing, and enzymatic activity. Moreover, preventing phosphorylation of one gingipain influenced the others, suggesting multiple phosphorylation‐dependent pathways of gingipain maturation in P. gingivalis. Various candidate kinases including Ptk1 BY kinase and ubiquitous bacterial kinase 1 (UbK1) may be involved, but their contribution to gingipain processing and activation remains to be confirmed. [ABSTRACT FROM AUTHOR]

One long‐standing question in microbiology is how microbes buffer perturbations in energy metabolism. In this study, we systematically analyzed the impact of different levels of ATP demand in Escherichia coli under various conditions (aerobic and anaerobic, with and without cell growth). One key finding is that, under all conditions tested, the glucose uptake increases with rising ATP demand, but only to a critical level beyond which it drops markedly, even below wild‐type levels. Focusing on anaerobic growth and using metabolomics and proteomics data in combination with a kinetic model, we show that this biphasic behavior is induced by the dual dependency of the phosphofructokinase on ATP (substrate) and ADP (allosteric activator). This mechanism buffers increased ATP demands by a higher glycolytic flux but, as shown herein, it collapses under very low ATP concentrations. Model analysis also revealed two major rate‐controlling steps in the glycolysis under high ATP demand, which could be confirmed experimentally. Our results provide new insights on fundamental mechanisms of bacterial energy metabolism and guide the rational engineering of highly productive cell factories. Synopsis: A systematic analysis of the impact of different levels of ATP demand on E. coli under various conditions reveals a biphasic response curve of the glucose uptake rate with respect to increasing ATP demand. E. coli strains with varying ATP demand were generated by overexpressing the F1‐ATPase encoding genes with different expression strengths.Under all conditions tested, E. coli can buffer increased ATP demand by elevating the glucose uptake rate, but only to a critical point, beyond which glucose consumption drops markedly.A kinetic model as well as metabolomic and proteomic data reveal that the dual dependency of the phosphofructokinase on ATP (substrate) and ADP (allosteric activator) causes this biphasic behavior and leads to a collapse under very high ATP demand.The results provide important insights into the fundamental mechanisms of bacterial energy metabolism and may guide the rational engineering of highly productive cell factories. [ABSTRACT FROM AUTHOR]

Oral dysfunction, including oral uncleanness and decline in tongue motor function, tongue pressure and swallowing function, precedes frailty. The tongue's dorsum is a reservoir of oral microbiota, desquamated epithelial mucosa and leukocytes due to the multi‐papillate anatomy, and leads to tongue coating. The tongue coating is frequently found in older adults because of hyposalivation, immunity's hypoactivity, diminished motor function and compromised tongue's pressure with age. Anaerobe‐driven volatile sulphur compounds in tongue coating are a major cause of intra‐oral malodor. Dysbiosis of the tongue‐coating microbiome rather than the amount of microorganisms is associated with a risk of aspiration pneumonia. Daily tongue cleaning with a brush or scraper is an easy way to control tongue coating deposits and quality. Using mouth wash or rinse‐containing germicides is also a way to control the microbiota of tongue coating. The tongue function is closely related to swallowing. Tongue and suprahyoid muscles are linked with respiratory muscles through the endothoracic fascia. The mechanical stimulation during the cleaning of the tongue may stimulate the respiratory muscles. An intervention trial revealed that tongue cleaning by mucosal brush improves tongue pressure, swallowing and respiratory function in old residents of nursing homes, suggesting a rehabilitative effect of tongue cleaning on the swallowing and respiratory functions, preventing aspiration pneumonia. This narrative review assesses the tongue‐cleaning benefits for respiratory and swallowing functions and the possibility of preventing aspiration pneumonia. [ABSTRACT FROM AUTHOR]

The understanding of how central metabolism and fermentation pathways regulate antimicrobial susceptibility in the anaerobic pathogen Bacteroides fragilis is still incomplete. Our study reveals that B. fragilis encodes two iron-dependent, redox-sensitive regulatory pirin protein genes, pir1 and pir2. The mRNA expression of these genes increases when exposed to oxygen and during growth in iron-limiting conditions. These proteins, Pir1 and Pir2, influence the production of short-chain fatty acids and modify the susceptibility to metronidazole and amixicile, a new inhibitor of pyruvate: ferredoxin oxidoreductase in anaerobes. We have demonstrated that Pir1 and Pir2 interact directly with this oxidoreductase, as confirmed by two-hybrid system assays. Furthermore, structural analysis using AlphaFold2 predicts that Pir1 and Pir2 interact stably with several central metabolism enzymes, including the 2-ketoglutarate:ferredoxin oxidoreductases Kor1AB and Kor2CDAEBG. We used a series of metabolic mutants and electron transport chain inhibitors to demonstrate the extensive impact of bacterial metabolism on metronidazole and amixicile susceptibility. We also show that amixicile is an effective antimicrobial against B. fragilis in an experimental model of intra-abdominal infection. Our investigation led to the discovery that the kor2AEBG genes are essential for growth and have dual functions, including the formation of 2-ketoglutarate via the reverse TCA cycle. However, the metabolic activity that bypasses the function of Kor2AEBG following the addition of phospholipids or fatty acids remains undefined. Overall, our study provides new insights into the central metabolism of B. fragilis and its regulation by pirin proteins, which could be exploited for the development of new narrow-spectrum antimicrobials in the future., (© 2024 The Author(s). MicrobiologyOpen published by John Wiley & Sons Ltd.)

Sulphate‐reducing bacteria (SRB) represent a key biological component of the global sulphur (S) cycle and are common in soils, where they reduce SO42− to H2S during the anaerobic degradation of soil organic matter. The factors that regulate their distribution in soil, however, remain poorly understood. We sought to determine the ecological patterns of SRB richness within a nationwide 16S metabarcoding dataset. Across 436 sites belonging to seven contrasting temperate land uses (e.g., arable, grasslands, woodlands, heathland and bog), SRB richness was relatively low across land uses but greatest in grasslands and lowest in woodlands and peat‐rich soils. There was a shift in dominant SRB taxa from Desulfosporosinus and Desulfobulbus in arable and grassland land uses to Desulfobacca in heathland and bog sites. In contrast, richness of other generalist anaerobic bacterial taxa found in our dataset (e.g., Clostridium, Geobacter and Pelobacter) followed a known trend of declining richness linked to land‐use productivity. Overall, the richness of SRBs and anaerobes had strong positive correlations with pH and sulphate concentration and strong negative relationships with elevation, soil organic matter, total carbon and carbon‐to‐nitrogen ratio. It is likely that these results reflect the driving influence of pH and competition for optimal electron acceptors with generalist anaerobic bacteria on SRB richness. Highlights: Sulphate‐reducing bacteria (SRB) are key but rare soil biota that may compete with other anaerobesAs UK sulphur deposition rates fall, local populations of SRB may also decline in soilsSulphate concentrations were higher in arable and wooded sites, not at higher elevation as expectedSRB richness was lower than generalist anaerobes, with peaks in grasslands and a drop in lowland woods. [ABSTRACT FROM AUTHOR]

Aim: Anammox bacteria are widely distributed in various environments, but the community composition and survival strategies of anammox bacteria in oligotrophic, deep‐sea water rich in dissolved oxygen (DO) remain unknown. We aimed to understand the distribution of anammox bacteria in the water columns of the South China Sea (SCS). Time period: Three cruises were in October 2014, October 2015 and September 2016, respectively. Location: Six water columns were obtained in the SCS, China (E 111–120°, N 16–22°). Methods: The diversity and community composition of anammox bacteria were investigated through a high‐throughput sequencing technique targeting the anammox 16S rRNA gene. Results: Unexpectedly, phylogenetic analysis showed that Ca. Brocadia (78.35%) was the dominant genus while Ca. Scalindua and unclassified species accounted for 12.62% and 9.03%, respectively. The highest diversity of anammox bacteria and concentrations of particulate organic matter (POM) were simultaneously observed in the 50–200 m layer, suggesting that particles may be a favourable niche for anammox bacteria. The wide distribution of anammox bacteria in the DO‐rich sea waters suggests two possible survival strategies: one strategy is attaching to particles and using anaerobic anammox metabolism to produce energy, and the other strategy is free‐living and using aerobic metabolism to produce energy. Main conclusions: A high diversity of anammox bacteria was found in the aerobic water columns, and Ca. Brocadia was the clearly dominant genus. Furthermore, anammox microbes could improve their viability by switching their metabolic pathways between anaerobic and aerobic conditions. Overall, our study has improved the understanding of the distribution and survival strategies of anammox communities in an aerobic marine environment and could provide new ideas for engineering applications in wastewater treatment with anammox technology. [ABSTRACT FROM AUTHOR]

In mammals, scent marking behavior is a pervasive form of chemical communication that regulates social interactions within and between groups. Glandular microbiota consist of bacterial communities capable of producing chemical cues used in olfactory communication. Despite countless studies on scent marking in primates, few have examined the microbiota associated with glandular secretions. Nancy Ma's owl monkeys (Aotus nancymaae) are nocturnal, socially monogamous primates that frequently scent mark using their subcaudal glands. Previous analyses revealed that unique chemical signatures of Aotus may convey information about sex and age. We used positive reinforcement to sample the subcaudal glands of 23 captive owl monkeys to describe their glandular microbiomes and examine how patterns in these bacterial communities vary with age, sex, rearing environment and/or social group (pair identity). We coupled these analyses with behavioral observations to examine patterns in their scent marking behavior. We isolated 31 bacterial species from Phyla Firmicutes, Proteobacteria, and Actinobacteria, consistent with the dermal and glandular microbiomes of other primates. Several bacterial taxa we identified produce volatile organic compounds, which may contribute to olfactory communication. These bacterial communities are best predicted by an interaction between sex, rearing environment and pair identity rather than any of these variables alone. Within mated pairs of A. nancymaae, males and females scent mark their nest boxes at similar frequencies. In some pairs, rates of scent marking by males and females fluctuated over time in a similar manner. Pairs that had been together longer tended to exhibit the greatest similarities in their rates of scent marking. Together, these findings suggest that scent marking behavior and close social interactions with pair mates in Aotus may influence bacterial transmission and their glandular microbiomes. Chemical communication, including coordinated scent marking, may play a role in strengthening pair bonds, signaling pair status and/or in mate guarding in this socially monogamous primate. RESEARCH HIGHLIGHTS: A diverse community of facultatively anaerobic bacteria inhabits the surface of the subcaudal gland on Aotus nancymaae, and many of these bacterial genera are known producers of volatile organic compounds.An interaction between sex, rearing environment and identity of social group better predict the structure of these bacterial communities than do any of these variables alone.Within mated pairs of A. nancymaae, males and females frequently scent marked a variety of surfaces in their enclosures, and scent marked their nest boxes at similar rates.In some pairs, rates of scent marking by males and females fluctuated in a similar manner across observation periods, and pairs that had been together longer tended to be more highly coordinated in their rates of scent marking. [ABSTRACT FROM AUTHOR]