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Tuberculosis remains a burden to this day, due to the rise of multi and extensively drug-resistant bacterial strains. The genome of Mycobacterium tuberculosis (Mtb) strain H37Rv underwent an annotation process that excluded small Open Reading Frames (smORFs), which encode a class of peptides and small proteins collectively known as microproteins. As a result, there is an overlooked part of its proteome that is a rich source of potentially essential, druggable molecular targets. Here, we employed our recently developed proteogenomics pipeline to identify novel microproteins encoded by non-canonical smORFs in the genome of Mtb using hundreds of mass spectrometry experiments in a large-scale approach. We found protein evidence for hundreds of unannotated microproteins and identified smORFs essential for bacterial survival and involved in bacterial growth and virulence. Moreover, many smORFs are co-expressed and share operons with a myriad of biologically relevant genes and play a role in antibiotic response. Together, our data presents a resource of unknown genes that play a role in the success of Mtb as a widespread pathogen. [ABSTRACT FROM AUTHOR]

A complex interplay of genetic and environmental factors influences bacterial growth. Understanding these interactions is crucial for insights into complex living systems. This study employs a data-driven approach to uncover the principles governing bacterial growth changes due to genetic and environmental variation. A pilot survey is conducted across 115 Escherichia coli strains and 135 synthetic media comprising 45 chemicals, generating 13,944 growth profiles. Machine learning analyzes this dataset to predict the chemicals' priorities for bacterial growth. The primary gene-chemical networks are structured hierarchically, with glucose playing a pivotal role. Offset in bacterial growth changes is frequently observed across 1,445,840 combinations of strains and media, with its magnitude correlating to individual alterations in strains or media. This counterbalance in the gene-chemical interplay is supposed to be a general feature beneficial for bacterial population growth. Genetic and environmental factors shaping bacterial growth are explored using profiles of E. coli. Machine learning revealed glucose-dependent gene-chemical hierarchies and negative epistasis, highlighting mechanisms that maintain growth homeostasis. [ABSTRACT FROM AUTHOR]

Mineral dissolution by bacteria is thought to depend on mineral properties, solution chemistry, and the carbon sources metabolized. To investigate whether mineral particle size could impact the effectiveness of weathering and the molecular mechanisms employed by bacteria, the strain Caballeronia mineralivorans PML1(12) was considered. Through microcosm and kinetic experiments, we quantified changes in biotite dissolution, bacterial growth, siderophore biosynthesis, and acidification. The use of different solution chemistries, carbon sources, and particle sizes (from <20 to 500 µm) allowed us to decipher the relative role of acidification- and chelation-driven mineral weathering by bacteria. Results revealed a faster dissolution for smaller particles (<100 µm) that strongly affected both solution chemistry and bacterial physiology, while larger particles (>100 µm) showed a slower and steady dissolution with minimal impact on bacterial processes. These findings underscore the influence and feedback effects of particle size on the dynamics of dissolution and the mechanisms employed by bacteria. [ABSTRACT FROM AUTHOR]

Polyproline sequences are deleterious to cells because they stall ribosomes. In bacteria, EF-P plays an important role in overcoming such polyproline sequence-induced ribosome stalling. Additionally, numerous bacteria possess an EF-P paralog called EfpL (also known as YeiP) of unknown function. Here, we functionally and structurally characterize EfpL from Escherichia coli and demonstrate its role in the translational stress response. Through ribosome profiling, we analyze the EfpL arrest motif spectrum and find additional sequences beyond the canonical polyproline motifs that both EF-P and EfpL can resolve. Notably, the two factors can also induce pauses. We further report that EfpL can sense the metabolic state of the cell via lysine acylation. Overall, our work characterizes the role of EfpL in ribosome rescue at proline-containing sequences, and provides evidence that co-occurrence of EF-P and EfpL is an evolutionary driver for higher bacterial growth rates. EF-P plays an important role in overcoming polyproline sequence-induced stalling in bacteria. Here, the authors show that its paralog, EfpL, can also resolve this type of stalling, and also sense cellular metabolic states via lysine acylation. [ABSTRACT FROM AUTHOR]

Exopolysaccharides (EPSs) synthesized by probiotic bacteria have the potential to be used as food additives with health benefits. The goal of the present work was to investigate the production of EPSs by probiotic strains isolated from traditional dairy products in Kerman (Iran) and to characterize the produced EPS. The EPS production pattern was assessed by the pattern of bacterial growth as well as the effects of temperature and acidity changes on EPS production. To characterize the EPSs, FTIR spectroscopy was performed. The antibiofilm activity of the extracted EPS was evaluated by determining the pre- and post-adhesion treatments of EPS. Finally, the highest EPS-producing isolate was identified by molecular methods. Of the 15 selected isolates, the highest amount of EPS (0.53 g/L) was observed for the D-8 isolate. This isolate was identified as Enterococcus hirae strain D-8 by morphological, biochemical, and 16S rDNA gene sequencing analysis. The highest EPS production was observed at 30°C and pH 7.5 and started at the late logarithmic phase. FTIR analysis of the EPSs revealed diverse functional groups, including (O–H), (C–H), (C=O), and aldehyde groups. The results of this research showed that bacterial EPSs not only inhibited biofilm formation but also disrupted the established biofilms of some strains. These results highlight the importance of investigating strains that are able to produce EPS to deal with antibiotic resistance and biofilm disruption. [ABSTRACT FROM AUTHOR]

Aquaculture faces significant challenges due to bacterial pathogens like Aeromonas hydrophila, which can severely impact production and fish health. Understanding the relationship between environmental factors, host susceptibility, and bacterial virulence is crucial for effectively managing and mitigating the risks associated with A. hydrophila in aquaculture systems. A. hydrophila, found ubiquitously in aquatic environments, possesses various virulence factors that enhance its pathogenicity. These factors are closely linked to environmental conditions, such as temperature and pH, which play pivotal roles in bacterial growth, survival, and pathogenic potential. Fluctuations in temperature and pH significantly influence A. hydrophila's metabolic activity and growth rate, thereby modulating its virulence and overall pathogenicity. Ammonia, a byproduct of aquatic organism metabolism and organic matter decomposition, can accumulate to toxic levels in aquaculture settings, compromising fish health and immune function. Elevated ammonia concentrations worsen A. hydrophila infections by compromising host immunity and creating favorable conditions for bacterial proliferation. Oxygen concentration, host signals, and diet formulation are significantly impacting the susceptibility of aquatic organisms to infection. These factors are the most crucial in shaping the ecology, physiology, and pathogenicity of A. hydrophila in aquaculture. There is limited information on how these environmental factors modulate the virulence genes of such important fish pathogens. The knowledge of A. hydrophila virulence and its interplay with environmental factors paves the way for developing strategies to prevent and control diseases in aquaculture. [ABSTRACT FROM AUTHOR]

Bacteria are key organisms in energy and nutrient cycles, and predicting the effects of temperature change on bacterial activity is important in assessing global change effects. A changing in situ temperature will affect the temperature adaptation of bacterial growth in lake water, both long term in response to global change, and short term in response to seasonal variations. The rate of adaptation may, however, depend on whether temperature is increasing or decreasing, since bacterial growth and turnover scale with temperature. Temperature adaptation was studied for winter (in situ temperature 2.5 °C) and summer communities (16.5 °C) from a temperate lake in Southern Sweden by exposing them to a temperature treatment gradient between 0 and 30 °C in ~ 5 °C increments. This resulted mainly in a temperature increase for the winter and a decrease for the summer community. Temperature adaptation of bacterial community growth was estimated as leucine incorporation using a temperature Sensitivity Index (SI, log growth at 35 °C/4 °C), where higher values indicate adaptation to higher temperatures. High treatment temperatures resulted in higher SI within days for the winter community, resulting in an expected level of community adaptation within 2 weeks. Adaptation for the summer community was also correlated to treatment temperature, but the rate of adaption was slower. Even after 5 weeks, the bacterial community had not fully adapted to the lowest temperature conditions. Thus, during periods of increasing temperature, the bacterial community will rapidly adapt to function optimally, while decreasing temperature may result in long periods of non-optimal functioning. [ABSTRACT FROM AUTHOR]

This investigation probes the role of the electron mediator, neutral red (NR), in the electrosynthesis process, specifically examining its effect on the production of succinic acid by Actinobacillus succinogenes. Our findings reveal that NR, when integrated into the cell membrane, is pivotal for sustaining MEC efficiency. Nevertheless, it is susceptible to both intrinsic and MECs-induced degradation. Notably, during the exponential growth phase of the bacteria, NR is readily incorporated into the cell membrane. However, the supplemental addition of NR fails to significantly enhance the MEC's capacity for succinic acid synthesis, no matter what stage of bacterial growth. And significant depletion of membrane-associated NR is not adequately compensated by the NR present in the fermentation liquid. The ORP feedback-regulated MECs adeptly conserve the NR on the cell membrane, which is essential for maintaining the efficiency of long-term electrosynthesis. The presence of NR on the cell membrane is essential for the functionality of MECs, yet its external replenishment hard. Implementing precise electro-potential regulation strategies can effectively diminish the degradation of NR, thus maintaining the system's efficiency. [ABSTRACT FROM AUTHOR]

The franciscana (Pontoporia blainvillei) is a small cetacean endemic to the southwestern Atlantic Ocean in a vulnerable conservation status. Their habitat is restricted to shallow waters and estuaries. In 2020, fresh female carcass of franciscana (juvenile/subadult) was found dead alone (individual stranding) on a public access beach in the Rio Negro Estuary in "Balneario El Cóndor", Argentinian Patagonia. Grossly, a widespread granulomatous lesion compatible with tuberculosis were observed. A sample of mesenteric lymph nodes with granulomatous lesions (~ 50 g) was collected for bacteriological culture and molecular identification. Bacterial growth was observed in Stonebrink media and Ziehl Neelsen staining revealed acid-fast bacilli. Identification of a Mycobacterium bovis strain with the SB0288 spoligotype was obtained. The spoligotype detected here has already been reported in cattle and humans. Presumably, fluids and feces of infected livestock and wild animals, or their carcasses, may contaminate the water. Thus, this report demonstrates the potential risk of zoonotic tuberculosis transmission through wastewater. Contaminated wastewater is eventually a threat to animal species living in the area, and potentially becomes a zoonotic risk. [ABSTRACT FROM AUTHOR]

Purpose: Although 5% povidone-iodine (PVP-I) is frequently used as an ocular antiseptic agent, there is a lack of consensus regarding the effects of PVP-I concentration, storage after opening, and compounded preparation on PVP-I antisepsis. We performed a series of in-vitro experiments to determine the impact of these factors on PVP-I's inhibition of common causes of post-procedural eye infection. Methods: Inhibition of microorganism growth was measured in-vitro as a function of active PVP-I exposure time. In control experiments, PVP-I was inactivated before microorganism exposure. Tested PVP-I solutions varied in concentration (0.6%, 5%, or 10%), length of storage after opening (0, 7, or 30 days), and preparation (commercial vs.compounded from stock PI solution). Tested pathogens included S. epidermidis, S. viridans, P. aeruginosa, methicillin-resistant S. aureus, methicillin-sensitive S. aureus, and C. albicans. Results: PVP-I solutions inhibited all bacterial growth by 3 min and fungal growth by 15 s. Compared to 5% PVP-I, the 0.6% PVP-I was less effective in inhibiting S. viridans growth (200 ± 0 colonies vs. 7 ± 8 at 30 s, P = 0.0004; 183 ± 21 vs. 0 ± 0 at 1 min, P = 0.018), but more effective in inhibiting P. aeruginosa (30 ± 20 vs. 200 ± 0 at 15 s, P = 0.019). Compared to commercial and newly-opened PVP-I solutions, compounded preparations and solutions stored for 7 or 30 days after bottle opening either preserved or improved antiseptic efficacy against tested microorganisms. Conclusions: Concentration of PVP-I solution affects antiseptic efficacy within 1 min of exposure, but all solutions performed equivalently at 3 min. In contrast to results of prior studies investigating dilute PVP-I, the 0.6% PVP-I did not demonstrate a uniformly equivalent or superior anti-septic effect. Compounded preparation and storage length after bottle opening did not decrease PVP-I antiseptic activity. [ABSTRACT FROM AUTHOR]

Environmental abuses and subsequent array of health hazards by petroleum products have emerged as a global concern that warrants proper remediation. Pyrene (PYR), a polycyclic aromatic hydrocarbon, is a xenobiotic by-product during crude petroleum processing. Biodegradation potential of two bacterial isolates (MK4 and MK9) of Brevibacterium sediminis from oil contaminated sites was explored. MK4 and MK9 could degrade PYR up to 23 and 59% (1000 mg.L− 1), respectively. A first-order formalism with the rate constant for MK4 and MK9 were found to be 0.022 ± 0.001 and 0.081 ± 0.005 day− 1, respectively with the corresponding half life period of 31.4 ± 1.4 and 8.6 ± 0.60 days respectively. Both the isolates produce biosurfactants as established by drop collapse assay, oil spreading and emulsification activity studies. Decrease in pH, change in absorbance (bacterial growth), and catechol formation support adaptation capability of the isolates to degrade PYR by using it as a source of carbon. PYR ring cleavage was induced by the ring hydroxylating dioxogenase enzyme present in the strains, as identified by PCR assay. In silico analyses of the PYR degrading enzyme revealed its higher binding affinity (-7.6 kcal.mol− 1) and stability (Eigen value:1.655763 × 10− 04) to PYR, as further supported by other thoeroretical studies. MK9 strain was more efficient than the MK4 strain in PYR degradation. Studies gain its prominence as it reports for the first time on the aptitude of B. sediminis as novel PYR-degrading agent that can efficiently be used in the bioremediation of petroleum product pollution with a greener approach. [ABSTRACT FROM AUTHOR]

Microbial growth is central to soil carbon cycling. However, how microbial communities grow under climate change is still largely unexplored. Here we use a unique field experiment simulating future climate conditions (increased atmospheric CO2 and temperature) and drought concomitantly and investigate impacts on soil microbial activity. We trace 2H or 18O applied via water-vapor exchange into membrane (and storage) fatty acids or DNA, respectively, to assess community- and group-level adjustments in soil microbial physiology (replication, storage product synthesis, and carbon use efficiency). We show that, while bacterial growth decreases by half during drought, fungal growth remains stable, demonstrating a remarkable resistance against soil moisture changes. In addition, fungal investment into storage triglycerides increases more than five-fold under drought. Community-level carbon use efficiency (the balance between anabolism and catabolism) is unaffected by drought but decreases in future climate conditions, favoring catabolism. Our results highlight that accounting for different microbial growth strategies can foster our understanding of soil microbial contributions to carbon cycling and feedback on the climate system. How climate change will impact microbial community growth is unclear. Here, the authors use a field experiment with varying global change factors, finding fungal growth more drought-resistant than microbial growth and overall changes in bacterial growth strategies. [ABSTRACT FROM AUTHOR]

Incorporating the inherent heterogeneity of living systems into models of active nematics is essential to provide a more realistic description of biological processes such as bacterial growth, cell dynamics and tissue development. Spontaneous flow of a confined active nematic is a fundamental feature of these systems, in which the role of heterogeneity has not yet been considered. We therefore determine the form of spontaneous flow transition for an active nematic film with heterogeneous activity, identifying a correspondence between the unstable director modes and solutions to Schrödinger's equation. We consider both activity gradients and steps between regions of distinct activity, finding that such variations can change the signature properties of the flow. The threshold activity required for the transition can be raised or lowered, the fluid flux can be reduced or reversed and interfaces in activity induce shear flows. In a biological context fluid flux influences the spread of nutrients while shear flows affect the behaviour of rheotactic microswimmers and can cause the deformation of biofilms. All the effects we identify are found to be strongly dependent on not simply the types of activity present in the film but also on how they are distributed. Incorporating the inherent heterogeneity of living systems into models of active nematics is essential to provide a realistic description of important biological processes. The authors determine the form of spontaneous flow transition for a heterogeneous active nematic film, finding a correspondence with Schrodinger's equation and changes to signature properties of the flow and transition threshold. [ABSTRACT FROM AUTHOR]

Melatonin (MLT) is a methoxyindole that has potent antioxidant actions, anti-inflammatory, and antiapoptotic capacity. However, its in vitro antibacterial capacity has been the least studied of its properties. Dimethylsulfoxide (DMSO) has been the most used solvent for these tests, but it shows an antimicrobial effect if it is not dissolved. Cyrene™ is a new solvent that has emerged as an alternative to DMSO. Therefore, this study aimed to determine the antimicrobial capacity of MLT by MIC assays, using Cyrene™ as a solvent. Likewise, the solubility of MLT in this solvent and whether it exerted any effect on bacterial growth at different percentages was also determined. Different dilutions of MLT in Cyrene™ with different concentrations, were prepared. No growth inhibition caused by MLT was observed. The growth inhibition observed was because of Cyrene™. The maximum amount of MLT that can be diluted in 100% Cyrene is 10 mg/mL, but this percentage of solvent shows a bactericidal effect. Therefore, it must be dissolved at 5% to avoid this effect, so only 4 mg/mL of MLT can be diluted in it. Therefore, if no other solvents are available, the in vitro antibacterial role of MLT cannot be adequately assessed. [ABSTRACT FROM AUTHOR]

This study conducted a detailed investigation on the influence of the culture medium type on the permeability reduction effect through microbial-induced calcium carbonate precipitation (MICP) technology in a single rough fracture. The differences between the Sporosarcina pasteurii cultured by two mediums were compared in terms of bacterial growth properties, permeability treatment effects, distribution characteristics of induced CaCO3, and microscopic crystal characteristics. The study revealed that the culture medium did indeed impact the permeability reduction effect when treated with MICP technology, primarily related to whether urea is added in the culture medium. Two distinct permeability reduction modes were proposed for the treatment process using Sporosarcina pasteurii cultured by different mediums through one-phase injection (mixing bacterial solution and cementing solution). The permeability decreased rapidly, and the distribution of induced CaCO3 was uneven after treatment with Sporosarcina pasteurii cultured in medium containing urea, while the permeability decreased relatively slowly and the induced CaCO3 distribution was relatively uniform when treated with Sporosarcina pasteurii cultured in medium without urea. Additionally, differences in crystal morphology were observed due to variations in seepage characteristics during the treatment process with the Sporosarcina pasteurii cultured by different mediums. Finally, some investigations were given to the treatment effect optimization for the treatment process of Sporosarcina pasteurii cultured in medium containing urea. This study gave an insight to the regulation mechanism of culture medium and treatment method for the process of permeability reduction by MICP technology in the rock fracture. [ABSTRACT FROM AUTHOR]

The eukaryotic Glucose Induced Degradation/C-Terminal to LisH (GID/CTLH) complex is a highly conserved E3 ubiquitin ligase involved in a broad range of biological processes. However, a role of this complex in host anti-microbial defenses has not been described. We exploited Mycobacterium tuberculosis (Mtb) induced cytotoxicity in macrophages in a FACS based CRISPR genetic screen to identify host determinants of intracellular Mtb growth restriction. Our screen identified 5 (GID8, YPEL5, WDR26, UBE2H, MAEA) of the 12 predicted members of the GID/CTLH complex as determinants of intracellular growth of both Mtb and Salmonella serovar Typhimurium. We show that the anti-microbial properties of the GID/CTLH complex knockout macrophages are mediated by enhanced GABAergic signaling, activated AMPK, increased autophagic flux and resistance to Mtb induced necrotic cell death. Meanwhile, Mtb isolated from GID/CTLH knockout macrophages are nutritionally starved and oxidatively stressed. Our study identifies the GID/CTLH complex activity as broadly suppressive of host anti-microbial responses against intracellular bacterial infections. Here, Simwela et al. perform a whole genome CRISPR/Cas9 screen on Mycobacterium tuberculosis infected primary macrophages and identify the GID/CTLH complex as a modulator of host cell physiology capable of promoting bacterial survival and growth. [ABSTRACT FROM AUTHOR]

Tuberculosis, caused by Mycobacterium tuberculosis, remains an enduring global health challenge due to the limited efficacy of existing treatments. Although much research has focused on immune failure, the role of host macrophage biology in controlling the disease remains underappreciated. Here we show, through multi-modal single-cell RNA sequencing in a murine model, that different alveolar macrophage subsets play distinct roles in either advancing or controlling the disease. Initially, alveolar macrophages that are negative for the CD38 marker are the main infected population. As the infection progresses, CD38+ monocyte-derived and tissue-resident alveolar macrophages emerge as significant controllers of bacterial growth. These macrophages display a unique chromatin organization pre-infection, indicative of epigenetic priming for pro-inflammatory responses. Moreover, intranasal BCG immunization increases the numbers of CD38+ macrophages, enhancing their capability to restrict Mycobacterium tuberculosis growth. Our findings highlight the dynamic roles of alveolar macrophages in tuberculosis and open pathways for improved vaccines and therapies. Mycobacterium tuberculosis infection remains a global health crisis. Here researchers characterise the alveolar macrophage subsets in a murine model of BCG vaccination in mice and link increases of CD38+ macrophages with restriction of bacterial growth. [ABSTRACT FROM AUTHOR]

Background: We examined whether the time to positivity (TTP) and growth and detection plot graph (GDPG) created by the automated blood culture system can be used to determine the bacterial load in bacteremic patients and its potential association correlation with disease severity. Methods: Known bacterial inocula were injected into the blood culture bottles. The GDPGs for the specific inocula were downloaded and plotted. A cohort of 30 consecutive clinical cultures positive for S. aureus and E. coli was identified. Bacterial load was determined by comparing the GDPG with the "standard" curves. Variables associated with disease severity were compared across 3 bacterial load categories (< 100, 100–1000, > 1000 CFU/mL). Results: S. aureus growth was sensitive to the blood volume obtained whereas E. coli growth was less so. A 12-hour delay in sample transfer to the microbiology laboratory resulted in a decrease in TTP by 2–3 h. Mean TTP was 15 and 10 h for S. aureus and E. coli, respectively, which correlates with > 1000 CFU/mL and 500–1000 CFU/ml. For S. aureus, patients with a bacterial load > 100 CFU/mL had a higher mortality rate, (OR for death = 9.7, 95% CI 1.6–59, p = 0.01). Bacterial load > 1000 CFU/mL had an odds ratio of 6.4 (95% CI1.2-35, p = 0.03) to predict an endovascular source. For E. coli bacteremia, we did not find any correlations with disease severity. Conclusion: GDPG retrieved from the automated blood culture system can be used to estimate bacterial load. S.aureus bacterial load, but not E.coli, was associated with clinical outcome. [ABSTRACT FROM AUTHOR]

Monitoring chicken meat is a crucial process for food safety and consumer health, as it helps prevent the growth of harmful bacteria, minimizing the risk of foodborne illnesses. Currently, electronic nose (E-nose) technology plays a significant role in food quality assessment as it can detect changes in volatile compounds associated with food freshness. In this study, a self-designed, cost-efficient E-nose system was introduced to evaluate the freshness and bacterial growth of vacuum-packaged chicken meat stored at room temperature and refrigerator at 4 °C. Polynomial feature extraction with varying degrees was employed to extract important information from the sensor responses. Principal component analysis (PCA) and linear discriminant analysis (LDA) were implemented for data dimensionality reduction and classification. A support vector regression (SVR) model was built and employed to evaluate the bacteria population based on response patterns from the E-nose device. The LDA results clearly showed the classification of chicken meat freshness corresponding to different storage days and temperatures. The E-nose device with the SVR model combined with extracted parameters using a 2-degree polynomial provided good prediction results for the bacteria population with high scores of 0.99 and 0.99, scores of 0.97 and 0.93, and minimum scores of 0.08 and 0.11 log , and scores of 0.24 and 0.30 log , at room and refrigerated temperatures, respectively. The results indicate that the developed E-nose system could be used as a fast, portable, low-cost, and non-destructive measurement tool in evaluating the bacterial growth of chicken meat with high relative accuracy. Highlights: Electronic nose (E-nose) was used to predict the bacteria population of chicken meat. Enhanced performance was achieved using a second-degree polynomial feature method. values > 0.93 and were obtained using SVR model. The method is nondestructive and could be applied in a real-world environment. [ABSTRACT FROM AUTHOR]

Significant emphasis has been directed towards the advancement of antimicrobial agents with the objective of mitigating and managing the transmission of infectious diseases. Silver nanoparticle-decorated carbon nanotube (Ag@CNT)-based metal organic frameworks (MOFs) represent a promising nanomaterial endowed with significant antibacterial efficacy and hold potential for diverse medical applications, especially mitigating the proliferation of infectious microbes. In this study, silver nanoparticles (Ag NPs) were conjugated onto the exterior side wall of functionalized carbon nanotubes (F-CNT) employing the one-step ultrasonication technique at 37°C for a duration of 6 h. Colloidal AgNPs were loaded onto the side wall of the F-CNT for the fabrication of Ag@CNT MOF. Fabricated Ag@CNT MOF nanocomposites were subjected to comprehensive characterization employing cutting-edge analytical methods, including UV-Vis, SEM, TEM, FTIR, Raman spectroscopy, and XRD. The antimicrobial efficacy of Ag@CNT MOF nanocomposites was assessed against Staphylococcus aureus by using well diffusion and microbroth dilution methods. The synthesized Ag@CNT MOF demonstrated enhanced antimicrobial activity against S. aureus bacteria. In our in vitro investigations, we observed significant inhibition zones with diameters of 43 mm ± 0.9 mm and 50 mm ± 0.4 mm at concentrations of 0.5 mg/mL and 1.0 mg/mL using the well diffusion technique. Additionally, there was a 78% decrease in bacterial growth of S. aureus when exposed to 128 µg/mL concentration of Ag@CNT. [ABSTRACT FROM AUTHOR]

Traditionally, bacteriostatic antibiotics are agents able to arrest bacterial growth. Despite being traditionally viewed as unable to kill bacterial cells, when they are used clinically the outcome of these drugs is frequently as effective as when a bactericidal drug is used. We explore the dynamics of Escherichia coli after exposure to two ribosome-targeting bacteriostatic antibiotics, chloramphenicol and azithromycin, for thirty days. The results of our experiments provide evidence that bacteria exposed to these drugs replicate, evolve, and generate a sub-population of small colony variants (SCVs) which are resistant to multiple drugs. These SCVs contribute to the evolution of heteroresistance and rapidly revert to a susceptible state once the antibiotic is removed. Stated another way, exposure to bacteriostatic drugs selects for the evolution of heteroresistance in populations previously lacking this trait. More generally, our results question the definition of bacteriostasis as populations exposed to bacteriostatic drugs are replicating despite the lack of net growth. Traditionally, bacteriostatic antibiotics were thought to simply arrest bacterial growth. In this work, the authors explore the dynamics of Escherichia coli when exposed to bacteriostatic antibiotics, finding that long-term exposure to bacteriostatic antibiotics favors the evolution of heteroresistant small colony variants. [ABSTRACT FROM AUTHOR]

We evaluated the activity of piperacillin in relation to increasing tazobactam concentration against ESBL-producing Enterobacterales collected from patients with bacteraemia. Increasing tazobactam concentration (4, 12 or 24 mg/L) exerted a reduction of piperacillin MICs under the clinical breakpoint in a concentration-dependent manner (0%, 60% and 90% of clinical isolates). Also, activity of piperacillin/tazobactam based at higher achievable serum concentrations (123/14 mg/L) is needed to reduce the bacterial growth in 92% of ESBL-producers. Changes in the piperacillin MIC in relation to increasing tazobactam suggest that realtime TDM could be used for driven antimicrobial therapy with piperacillin/tazobactam in BSI due to ESBL strains. [ABSTRACT FROM AUTHOR]

The study aimed to develop plant-based model snacks that are high in fibre, contain probiotic bacteria and are convenient for long-term storage. The research focused on selecting a suitable form of probiotic bacteria (active biomass, microencapsulated, freeze-dried), inoculation method (in the base mass or in the filling of a snack) and appropriate storage conditions (4°Cor 20 °C). The potential synbiotic properties were evaluated. The microencapsulated bacteria had the highest survival rate at 4 °C, while the freeze-dried bacteria showed better survival rates at 20 °C. Probiotics had a higher survival rate when enclosed inside snacks with a low water activity (aw = 0.27) peanut butter filling than in snacks without filling (aw = 0.53). Enclosing the probiotics in a low aw filling ensures their survival at ambient temperature for 5 months at a count higher than 6 log CFU/g. The snacks exhibited high antioxidant capacity (average 300 mg ascorbic acid equivalent/100 g), polyphenol content (average 357 mg gallic acid equivalent/100 g) and high fibre content (average 10.2 g/100 g). The sensory analysis showed a high overall quality of the snacks (average 7.1/10 of the conventional units). Furthermore, after six months of storage, significant changes were observed in the antioxidant properties, polyphenol content and texture of the snacks, while their sensory quality remained unchanged. Moreover, a potential synbiotic effect was observed. The method used to assess bacterial growth indicated significantly higher values in the model snacks compared to a control sample. Therefore, this study has effectively addressed the gap in knowledge regarding the survival of probiotics in snacks of this nature. [ABSTRACT FROM AUTHOR]

In this study, growth and enzyme production of Bacillus megaterium RB-05 was achieved at varying parameters such as temperature, incubation time, pH, carbon source and nitrogen source. Naturally occurring sand with 97% quartz was utilized as the matrix for bacterial growth and CaCO3 precipitation. The estimation of CaCO3 precipitation was done through gravimetric analysis and CaCO3 deposition was detected through EDX and SEM analysis. Furthermore, sand stabilization was determined through Drained triaxial tests. The results obtained showed maximum bacterial growth and urease activity at pH 7, 350C temperature and 48 h incubation time. Bacteria showed maximum growth with glucose as carbon source however, significant urease activity was observed with both glucose and maltose. Optimum bacterial growth was observed with ammonium chloride as the nitrogen source however, maximum urease activity was observed with ammonium sulphate. CaCO3 precipitation of treated sand showed a linear relation between CaCO3 precipitation with urease production. The EDX and SEM analysis showed CaCO3 deposition between sand particles and on the surface. Furthermore, the stress response of sand showed enhanced sand strength at maximum CaCO3 precipitation. The obtained results show the link between urease production, CaCO3 precipitation, and sand stabilization by MICP. High urease activity influences CaCO3 precipitation in the soil followed by enhanced soil strength. However, the positive results were obtained in reactor environment, further studies are required to make the technique applicable. [ABSTRACT FROM AUTHOR]

Mold growth on body donations remains an underreported yet serious issue in anatomical teaching. Bacterial and fungal growth pose health risks to lecturers and students, alongside with ethical and aesthetic concerns. However, limited information exists on the presence of bacteria and fungi on body donations and their underlying causes. To investigate the potential impact of airborne germs on body donation contamination, we conducted indoor air measurements before, during, and after our anatomical dissection course, with outdoor measurements serving as a control. Tissue samples from the dissected body donations were collected to assess the germ load, with qualitative and quantitative microbiological analyses. Air samples from the dissection hall contained no fungi, but various fungal species were identified in the adjacent stairways and outdoors which implies that fungal occurrence in the dissection hall air was independent of lecturers' and students' presence. Moreover, our results indicate that adequate ventilation filters can effectively reduce indoor fungal germs during courses, while the bacterial load in room air appears to increase, likely due to the presence of lecturers and students. Additionally, the tissue samples revealed no bacterial or fungal germs which implies that our ethanol-formalin-based embalming solution demonstrates an effective long-term antimicrobial preservation of corpses. [ABSTRACT FROM AUTHOR]

Siderophores are specialized molecules produced by bacteria and fungi to scavenge iron, a crucial nutrient for growth and metabolism. Catecholate-type siderophores are mainly produced by bacteria, while hydroxamates are mostly from fungi. This study investigates the capacity of nine hydroxamate-type siderophores from fungi and Streptomyces to facilitate iron acquisition by the human pathogen Pseudomonas aeruginosa. Growth assays under iron limitation and 55Fe incorporation tests showed that all nine siderophores promoted bacterial growth and iron transport. The study also aimed to identify the TonB-dependent transporters (TBDTs) involved in iron import by these siderophores. Using mutant strains lacking specific TBDT genes, it was found that iron is imported into P. aeruginosa cells by FpvB for coprogen, triacetylfusarinine, fusigen, ferrirhodin, and ferrirubin. Iron complexed by desferioxamine G is transported by FpvB and FoxA, ferricrocin-Fe and ferrichrycin-Fe by FpvB and FiuA, and rhodotoluric acid-Fe by FpvB, FiuA, and another unidentified TBDT. These findings highlight the effectiveness of hydroxamate-type siderophores in iron transport into P. aeruginosa and provide insights into the complex molecular mechanisms involved, which are important for understanding microbial interactions and ecological balance. [ABSTRACT FROM AUTHOR]

Purpose: About 50% of individuals with long-term indwelling catheters are affected by catheter encrustations and bladder stone formation. Therefore, prophylaxis of catheter encrustations is important. Currently, however, neither an established prophylaxis nor a standardized in-vitro model to test different measures exist. We have therefore developed and qualitatively evaluated an in-vitro model of catheter encrustation. Methods: Size 14 French suprapubic catheters were incubated under sterile conditions at 37 degrees Celsius in five different media: (1) sterile artificial urine (n = 16), (2) artificial urine with E. coli (n = 8), (3) with Pseudomonas aeruginosa (n = 8), (4) with Proteus mirabilis (n = 8), and (5) with a mix of these three strains (n = 8). Catheter balloons were inflated either a glycerine or a bactericidal solution. After 6 weeks, the catheters were removed from the solution, dried, and weighed, and a photometric determination of the retrieved encrustations was performed. Results: Most frequently and pronounced encrustations were detected in the Pseudomonas group. The median weight of these encrustations (50% struvite and brushite) was 84.4 mg (47.7 mg / 127.3 mg). Even on catheters stored in sterile urine, encrustations (69.2% struvite) were found. Bacterial growth was not affected by the medium used for catheter blockage. Conclusion: Although in-vitro models appear to be limited because they lack "the human factor", they are valuable for systematically assessing physico-chemical factors affecting encrustations. Therefore, our model, being reliable and cost-effective, may foster further research despite its limitations. [ABSTRACT FROM AUTHOR]

Periodontitis is initiated by dysbiosis of the oral microbiome. Pathogenic bacteria elicit ineffective immune responses, which damage surrounding tissues and lead to chronic inflammation. Although current treatments typically aim for microbial eradication, they fail to address the significance of immune cell reactions in disease progression. Here, we searched for small molecules as drug candidates and identified a bifunctional antibiotic, azithromycin (AZM), that not only inhibits bacterial growth but also modulates immune cells to suppress inflammation. We further engineered a dissolvable microneedle patch loaded with biodegradable microparticles for local and painless delivery of AZM to the gingival tissues. Inflammatory cytokines were decreased while anti-inflammatory cytokines and M2 macrophage were increased with AZM treatments in vitro. In vivo delivery of the AZM-loaded microneedle patch demonstrated the same effects on cytokine secretion and the promotion of tissue healing and bone regeneration. In addition, microparticles containing anti-inflammatory interleukin-4 alone or in combination with separately-formulated AZM microparticles, had similar or slightly enhanced therapeutic outcomes respectively. The bimodal action of AZM obviates the necessity for separate antibacterial and immunomodulatory agents, providing a practical and streamlined approach for clinical treatment. Our findings also demonstrate the therapeutic efficacy of microparticles delivery into the soft tissues by a minimally invasive and fast-degrading microneedle patch and offer a novel therapeutic approach for the treatment of periodontitis and other diseases through immunomodulation. Highlights: • Dual actions of a single compound with both antibiotic and immunomodulatory effects can suppress inflammation and promote tissue regeneration. • Fast-dissolving microneedle patch enables minimally invasive and local delivery of biodegradable microparticles as distributive depots for sustained release of therapeutics in diseased tissues. [ABSTRACT FROM AUTHOR]

Probiotic production in commercial culture media is expensive, so, it is necessary to design culture media based on "low-cost" components like agro-industrial by-products. Therefore, this study aimed to design an agro-industrial by-product-based culture media using whey, sugarcane molasses, and palm kernel cake as components to produce Lactococcus lactis A12, Priestia megaterium M4, and Priestia sp. M10 isolated from Nile tilapia (Oreochromis niloticus) associated gut microbiota. Higher bacterial concentrations were achieved at high whey concentrations and low concentrations of sugarcane molasses and palm kernel cake (PKC) using agitation. The optimal conditions were whey, 3.84% w/v; sugarcane molasses, 7.39% w/v; PKC, 0.77% w/v; and agitation speed, 75 RPM. Bacterial growth under optimal conditions was compared to that in commercial Brain–Heart Infusion (BHI) broth. L. lactis A12 showed similar growth in the optimal media and BHI. The estimated cost of the culture media based on component prices was USD $ 3.01/L, which is 86.93% lower than BHI broth (USD $ 23.04/L). It was possible to design a "low-cost agro-industrial by-product-based culture media to produce L. lactis A12 and the two Priestia species under monoculture conditions. [ABSTRACT FROM AUTHOR]

Hospital-acquired infections are a marked burden on the healthcare system and the leading cause of death in hospitals. Medical devices and implants contribute significantly to the infection because it has direct contact with the patient body cavity. To solve this issue surface of the devices needs to be modified for efficient functioning. To achieve different surface properties advanced surface modification strategies like plasma-assisted surface modification, plasmonic lithography, nanopatterning by laser beam or electron beam, and chemical etching oxidation can be used. Nanostructure inhibits bacterial growth without causing toxicity or the least toxicity to the surrounding tissue in the human body. The current review summarizes the numerous surface modification strategies adopted for developing novel nanostructured surfaces with more emphasis on titanium-based nanostructure in medical devices along with a brief review of the bactericidal mechanism. This review also sheds some light on the biomedical importance of polymeric and Inorganic nanocomposite materials with their biocompatibility and toxicity profile. Highlights: Surface modulation of medical devices reduces the chance of infection by inhibiting the growth of harmful microbes. The nanostructured surface of titanium discourages bacterial growth. Inorganic and polymeric nanocomposite structures can be used in the fabrication of medical device surface. Biocompatibility of the nanostructured surface. [ABSTRACT FROM AUTHOR]

Resistance to antibiotics is a critical growing public health problem that desires urgent action to combat. To avoid the stress on bacterial growth that evokes the resistance development, anti-virulence agents can be an attractive strategy as they do not target bacterial growth. Quorum sensing (QS) systems play main roles in controlling the production of diverse virulence factors and biofilm formation in bacteria. Thus, interfering with QS systems could result in mitigation of the bacterial virulence. Cilostazol is an antiplatelet and a vasodilator FDA approved drug. This study aimed to evaluate the anti-virulence activities of cilostazol in the light of its possible interference with QS systems in Pseudomonas aeruginosa. Additionally, the study examines cilostazol's impact on the bacterium's ability to induce infection in vivo, using sub-inhibitory concentrations to minimize the risk of resistance development. In this context, the biofilm formation, the production of virulence factors and influence on the in vivo ability to induce infection were assessed in the presence of cilostazol at sub-inhibitory concentration. Furthermore, the outcome of combination with antibiotics was evaluated. Cilostazol interfered with biofilm formation in P. aeruginosa. Moreover, swarming motility, biofilm formation and production of virulence factors were significantly diminished. Histopathological investigation revealed that liver, spleen and kidney tissues damage was abolished in mice injected with cilostazol-treated bacteria. Cilostazol exhibited a synergistic outcome when used in combination with antibiotics. At the molecular level, cilostazol downregulated the QS genes and showed considerable affinity to QS receptors. In conclusion, Cilostazol could be used as adjunct therapy with antibiotics for treating Pseudomonal infections. This research highlights cilostazol's potential to combat bacterial infections by targeting virulence mechanisms, reducing the risk of antibiotic resistance, and enhancing treatment efficacy against P. aeruginosa. These findings open avenues for repurposing existing drugs, offering new, safer, and more effective infection control strategies. [ABSTRACT FROM AUTHOR]

This manuscript presents a new report on the in vitro antimicrobial photo-inactivation of foodborne microorganisms (Salmonella spp. and Listeria monocytogenes) using tetra-cationic porphyrins. Isomeric tetra-cationic porphyrins (3MeTPyP, 4MeTPyP, 3PtTPyP, and 4PtTPyP) were tested, and antimicrobial activity assays were performed at specific photosensitizer concentrations under dark and white-light LED irradiation conditions. Among the tested bacterial strains, 4MeTPyP exhibited the highest efficiency, inhibiting bacterial growth within just 60 min at low concentrations (17.5 μM). The minimal inhibitory concentration of 4MeTPyP increased when reactive oxygen species scavengers were present, indicating the significant involvement of singlet oxygen species in the photooxidation mechanism. Furthermore, the checkerboard assay testing the association of 4MeTPyP showed an indifferent effect. Atomic force microscopy analyses and dynamic simulations were conducted to enhance our understanding of the interaction between this porphyrin and the strain's membrane. [ABSTRACT FROM AUTHOR]

Sulfonated β-cyclodextrin (CD1) combined with nanocurcumin or nanoclay was used to prepare multifunctional polyurethane (PU) coatings having antimicrobial capabilities. The combination resulted in formation of an inclusion complex which is confirmed by Raman studies and Job's plot analysis. The co-precipitation method is employed to achieve two inclusion complexes by combining CD1 with Cloisite 30B (C30B) and nanocurcumin (NC) separately. The resultant nanocomposite coating samples exhibit < 100 °C deviation at 50% weight loss from PU in heat resistance, as well as a 78% enhancement in toughness and 2.3–3 cm of zone of inhibition which is comparable to amoxicillin in its performance in resistance to bacterial growth. The advantage of absorbing such inclusion complexes into polymer coatings is the creation of multifunctionalities such as hydrophobicity, flame retardance, thermally stable and low intumescent coatings. [ABSTRACT FROM AUTHOR]

Silkworm pupae as widely consumed insect products are good biosources of protein and micronutrients. Silkworm rearing throughout the year can be achieved by feeding them an artificial diet instead of native plants, facilitating extensive pupa production. However, artificial diets are prone to spoilage caused by bacterial contamination. Here, we evaluated the antiseptic effect of ethylparaben (EP, chemical preservative) and medium-chain fatty acids (MCFA, natural preservative) in a silkworm artificial diet. Results showed that both preservatives effectively inhibited pathogenic bacterial growth. Furthermore, the addition of EP or MCFA did not negatively impact the production capacity of silkworms and the homeostasis of gut microbiota. However, the expression of genes involved in detoxification such as Ugt2, and immune response such as Cecropin B, were upregulated after EP consumption. Therefore, natural preservative MCFA emerges as a suitable option from a safety perspective. These findings highlight future directions for improving insect artificial diet formulation. [ABSTRACT FROM AUTHOR]

Background: Contamination in the contact lens training area could be due to bacteria, which can lead to the major consequence of ocular infections. We aimed to investigate the contamination caused by bacteria in the contact lens training area in private optical clinics of the Udupi district, India. Methods: A cross-sectional study evaluated the swabs from the contact lens container, contact lens solution tip, washing area and lens fitting area for bacterial contamination. Twenty swabs collected from different areas of five optical clinics were inoculated in Brain heart infusion broth (BHIB). The broth was streaked in MacConkey and Blood agar and incubated at standard conditions for the growth of bacteria. All isolates were identified using conventional culture methods, and Gram staining was performed. Results: Twenty samples (contact lens case, n = 5; contact lens solution tip, n = 5; washing area, n = 5; cleaning towel, n = 5) from private optical clinics were recruited for the study. Bacterial growth was indicated in which lactose fermentation was seen at (15%), non-lactose fermentation at (35%), and no bacterial growth at (50%) in MacConkey agar. Partial or alpha-hemolytic (α hemolysis) was seen in (5%), complete or beta-hemolytic (β hemolysis) was seen in (40%), no hemolysis or gamma hemolysis (ϫ haemolysis), was seen in (30%), no growth was seen in (25%) on blood agar. Gram-positive cocci (45%), Gram-negative bacilli (20%), and no increase in (35%) were observed in MacConkey agar and Blood agar. Bacterial species were not identified in this study. Conclusion: Contamination was found in lenses, solution tips, washing areas, and cleaning towels which might lead to ocular infections. Perception should be given to those responsible for fitting lenses. [ABSTRACT FROM AUTHOR]

The abiotic transformations of quinolones and tetracyclines facilitated by redox-active minerals has been studied extensively, however limited information is available regarding the antimicrobial activity and toxicity of their resultant transformation products. In this study, we first investigated the mechanisms underlying the transformation of two commonly used antibiotics, ciprofloxacin (CIP) and tetracycline (TC), by the ubiquitous redox soil mineral, birnessite (MnO2). Subsequently, we evaluated the impact of these transformation products on both the growth and activity of the environmental denitrifier Pseudomonas veronii. Following the reaction with birnessite, four transformation products for CIP and five for TC were identified. Remarkably, the antibacterial activity of both CIP and TC was lost upon the formation of transformation products during their interaction with birnessite. This loss of antimicrobial efficacy was associated with specific chemical transformations, such as the opening of the piperazine ring for CIP and hydroxylation and demethylation for TC. Interestingly, denitrifying activity, quantified in terms of nitrate reduction rates, remained unaffected by both CIP and TC at low concentrations that did not impact bacterial growth. However, under certain conditions, specifically at low concentrations of CIP, the second step of denitrification—nitrite reduction—was hindered, leading to the accumulation of nitrite. Our findings highlight that the transformation products induced by the mineral-mediated reactions of CIP or TC lose the initial antibacterial activity observed in the parent compounds. This research contributes valuable insights into the intricate interplay between antibiotics, redox-active minerals, and microbial activity in environmental systems. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of a copper-based layered double hydroxide (Cu-LDH) composite via the coprecipitation method. The composite material aimed to effectively remove the anionic dye "Coomassie Brilliant Blue" (CBB) and exhibit antibacterial properties against both gram-positive and gram-negative bacteria. The synthesized nanocomposites were characterized using various techniques. The adsorption of CBB dye was investigated by studying various physicochemical variables, including contact time, pH of the dye solution, and initial dye concentration. The optimal dosage and contact time for efficient CBB dye removal were determined as 0.07 g and 10 min, respectively. The results showed that Cu-LDHs exhibited a high adsorption capacity for CBB dye, with a maximum removal efficiency of 85% which could be achieved within 10 min, and the Cu-LDHs improved an experimental adsorption capacity at equilibrium qmax = 80 mg/g. The adsorption process followed a pseudo-second-order kinetic model. The Langmuir isotherm model provided a good fit to the equilibrium data, indicating monolayer adsorption. Furthermore, the antibacterial activity of Cu-LDHs was assessed against various bacterial strains using a diffusion method. The results demonstrated the inhibitory effects of Cu-LDHs and CBB-Cu-LDHs on bacterial growth at a dosage of 10 mg, indicating the potential of Cu-LDHs as antibacterial agents. The underlying mechanisms responsible for dye adsorption and antibacterial activity were discussed. [ABSTRACT FROM AUTHOR]

Purpose: The growing incidence of implant-associated infections (IAIs) caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance to antibiotics requires new therapeutic strategies. Lysostaphin has been shown to eliminate this biofilm. Own studies confirm the effectiveness in a murine model. The current study characterizes the effects of lysostaphin-coated plates in an IAI minipig model. Methods: The femur of 30 minipigs was stabilized with a five-hole plate, a bone defect was created, and in 20 cases methicillin-resistant Staphylococcus aureus was applied. Ten animals served as control group. After 14 days, local debridement, lavage, and plate exchange (seven-hole plate) were performed. Ten of the infected minipigs received an uncoated plate and 10 a lysostaphin-coated plate. On day 84, the minipigs were again lavaged, followed by euthanasia. Bacterial load was quantified by colony-forming units (CFU). Immunological response was determined by neutrophils, as well as interleukins. Fracture healing was assessed radiologically. Results: CFU showed significant difference between infected minipigs with an uncoated plate and minipigs with a lysostaphin-coated plate (p = 0.0411). The infection-related excessive callus formation and calcification was significantly greater in the infected animals with an uncoated plate than in animals with a lysostaphin-coated plate (p = 0.0164/p = 0.0033). The analysis of polymorphonuclear neutrophils and interleukins did not reveal any pioneering findings. Conclusion: This study confirms the minipig model for examining IAI. Furthermore, coating of plates using lysostaphin could be a promising tool in the therapeutic strategies of IAI. Future studies should focus on coating technology of implants and on translation into a clinical model. [ABSTRACT FROM AUTHOR]

Biofertilizers are a sustainable solution for the adverse biogeochemical impacts exerted by synthetic agrochemicals. The application of biofertilizers is an eco-friendly approach to facilitate plant growth and development. Biofertilizers are mainly composed of living or dormant microbes, which are usually applied to the soil. These microbes encourage plant growth by a wide variety of mechanisms which includes phytohormone production, nutrient solubilization, biocontrol ability, etc. In the present study, bacterial cultures were isolated from nutrient-rich sample sources and screened for plant growth-promoting (PGP) traits. After several PGP trait screenings; two bacterial consortia that could aid the growth and development of plants were formulated. Further, these screening results were validated by applying selected bacterial strains and the prepared consortia on tomato plants (Solanum lycopersium). The growth parameters were evaluated at the plant's germinative, vegetative, and reproductive stages. The biochemical characteristics under the experimental conditions were also examined at various intervals. The results revealed that both our consortia were able to stimulate the growth and development of the host plant. Hence, the formulated bacterial combinations have real potential to become ecologically sustainable biofertilizers. [ABSTRACT FROM AUTHOR]

Bacterial reduction of hexavalent chromium (VI) to chromium (III) is a sustainable bioremediation approach. However, the Cr(VI) containing wastewaters are often characterized with complex conditions such as high salt, alkaline pH and heavy metals which severely impact the growth and Cr(VI) reduction potential of microorganisms. This study investigated Cr(VI) reduction under complex haloalkaline conditions by an Alteromonas sp. ORB2 isolated from aerobic granular sludge cultivated from the seawater-microbiome. Optimum growth of Alteromonas sp. ORB2 was observed under haloalkaline conditions at 3.5–9.5% NaCl and pH 7–11. The bacterial growth in normal culture conditions (3.5% NaCl; pH 7.6) was not inhibited by 100 mg/l Cr(VI)/ As(V)/ Pb(II), 50 mg/l Cu(II) or 5 mg/l Cd(II). Near complete reduction of 100 mg/l Cr(VI) was achieved within 24 h at 3.5–7.5% NaCl and pH 8–11. Cr(VI) reduction by Alteromonas sp. ORB2 was not inhibited by 100 mg/L As(V), 100 mg/L Pb(II), 50 mg/L Cu(II) or 5 mg/L Cd(II). The bacterial cells grew in the medium with 100 mg/l Cr(VI) contained lower esterase activity and higher reactive oxygen species levels indicating toxicity and oxidative stress. In-spite of toxicity, the cells grew and reduced 100 mg/l Cr(VI) completely within 24 h. Cr(VI) removal from the medium was driven by bacterial reduction to Cr(III) which remained in the complex medium. Cr(VI) reduction was strongly linked to aerobic growth of Alteromonas sp. The Cr(VI) reductase activity of cytosolic protein fraction was pronounced by supplementing with NADPH in vitro assays. This study demonstrated a growth-dependent aerobic Cr(VI) reduction by Alteromonas sp. ORB2 under complex haloalkaline conditions akin to wastewaters. [ABSTRACT FROM AUTHOR]

Phage replication can be studied using various approaches, including measuring the optical density (OD) of a bacterial culture in a liquid medium in the presence of phages. A few quantitative methods are available to measure and compare the efficiency of phages by using a single index based on the analysis of OD curves. However, these methods are not always applicable to non-canonical OD curves. Using the concept of center of area (centroid), we developed a metric called Centroid Index (CI), sensitive to the trend of the growth curves (OD distribution) including bacterial regrowth, which is not considered by the methods already available. We also provide a user-friendly software to facilitate the calculation of CI. This method offers an alternative and more precise way to determine phage efficiency by considering the OD variations over time, which may help in the selection of phages for biocontrol applications. Current methods quantifying phage lytic efficacy have limits. Centroid Index quantifies efficacy via the center of area, offering more accuracy. For calculation of this index, a software called Centroid Index Calculator is presented. [ABSTRACT FROM AUTHOR]

Background: Intravitreal injections are a common ophthalmologic procedure. While infections following these injections are rare, they can lead to endophthalmitis, with potentially serious consequences. Various methods have been proposed to prevent endophthalmitis, including the use of antisepsis and antibiotics in patient preparation. Purpose: To evaluate the antiseptic efficacy of aqueous chlorhexidine (CHX) and povidone-iodine (PI) when used alone and in combination with lidocaine gel (LG) in vitro. Methods: Two independent experimental trials were conducted. The first trial determined the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of CHX and PI against six bacterial strains. The second trial evaluated the bactericidal efficacy of the antiseptic agents (CHX 0.1% and PI 5%) and their combination with LG against the same bacterial strains. Results: CHX was more effective than PI in reducing the number of colonies forming units (cfus) of the tested bacteria. The order in which the antiseptic and LG were administered affected their effectiveness, with CHX administered before LG resulting in greater reduction of bacterial growth. Conclusions: CHX 0.1% is more effective than PI 5% as an antiseptic agent. Application of CHX and PI prior to the use of lidocaine gel results in a more effective reduction of microorganisms. [ABSTRACT FROM AUTHOR]

Purpose: Surgical site infection (SSI) is a serious complication after cranioplasty. Due to the relatively frequent occurrence of post-cranioplasty SSI, the utility of autologous bone flap swab cultures surrounding cryopreservation as a reliable predictor has been the subject of an ongoing debate. This bicentric study aims to contribute to this topic by conducting an in-depth analysis of bone flaps obtained via decompressive craniectomies. This study had three major aims: assessments of 1) bacterial contamination of bone flaps after decompressive craniotomy, 2) impact of cryoconservation on contamination rates and 3) potential effectiveness of anti-infective treatment to reduce the germ load prior to cranioplasty. Methods: Cryopreserved bone flaps from two centers were used. Microbiological cultivations of swabs prior to and after cryopreservation were taken and assessed for aerobic and anaerobic growth over a 14-day incubation period. Additionally, in a subset of bone flaps, swab testing was repeated after thorough rinsing with an anti-infectant (octenidine-phenoxyethanol) followed by saline. Results: All 63 bone flaps (patients median age at surgery: 59 years) were obtained via decompressive craniectomies. Swabs done prior to cryopreservation revealed a 54% infection rate with Propionibacterium acnes being the most common microorganism in 65% of those cases. After thorough disinfection of the preserved bone flaps, all but one case showed no bacterial growth in swab testing. Furthermore, no relevant risk factors for bacterial contamination could be identified. Conclusion: This retrospective study showed the common presence of bacterial growth in cryopreserved bone flaps before and after freezing. Rinsing with octenidine-phenoxyethanol and saline effectively prevented bacterial growth in a notable percentage of cases, suggesting a potential strategy to reduce contamination. However, persistent bacterial growth in some cases underscores the need for further research to optimize antiseptic measures during autologous cranioplasty. [ABSTRACT FROM AUTHOR]

Growth rate maximization is an important fitness strategy for microbes. However, the wide distribution of slow-growing oligotrophic microbes in ecosystems suggests that rapid growth is often not favored across ecological environments. In many circumstances, there exist trade-offs between growth and other important traits (e.g., adaptability and survival) due to physiological and proteome constraints. Investments on alternative traits could compromise growth rate and microbes need to adopt bet-hedging strategies to improve fitness in fluctuating environments. Here we review the mechanistic role of trade-offs in controlling bacterial growth and further highlight its ecological implications in driving the emergences of many important ecological phenomena such as co-existence, population heterogeneity and oligotrophic/copiotrophic lifestyles. Trade-offs play a key role in controlling bacterial growth and shaping microbial phenotypes, which further drives the emergence of ecologically relevant phenomena including co-existence, population heterogeneity and oligotrophic/copiotrophic lifestyles. [ABSTRACT FROM AUTHOR]

Proteolysis-targeting chimeras (PROTACs) represent a new therapeutic modality involving selectively directing disease-causing proteins for degradation through proteolytic systems. Our ability to exploit targeted protein degradation (TPD) for antibiotic development remains nascent due to our limited understanding of which bacterial proteins are amenable to a TPD strategy. Here, we use a genetic system to model chemically-induced proximity and degradation to screen essential proteins in Mycobacterium smegmatis (Msm), a model for the human pathogen M. tuberculosis (Mtb). By integrating experimental screening of 72 protein candidates and machine learning, we find that drug-induced proximity to the bacterial ClpC1P1P2 proteolytic complex leads to the degradation of many endogenous proteins, especially those with disordered termini. Additionally, TPD of essential Msm proteins inhibits bacterial growth and potentiates the effects of existing antimicrobial compounds. Together, our results provide biological principles to select and evaluate attractive targets for future Mtb PROTAC development, as both standalone antibiotics and potentiators of existing antibiotic efficacy. Efforts to apply targeted protein degradation for antibiotic development are limited by our understanding of prokaryotic protein degradation. Here, the authors establish a chemical-genetic platform and predictive model to determine the degradation potential of essential mycobacterial proteins. [ABSTRACT FROM AUTHOR]

Long-chain fatty acids with antimicrobial properties are abundant on the skin and mucosal surfaces, where they are essential to restrict the proliferation of opportunistic pathogens such as Staphylococcus aureus. These antimicrobial fatty acids (AFAs) elicit bacterial adaptation strategies, which have yet to be fully elucidated. Characterizing the pervasive mechanisms used by S. aureus to resist AFAs could open new avenues to prevent pathogen colonization. Here, we identify the S. aureus lipase Lip2 as a novel resistance factor against AFAs. Lip2 detoxifies AFAs via esterification with cholesterol. This is reminiscent of the activity of the fatty acid-modifying enzyme (FAME), whose identity has remained elusive for over three decades. In vitro, Lip2-dependent AFA-detoxification was apparent during planktonic growth and biofilm formation. Our genomic analysis revealed that prophage-mediated inactivation of Lip2 was rare in blood, nose, and skin strains, suggesting a particularly important role of Lip2 for host – microbe interactions. In a mouse model of S. aureus skin colonization, bacteria were protected from sapienic acid (a human-specific AFA) in a cholesterol- and lipase-dependent manner. These results suggest Lip2 is the long-sought FAME that exquisitely manipulates environmental lipids to promote bacterial growth in otherwise inhospitable niches. This study on how Staphylococcus aureus manipulates host-derived fatty acids reveals that a bacteriallipase (Lip2) converts toxic fatty acids and cholesterol into innocuous cholesteryl esters. [ABSTRACT FROM AUTHOR]

Introduction: Patients and physicians often underestimate cat bite injuries. The deep and narrow wound seals quickly and provides an environment for the inoculated saliva and bacteria. Interestingly, the literature reports no bacterial growth in the microbiological workup of wound swaps in up to 43%. The time between bite injury and the first clinical presentation, the start of antibiotic treatment and surgical debridement might affect these findings. Therefore, the current project examines if (1) these factors impact the outcome of microbiological results following cat bite injuries and (2) the detection of bacterial growth leads to higher complication rates, longer hospital stays, longer total treatment time, or higher total treatment costs. Materials and methods: This single-center retrospective study analyzed data from 102 adult patients. All patients received antibiotic and surgical treatment following a cat bite injury. Microbiological samples were collected during surgery in all cases. The time from the bite incident to the first presentation, beginning of antibiotic administration, and surgical debridement was calculated. Demographic data, complication rate, length of hospital stay, total treatment time, and total treatment costs were recorded. (1) A generalized linear model was fitted using the microbiological outcome as the dependent variable. (2) Two groups (negative or positive microbiological results) were formed and statistically compared. Results: The median age was 50 (SD 16), and 72% were female. (1) The time from the bite incident to the first clinical presentation, antibiotic administration, or surgical treatment was not associated with the outcome of the microbiological result. (2) No significant differences were observed between the two groups. Conclusions: Our data do not suggest that early antibiotic administration or delayed surgical treatment affects the outcome of the microbiological workup following cat bite injuries to the hand and forearm. The microbiological outcome did not affect the complication rate, treatment time, and total treatment costs. [ABSTRACT FROM AUTHOR]

This paper reports data on the structural and production characteristics of bacterioplankton in the western Kara Sea at the beginning and middle of summer. On the slope of the St. Anna Trough, the average prokaryote abundance in the water column was 594–708 × 103 cells mL−1 (26.4–36.5 mgC m–3) in June and 247–517 × 103 cells mL−1 (12–28 mgC m–3) at the beginning of August. On the transect along the Novaya Zemlya archipelago, the average bacterioplankton abundance in the water column was 186–554 × 103 cells mL−1 (8.5–30 mgC m–3) within a week after the seasonal ice retreat and 169–443 × 103 cells mL−1 (8–21 mgC m–3) in midsummer. The specific bacterial growth rate did not exceed 1.28 day–1; high values were observed in the upper warm water layer, above the halocline, and also in near-bottom water. At the beginning of summer, the bacterioplankton production tended to decrease in the northeast direction. The prokaryote abundance distribution was associated with water temperature and oxygen saturation possibly as an indirect indicator of the past phytoplankton bloom. [ABSTRACT FROM AUTHOR]

Chronic non-healing wounds significantly strain modern healthcare systems, affecting 1–2% of the population in developed countries with costs ranging between $28.1 and $96.8 billion annually. Additionally, it has been established that chronic wounds resulting from comorbidities, such as peripheral vascular disease and diabetes mellitus, tend to be polymicrobial in nature. Treatment of polymicrobial chronic wounds with oral and IV antibiotics can result in antimicrobial resistance, leading to more difficult-to-treat wounds. Ideally, chronic ulcers would be topically treated with antibiotic combinations tailored to the microbiome of a patient's wound. We have previously shown that a topical collagen-rich hydrogel (cHG) can elute single antibiotics to inhibit bacterial growth in a manner that is nontoxic to mammalian cells. Here, we analyzed the microbiology of cultures taken from human patients diagnosed with diabetes mellitus suffering from chronic wounds present for more than 6 weeks. Additionally, we examined the safety of the elution of multiple antibiotics from collagen-rich hydrogel in mammalian cells in vivo. Finally, we aimed to create tailored combinations of antibiotics impregnated into cHG to successfully target and treat infections and eradicate biofilms cultured from human chronic diabetic wound tissue. We found that the majority of human chronic wounds in our study were polymicrobial in nature. The elution of multiple antibiotics from cHG was well-tolerated in mammalian cells, making it a potential topical treatment of the polymicrobial chronic wound. Finally, combinations of antibiotics tailored to each patient's microbiome eluted from a collagen-rich hydrogel successfully treated bacterial cultures isolated from patient samples via an in vitro assay. [ABSTRACT FROM AUTHOR]

The main goal of this study was to investigate in vitro the antibacterial action of chitosan (CS), in various physical forms (film, bead, powder and solution), against selected bacteria including Escherichia coli, Staphylococcus epidermidis, Proteus mirabilis and Pseudomonas aeruginosa. For this purpose, chitosan was produced by N-deacetylation of chitin under different alkaline conditions. Degree of deacetylation (DDA), molecular weight and viscosity of each form of chitosan were determined. The functional groups of chitosan were confirmed by Fourier Transform Infrared Spectroscopy and the degradation temperatures by Differential Scanning Calorimetry (DSC). Chitosan with high DDA (95%), molecular weight (149.01 KDa) and viscosity (0.2498 dL/g) was obtained by deacetylation with 50% of sodium hydroxide at 90 °C for 4 h. The antibacterial test results demonstrated the presence of significant antibacterial action of soluble chitosan against the tested pathogenic bacteria. In addition, the bacterial growth showed a considerable decrease in bacterial biomass after addition of CS, the resistance of the studied bacterial strains against soluble CS decreased in the following order: E. coli > P. mirabilis > S. epidermidis and their action process was bacteriostatic rather than bactericidal. [ABSTRACT FROM AUTHOR]