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Asymmetric seasonal warming trends are evident across terrestrial ecosystems, with winter temperatures rising more than summer ones. Yet, the impact of such asymmetric seasonal warming on soil microbial carbon metabolism and growth remains poorly understood. Using 18 O isotope labeling, we examined the effects of a decade-long experimental seasonal warming on microbial carbon use efficiency (CUE) and growth in alpine grassland ecosystems. Moreover, the quantitative stable isotope probing with 18 O-H 2 O was employed to evaluate taxon-specific bacterial growth in these ecosystems. Results show that symmetric year-round warming decreased microbial growth rate by 31% and CUE by 22%. Asymmetric winter warming resulted in a further decrease in microbial growth rate of 27% and microbial CUE of 59% compared to symmetric year-round warming. Long-term warming increased microbial carbon limitations, especially under asymmetric winter warming. Long-term warming suppressed the growth rates of most bacterial genera, with asymmetric winter warming having a stronger inhibition on the growth rates of specific genera (e.g., Gp10 , Actinomarinicola , Bosea , Acidibacter , and Gemmata ) compared to symmetric year-round warming. Bacterial growth was phylogenetically conserved, but this conservation diminished under warming conditions, primarily due to shifts in bacterial physiological states rather than the number of bacterial species and community composition. Overall, long-term warming escalated microbial carbon limitations, decreased microbial growth and CUE, with asymmetric winter warming having a more pronounced effect. Understanding these impacts is crucial for predicting soil carbon cycling as global warming progresses., Competing Interests: Competing interests statement:The authors declare no competing interest.

Anammox bacteria are obligate anaerobic bacteria that exist widely in nature with sufficient amounts of dissolved oxygen. However, whether anammox bacteria can grow under aerobic conditions remains unclear. In this study, we found that the production of nitrate in the anammox system under aerobic conditions was significantly higher than that under anaerobic conditions without total nitrogen loss. Anammox bacteria can grow by oxidizing nitrite and dehydrogenating hydrazine to produce electrons for carbon fixation. The hydrazine dehydrogenase in anammox bacteria was inhibited under aerobic conditions, and the nitrite oxidoreductase transcription expression of anammox bacteria increased by 2.7 times compared to that under anaerobic conditions, which was the main way for anammox bacteria perform carbon fixation. DNA-stable isotope probing with 13 C bicarbonate found the existence of anammox bacteria with 13 C isotopes in aerobic cultivation, further proving that anammox bacteria can grow under aerobic condition. More than half of the pathways in glycolysis, the Wood-Ljungdahl pathway, and the tricarboxylic acid cycle were upregulated in anammox bacteria in aerobic condition. Large amounts of bacterioferritins are the important antioxidative enzymes in anammox bacteria in the aerobic environment, which contributes to their stronger oxygen adaptation than other anaerobes. This study expands our understanding of the growth mechanism of anammox bacteria as well as the oxygen adaptation strategies of obligate anaerobic bacteria.

The monitoring of life of microbial populations is of the uttermost importance in environmental and food analysis, agriculture, as well as in medicine. The duration of bacteria adaptation to new environmental conditions, its lifetime and the divisions' pace are the key information in many studies. It was found that the fully-mechanized flow analysis system based on solenoid valves and pumps, paired with a dedicated flow-through optoelectronic detector can be successfully applied for monitoring of bacteria growth. The applicability of the designed multicommutated flow analysis (MCFA) system was proved by analysis of solutions containing bacteria cells proceeded by tests of McFarland (McF) standards. The developed setup allowed modelling and simulation of microbial growth, as well as monitoring of the bacteria growth in real-time manner to be carried out. The monitor is useful for the quantitative estimation of the basic parameters of bacteria population like its size, the rate of bacteria multiplication, as well as the times of lag, log and stationary phases of microbial growth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Complex and fluid bacterial community compositions are critical to diversity, stability, and function. However, quantitative and mechanistic descriptions of the dynamics of such compositions are still lacking. Here, we develop a modularized design framework that allows for bottom-up construction and the study of synthetic bacterial consortia with different topologies. We showcase the microbial consortia design and building process by constructing amensalism and competition consortia using only genetic circuit modules to engineer different strains to form the community. Functions of modules and hosting strains are validated and quantified to calibrate dynamic parameters, which are then directly fed into a full mechanistic model to accurately predict consortia composition dynamics for both amensalism and competition without further fitting. More importantly, such quantitative understanding successfully identifies the experimental conditions to achieve coexistence composition dynamics. These results illustrate the process of both computationally and experimentally building up bacteria consortia complexity and hence achieve robust control of such fluid systems.

The growth and activity of bacteria have been extensively studied in nearly every environment on Earth, but there have been limited studies focusing on the air. Suspended bacteria (outside of water droplets) may stay in the atmosphere for time frames that could allow for growth on volatile compounds, including the potent greenhouse gas methane. We investigated the ability of aerosolized methanotrophic bacteria to grow on methane in the airborne state in rotating gas-phase bioreactors. The physical half-life of the aerial bacterium-sized particles was 3 days. To assess the potential for airborne growth, gas-phase bioreactors containing the aerosolized cultures were amended with 1,500 ppmv 13 CH 4 or 12 CH 4 . Three of seven experiments demonstrated 13 C incorporation into DNA, indicating growth in air. Bacteria associated with the genera Methylocystis and Methylocaldum were detected in 13 C-DNA fractions, thus indicating that they were synthesizing new DNA, suggesting growth in air. We conclude that methanotrophs outside of water droplets in the air can potentially grow under certain conditions. Based on our data, humidity seems to be a major limitation to bacterial growth in air. Furthermore, low biomass levels can pose problems for detecting 13 C-DNA synthesis in our experimental system. IMPORTANCE Currently, the cellular activities of bacteria in the airborne state outside of water droplets have not been heavily studied. Evidence suggests that these airborne bacteria produce ribosomes and metabolize gaseous compounds. Despite having a potentially important impact on atmospheric chemistry, the ability of bacteria in the air to metabolize substrates such as methane is not well understood. Demonstrating that bacteria in the air can metabolize and grow on substrates will expand knowledge about the potential activities and functions of the atmospheric microbiome. This study provides evidence for DNA synthesis and, ultimately, growth of airborne methanotrophs.

Ecotoxicity assessments based on bacteria as model organisms are widely used for routine toxicity screening because it has the advantages of time-saving, high sensitivity, cost-effectiveness, and less ethical responsibility. Determination of ecotoxicity effect via bacterial growth can avoid the restriction of model bacteria selection and unique equipment requirements, but traditional viable cell count methods are relatively labor- and time-intensive. The Start Growth Time method (SGT) is a high-throughput and time-conserving method to determine the amount of viable bacterial cells. However, its usability and stability for ecotoxicity assessment are rarely studied. This study confirmed its applicability in terms of bacterial types (gram-positive and gram-negative), growth phases (middle exponential and early stationary phases), and simultaneous existence of dead cells (adjustment by flow cytometry). Our results verified that the stability of establishing SGT correlation is independent of the bacterial type and dead-cell portion. Moreover, we only observed the effect of growth phases on the slope value of established SGT correlation in Shewanella oneidensis, which suggests that preparing inoculum for the SGT method should be consistent in keeping its stability. Our results also elucidate that the SGT values and the live cell percentages meet the non-linear exponential correlation with high correlation coefficients from 0.97 to 0.99 for all the examined bacteria. The non-linear exponential correlation facilitates the application of the SGT method in the ecotoxicity assessment. Finally, applying the exponential SGT correlation to evaluate the ecotoxicity effect of copper ions on E. coli was experimentally validated. The SGT-based method would require about 6 to 7 h to finish the assessment and obtain an estimated EC 50 at 2.27 ± 0.04 mM. This study demonstrates that the exponential SGT correlation can be a high-throughput, time-conversing, and wide-applicable method for bacterial ecotoxicity assessment., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bacterial growth in microfluidic droplets is relevant in biotechnology, in microbial ecology, and in understanding stochastic population dynamics in small populations. However, it has proved challenging to automate measurement of absolute bacterial numbers within droplets, forcing the use of proxy measures for population size. Here we present a microfluidic device and imaging protocol that allows high-resolution imaging of thousands of droplets, such that individual bacteria stay in the focal plane and can be counted automatically. Using this approach, we track the stochastic growth of hundreds of replicate Escherichia coli populations within droplets. We find that, for early times, the statistics of the growth trajectories obey the predictions of the Bellman-Harris model, in which there is no inheritance of division time. Our approach should allow further testing of models for stochastic growth dynamics, as well as contributing to broader applications of droplet-based bacterial culture., (Creative Commons Attribution license.)

One of the most common bacterial shapes is a rod, yet we have a limited understanding of how this simple shape is constructed. While only six proteins are required for rod shape, we are just beginning to understand how they self-organize to build the micron-sized enveloping structures that define bacterial shape out of nanometer-sized glycan strains. Here, we detail and summarize the insights gained over the last 20 years into this complex problem that have been achieved with a wide variety of different approaches. We also explain and compare both current and past models of rod shape formation and maintenance and then highlight recent insights into how the Rod complex might be regulated.

Objectives/hypothesis: We aimed to determine whether there was a difference between core and surface bacteriology of Finnish adults with recurrent or chronic tonsillitis to understand whether a surface swab is worthwhile and which bacteria are involved., Study Design: Case series., Methods: Uninflamed tonsillar surface swabs and core biopsies were taken prior to and during surgery, respectively, in 103 patients aged 16 to 66 years undergoing tonsillectomy for recurrent or chronic tonsillitis. The McNemar test was used to determine differences between the surface and core in the most prevalent bacterial species., Results: Twenty-seven bacterial species were isolated in addition to normal flora and were more commonly found in the core (1.11 surface and 4.75 core bacteria isolated per patient). Viridans group streptococci were the most commonly detected bacteria, found in 88% of the patients, mainly in the core. The bacteria in general were mainly isolated from the core. Of the 10 most prevalent bacteria, only group C β-hemolytic streptococci showed no difference between detection from core and surface swabs. Other bacteria found mainly in the core include Prevotella melaninogenica, Staphylococcus aureus, and fusobacteria., Conclusions: There is discord between the surface and core bacteria. A different population of bacteria exists in the core, especially anaerobic bacteria, suggesting that a core sample may be useful in evaluating recurrent and chronic tonsillitis., Level of Evidence: 4 Laryngoscope, 2019., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

This paper studied stagnation-induced changes of disinfectant and bacteria using an orthogonal test and kinetic analysis, and then proposed a disinfection strategy. Tap water from a drinking water distribution system and ultrafiltrated water were collected and disinfected with four disinfectants (concentrations were set 0.2-1 mg/L as Cl 2 . The study had several findings. First, disinfectants expanded lag phases and shortened generation times of the microbiome. Reduction in culturability, substrate responsiveness, respiratory activity, membrane potential and integrity subsequently occurred with increasing disinfection concentration. Second, the disinfectant decay rate decreased with initial disinfection concentration, and the effective disinfection phase (heterotrophic plate count (HPC) was less than 100 cfu/mL) was longer in water samples with lower organic matter. Moreover, the disinfection process was divided into an effective phase and an invalid phase (HPC>100 cfu/mL). Then a disinfection efficiency model was built and the regulation of disinfection by-products (DBPs) production was studied in chlorinated water samples, which provides a general method for other disinfectant studies. The average trihalomethanes (THMs) production during the effective phase (marked as THM/t h ) and THMs production during the invalid phase (marked as ΔTHM) were proposed to evaluate the DBPs production. The level of THM/t h and ΔTHM were lower in ultrafiltrated water than those in tap water. THM/t h were negatively correlated with initial chlorine concentration while ΔTHM were positively correlated with initial chlorine concentration. Finally, for the purpose of raising disinfection efficiency and decreasing DBPs, we propose periodic pulse disinfection., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Beneficial effects of cold atmospheric argon plasma (CAAP) on wound healing and its capacity for bacterial decontamination has recently been documented. First, in vivo studies in small animals did not prove any decontamination effect in canine bite wounds. The present study evaluated the overall decontamination effect of CAAP for different bacteria frequently encountered in canine bite wounds with respect to growth phase, initial bacteria concentration and treatment duration. Standard strains of Escherichia (E.) coli, Staphylococcus (S.) pseudintermedius, S. aureus, Streptococcus (S.) canis, Pseudomonas (P.) aeruginosa and Pasteurella multocida were investigated. To evaluate the influence of the bacterial growth phase, each bacterium was incubated for three and eight hours, before CAAP treatment. Three different bacterial concentrations were created per bacterium and growth phase, and were exposed to CAAP for 30 s, 1 min and 2 min. CAAP treatment resulted in acceptable decontamination rates (range 98.9-99.9%) in all bacteria species in vitro; however, differences in susceptibility were detected. Decontamination rate was mainly influenced by initial bacterial concentration and treatment time. Growth phase only influenced decontamination in S. pseudintermedius. Treatment time significantly (P < .05) correlated with the decontamination rate in E. coli, S. canis and S. aureus, with an exposure time of 2 min being most effective. Initial bacterial concentration significantly (P < .05) influenced decontamination in Pasteurella multocida and P. aeruginosa, in which treatment time was not as important. CAAP exerts effective antibacterial activity against the tested bacteria strains in vitro, with species specific effects of treatment time, growth phase and concentration., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Microorganisms have evolved complex strategies for controlling the distribution of available resources over cellular functions. Biotechnology aims at interfering with these strategies, so as to optimize the production of metabolites and other compounds of interest, by (re)engineering the underlying regulatory networks of the cell. The resulting reallocation of resources can be described by simple so-called self-replicator models and the maximization of the synthesis of a product of interest formulated as a dynamic optimal control problem. Motivated by recent experimental work, we are specifically interested in the maximization of metabolite production in cases where growth can be switched off through an external control signal. We study various optimal control problems for the corresponding self-replicator models by means of a combination of analytical and computational techniques. We show that the optimal solutions for biomass maximization and product maximization are very similar in the case of unlimited nutrient supply, but diverge when nutrients are limited. Moreover, external growth control overrides natural feedback growth control and leads to an optimal scheme consisting of a first phase of growth maximization followed by a second phase of product maximization. This two-phase scheme agrees with strategies that have been proposed in metabolic engineering. More generally, our work shows the potential of optimal control theory for better understanding and improving biotechnological production processes.

The exogenous gene expression and its impacts on the bacterial population are important to study quorum sensing systems and synthetic biology industry. However, the behavior of exogenous protein expressing bacteria remains poorly understood. To find out which factors are playing a critical role in the growth of population and exogenous gene expression, we measured Lux-type receptor-regulated exogenous gene expression under the induction of N-acyl homoserine lactone (N-AHL) signaling molecules and impacts on the bacterial population dynamics after such stimulation. To analyze the cause of fitness burden of bacteria, we set up a hypothetical mathematical model. Previous studies often arrogate this phenomenon to the synthesis cost and the toxicity of N-AHL signaling molecule. However, we suggested another possible cause of the fitness burden.

The human gut microbiota is highly dynamic, and host physiology and diet exert major influences on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework. This can generate predictions of how changes in different host factors influence microbiota composition. For instance, hydrodynamic forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition. This can be mechanistically explained by their effect on colonic pH which directly affects microbiota competition for food. In this addendum, we describe the underlying analysis in more detail. In particular, we discuss the mixing dynamics of luminal content by wall contractions and its implications for bacterial growth and density, as well as the broader implications of our insights for the field of gut microbiota research.

Background: To prevent cross infection the surgical team perform preoperative hand disinfection before dressed in surgical gowns and gloves. Preoperative hand disinfection does not make hands sterile and the surgical glove cuff end has been regarded as a weak link, since it is not a liquid-proof interface. The aims were to investigate if there were differences in bacterial growth and recolonization of hands between operating room nurses and non-health care workers as well as to investigate if bacterial growth existed at the surgical glove cuff end during surgery., Methods: This pilot project was conducted as an exploratory comparative clinical trial. Bacterial cultures were taken from the glove and gown interface and at three sites of the hands of 12 operating room nurses and 13 non-health care workers controls directly after preoperative hand disinfection and again after wearing surgical gloves and gowns. Colony forming units were analysed with Mann-Whitney U test and Wilcoxon Sign Ranks test comparing repeated measurements. Categorical variables were evaluated with chi-square test or Fisher's exact test., Results: Operating room nurses compared to non-health care workers had significant higher bacterial growth at two of three culture sites after surgical hand disinfection. Both groups had higher recolonization at one of the three culture sites after wearing surgical gloves. There were no differences between the groups in total colony forming units, that is, all sampling sites. Five out of 12 of the operating room nurses had bacterial growth at the glove cuff end and of those, four had the same bacteria at the glove cuff end as found in the cultures from the hands. Bacteria isolated from the glove cuff were P. acnes, S. warneri, S. epidermidis and Micrococcus species, the CFU/mL ranged from 10 to 40., Conclusions: There were differences in bacterial growth and re-colonization between the groups but this was inconclusive. However, bacterial growth exists at the glove cuff and gown interface, further investigation in larger study is needed, to build on these promising, but preliminary, findings., Trial Registration: Trial registration was performed prospectively at Research web (FOU in Sweden, 117,971) 14/01/2013, and retrospectively at ClinicalTrials.gov ( NCT02359708 ). 01/27/2015.

The present study evaluated whether two different antimicrobial peptides (AMP): porcine beta defensins-1 (PBD1) and -2 (PBD2) at three concentrations (1.5 μM, 3 μM and 5 μM) could be a suitable alternative to antibiotics in liquid-stored boar semen. Two separate experiments were conducted with liquid-stored boar semen preserved at 17 °C for 9-10 days. In the first one, we evaluated the impact of adding three concentrations of each AMP on the bacterial growth and sperm quality of boar semen stored for 10 days. In the second experiment, the ability of these AMPs to control bacterial growth was determined over a 9-day period, following artificial inoculation with Escherichia coli at 10 7 and 10 8  CFU mL -1 . In both experiments, sperm viability was assessed through flow cytometry, sperm motility was determined with Computer Assisted Sperm Analysis (CASA) and the inhibitory effect on microbial growth was evaluated by bacteria culture on Luria Bertani agar. PBD1 and PBD2 were found to significantly (P < 0.05) decrease sperm motility at 5 μM (% total motile spermatozoa at day 10, Control: 31.6% ± 1.2% vs. PBD1: 6.5% ± 0.3% and PBD2: 5.6% ± 0.4%). Although the highest inhibitory effect on bacterial growth was observed at 3 μM (day 10, PBD1: 1.4 × 10 6  ± 6.2 × 10 5  CFU mL -1 and PBD2: 9.1 × 10 5  ± 2.4 × 10 5  CFU mL -1 ) and 5 μM (day 10, PBD1: 1.2 × 10 5  ± 5.1 × 10 4  CFU mL -1 ; PBD2: 8.7 × 10 4  ± 2.9 × 10 4  CFU mL -1 ), the control with antibiotic was found to be more effective (day 10, 8.3 × 10 3  ± 1.6 × 10 3  CFU mL -1 ). In conclusion, PBD1 and PBD2 may be added to antibiotic-free extenders for boar semen at a concentration of 3 μM, but do not completely control all bacterial growth., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The objectives of the current study were to investigate the fate of microbial indicators [aerobic plate counts (APC), total coliforms (TC), and lactic acid bacteria (LAB)] in commercial salted napa cabbages during storage conditions at different temperatures (5, 22, and 30 °C, for up to 72 h) and to develop a predictive growth model using the modified Gompertz equation to determine shelf life. Microbial population sizes (initial log CFU g -1 : APC, 5.1; TC, 3.0; LAB, 3.7) remained stable at 5 °C, but rapidly increased by 2-4 log CFU g -1 within 12 h at 22 and 30 °C; furthermore, the pH of salted napa cabbages decreased significantly (P < 0.05: initial pH 6.3; final pH 4.1-4.4) due to LAB fermentation. The pH showed a negative correlation with all bacterial groups and did not prevent the growth of TC during storage. According to the modified Gompertz model (R 2 ≧ 0.97), the highest μ max was observed for LAB at 30 °C [0.61 log CFU h -1 ], while the lowest was noted for TC at 5 °C [0.04 log CFU h -1 ]. Shelf-life was determined using APC (7.7 log CFU g -1 ) and LAB (6.0 log CFU g -1 ) limits; the microbiological acceptability period of salted napa cabbage was predicted to be 12.6 and 9.3 h at 22 and 30 °C, respectively. Thus, consumers should use the product within 12 h of storage at room temperature (more quickly in the summer (9 h)), or store it in a refrigerator. The presented research proposes a shelf-life modeling of commercial salted napa cabbages, which may be used as a scientific basis for product quality control and issuing appropriate guidance for consumer use at home., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Bronchoscopic valve implantation is an established treatment in selected patients with severe lung emphysema. There is evidence in literature of increased bacterial colonization of various implants. So far, it is unclear if an increased bacterial colonization can also be observed after endoscopic valve therapy., Methods: Retrospective analysis of patients with examination of the bronchial secretions for presence or change of bacterial growth before and after valve implantation., Results: Overall, 144 patients who underwent bronchoscopic follow-up after valve implantation were included in this analysis. Prior to valve placement, only 7 out of 144 consecutive emphysema patients (5%) presented with evidence of bacterial colonization, whereas 137 patients (95%) showed no bacterial growth prior to valve placement. One hundred seven out of the 137 patients (78%) showed new bacterial growth after valve implantation. Almost 38% of the patients who presented with a new bacterial growth had evidence of Viridans streptococci , Rothia mucilaginousa and Neisseria species simultaneously, as bacterial colonization. Pathogenic bacterial growth was recorded for Staphylococcus aureus (18%), Pseudomonas aeruginosa (13%) and Stenotrophomonas maltophilia (9%) microorganisms. There was also a significant bacterial growth by Moraxella catarrhalis (26%) and anaerobic bacteria (23%), especially in patients with complete atelectasis after successful endoscopic lung volume reduction. For all of the 7 patients, the presented initial bacterial colonization showed a change in the flora after bronchoscopy valve implantation., Conclusion: In this study we observed an increased bacterial colonization in the long term after valve implantation. This finding needs further evaluation regarding its possible clinical relevance but should be taken into consideration in the follow-up of these patients., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Transfer-tRNAs (tRNAs) are central entities for translation that deliver amino acids to the ribosome to translate genetic information in an mRNA-template dependent manner. Recent discoveries from our laboratory show that in E. coli and B. licheniformis, some tRNAs are poorly charged despite the plentiful intracellular cognate amino acid. Specifically, tRNAs carrying amino acids that exert toxicity and inhibit bacterial growth when added separately to the growth medium are poorly charged. Here, we discuss various evolutionary strategies different bacterial cells have adopted to precisely hone the competition between amino acid utilization for translation and proliferation and combat the inhibitory effect toward maximizing bacterial fitness. These data add a new twist to the amino acid flux models and to our understanding of the complex intimate link between dynamics of translation and bacterial growth.

Flavonoids, polyphenolic compounds present in many food products, affect growth of different bacterial species when tested as purified or synthetic substances. They can also influence gene expression in human cells, like fibroblasts. Here, we asked if soy isoflavone extracts, commonly used in many products sold as anti-menopausal dietary supplements, influence bacterial growth similarly to a synthetic isoflavone, genistein. Four commercially available products were tested in amounts corresponding to genistein concentrations causing inhibition of growth of Vibrio harveyi (a model bacterium sensitive to this isoflavone) and Escherichia coli (a model bacterium resistant to genistein). Differential effects of various extracts on V. harveyi and E. coli growth, from stimulation, to no changes, to inhibition, were observed. Moreover, contrary to genistein, the tested extracts caused a decrease (to different extent) in viability of human dermal fibroblasts. These results indicate that effects of various soy isoflavone extracts on bacterial growth and viability of human cells are different, despite similar declared composition of the commercially available products.

The hok/sok locus has been shown to enhance the growth of bacteria in adverse growth conditions such as high temperature, low starting-culture densities and antibiotic treatment. This is in addition to their well-established plasmid-stabilization effect via post-segregational killing of plasmid-free daughter cells. It delays the onset of growth by prolonging the lag phase of bacterial culture, and increases the rate of exponential growth when growth eventually begins. This enables the cells adapt to the prevailing growth conditions and enhance their survival in stressful conditions. These effects functionally complement defective SOS response mechanism, and appear analogous to the growth effects of FtsZ in the SOS pathway. In this study, the role of FtsZ in the hok/sok-induced changes in bacterial growth and cell division was investigated. Morphologic studies of early growth-phase cultures and cells growing under temperature stress showed elongated cells typical of FtsZ inhibition/deficiency. Both ftsZ silencing and over-expression produced comparable growth effects in control cells, and altered the growth changes observed otherwise in the hok/sok + cells. These changes were diminished in SOS-deficient strain containing mutant FtsZ. The involvement of FtsZ in the hok/sok-induced growth changes may be exploited as drug target in host bacteria, which often propagate antibiotic resistance elements., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Cell phones and electronic appliances and devices are inseparable from most people in modern society and the electromagnetic field (EMF) from the devices is a potential health threat. Although the direct health effect of a cell phone and its radiofrequency (RF) EMF to human is still elusive, the effect to unicellular organisms is rather apparent. Human microbiota, including skin microbiota, has been linked to a very significant role in the health of a host human body. It is important to understand the response of human skin microbiota to the RF-EMF from cell phones and personal electronic devices, since this may be one of the potential mechanisms of a human health threat brought about by the disruption of the intimate and balanced host-microbiota relationship. Here, we investigated the response of both laboratory culture strains and isolates of skin bacteria under static magnetic field (SMF) and RF-EMF. The growth patterns of laboratory cultures of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus epidermidis under SMF were variable per different species. The bacterial isolates of skin microbiota from 4 subjects with different cell phone usage history also showed inconsistent growth responses. These findings led us to hypothesize that cell phone level RF-EMF disrupts human skin microbiota. Thus, the results from the current study lay ground for more comprehensive research on the effect of RF-EMF on human health through the human-microbiota relationship.

This Research Communication explores the usefulness of predictive modelling to explain bacterial behaviour during cooling. A simple dynamic lag phase model was developed and validated. The model takes into account the effect of the cooling profile on the lag phase and growth in bulk tank milk. The time before the start of cooling was the most critical and should not exceed 1 h. The cooling rate between 30 and approximately 10 °C was the second most critical period. Cooling from 30 to 10 °C within 2 h ensured minimal growth of psychrotrophic bacteria in the milk. The cooling rate between 10 and 4 °C (the slowest phase of cooling) was of surprisingly little importance. Given a normal cooling profile to 10 °C, several hours of prolonged cooling time made practically no difference in psychrotrophic counts. This behaviour can be explained by the time/temperature dependence of the work needed by the bacteria to complete the lag phase at low temperature. For milk quality advisors, it is important to know that slow cooling below 10 °C does not result in high total counts of bacteria. In practice, slow cooling is occasionally found at farms with robotic milking. However, when comparing psychrotrophic growth in bulk milk tanks designed for robotic milking or conventional milking, the model predicted less growth for robotic milking for identical cooling profiles. It is proposed that due to the different rates of milk entering the tank, fewer bacteria will exit the lag phase during robotic milking and they will be more diluted than in conventional milking systems. At present, there is no international standard that specifies the cooling profile in robotic systems. The information on the insignificant effect of the cooling rate below 10 °C may be useful in the development of a standard.

Coalho is a semihard medium- to high-moisture cheese produced in various states in the northeastern region of Brazil. This study was conducted to predict the growth kinetics (maximum growth rate, Grmax) of Escherichia coli, Listeria monocytogenes, Salmonella, and Staphylococcus aureus using the ComBase predictor with various combinations of temperature, pH, and water activity (a w ) in commercial Coalho cheese samples. The growth of two antibiotic-resistant derivative strains of L. monocytogenes (parental strains ATCC 19115 and ATCC 7644) and S. aureus (parental strains ATCC 13565 and ATCC 19095) was measured in commercial Coalho cheese samples during 14 days of storage as a function of the initial contamination level (3 and 5 log CFU/g) and storage temperature (7.5 and 12°C). The highest Grmax values predicted by ComBase under the various conditions of temperature, pH, and a w were for L. monocytogenes (0.006 to 0.065 log CFU/g/h) and S. aureus (0.003 to 0.048 log CFU/g/h). The Grmax values predicted by ComBase for E. coli and Salmonella were 0.007 to 0.026 and 0.008 to 0.041 log CFU/g/h, respectively. An experimental challenge in Coalho cheese revealed that the populations of all tested antibiotic-resistant derivative strains of L. monocytogenes and S. aureus increased (>0.5 log CFU/g) by day 14 of storage at 7.5 or 12°C. L. monocytogenes and S. aureus had higher Grmax values in cheese samples stored at 12°C than those stored at 7.5°C. The ComBase growth predictions under the temperature, pH, and a w conditions in commercial Coalho cheese samples were generally fail-safe for predicting the growth of L. monocytogenes and S. aureus in the actual product. These results indicate that Coalho cheese has pH and a w characteristics that allow the growth of E. coli, L. monocytogenes, Salmonella, and S. aureus. These cheeses are typically stored at temperatures that do not prevent the growth of these bacteria.

Protocol changes prompted by the Joint Commission mandating intravenous (IV) fluid bags to be used within 1 hour of spiking because of possible bacterial contamination have sparked clinical and economic concerns. This study investigated the degree of bacterial growth in which samples were obtained from spiked IV fluid bags at the time of spiking and 1, 2, 4, and 8 hours after spiking. No bacterial growth occurred in any of the 80 bags of Lactated Ringer's (LR) IV solutions sampled. This study demonstrated that LR IV bags do not support any bacterial growth for up to 8 hours after spiking., (Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Negative pressure wound therapy (NPWT) has shown great advantages in the management of a wide range of clinical problems such as wound or chronic wound healing; open wounds with exposed bone, nerve, or tendon; and orthopaedic implants and related infection in the orthopaedics field. Even though it has shown positive efficacy in treating infection (wound infection or orthopaedic implant infection), its molecular mechanisms of action remain unclear and require further exploration. Since NPWT is widely used in the clinical setting, a comprehensive understanding of its biological effect will assist in appropriate clinical application. This review summarises the biological effect of NPWT on bacteria and cell growth as well as the possible mechanisms associated with NPWT applied in wound healing. We also highlight novel antibacterial dressings for NPWT. PubMed, and Web of Science database searches were conducted. Several search terms were used including negative pressure wound therapy, bacterial growth, growth factor, wound healing, dressing. All databases were searched from inception to 2015, references that lacked original resarch were eliminated.

The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the "minigut." This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction-diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon., Competing Interests: The authors declare no conflict of interest.

Background: Combination treatment is increasingly used to fight infections caused by bacteria resistant to two or more antimicrobials. While multiple studies have evaluated treatment strategies to minimize the emergence of resistant strains for single antimicrobial treatment, fewer studies have considered combination treatments. The current study modeled bacterial growth in the intestine of pigs after intramuscular combination treatment (i.e. using two antibiotics simultaneously) and sequential treatments (i.e. alternating between two antibiotics) in order to identify the factors that favor the sensitive fraction of the commensal flora. Growth parameters for competing bacterial strains were estimated from the combined in vitro pharmacodynamic effect of two antimicrobials using the relationship between concentration and net bacterial growth rate. Predictions of in vivo bacterial growth were generated by a mathematical model of the competitive growth of multiple strains of Escherichia coli., Results: Simulation studies showed that sequential use of tetracycline and ampicillin reduced the level of double resistance, when compared to the combination treatment. The effect of the cycling frequency (how frequently antibiotics are alternated in a sequential treatment) of the two drugs was dependent upon the order in which the two drugs were used., Conclusion: Sequential treatment was more effective in preventing the growth of resistant strains when compared to the combination treatment. The cycling frequency did not play a role in suppressing the growth of resistant strains, but the specific order of the two antimicrobials did. Predictions made from the study could be used to redesign multidrug treatment strategies not only for intramuscular treatment in pigs, but also for other dosing routes.

We found a 6.1% bacterial contamination rate among 198 propofol vials collected after clinical use in 12 operating rooms of a high-complexity hospital in Cali, Colombia. Some propofol vials were used for extended periods (up to 72 hours), and only 26.1% of vials were punctured once. Median time of use, although not statistically significant, was higher in positive samples (7.2 vs 3.5 hours, P = .08). Education on the topic should stress that vials are single-patient use and must be immediately discarded after use., (Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the role played by adenoids as a reservoir for infection in children assigned for adenoidectomy., Methodology: The study included 35 children with adenoid hypertrophy. All patients underwent clinical examination and adenoidectomy, adenotonsillectomy, or myringotomy with insertion of aeration tube according to indications. Surgical specimens were processed for conventional bacterial culture examination and to assay for biofilm formation. The obtained adherence values using spectrophotometer at 595 nm (OD595) was used to classify isolates according to its biofilm forming capacity., Results: We did adenotonsillectomy and myringotomy with insertion of aeration tube in 5 patients having adenotonsillitis with otitis media with effusion. We did adenotonsillectomy in 12 patients having adenotonsillitis and adenoidectomy in 18 patients having adenoid hypertrophy. Thirty-one surgical specimens showed bacterial growth on conventional media, while 4 specimens failed to give growth. The predominant organism was H influenzae then Staph aureus and Strept pneumoniae. Thirty-two specimens showed biofilm forming capacity (BFC) of variable extent, while others showed no BFC., Conclusion: Adenoids act as a bacterial reservoir secondary to bacterial biofilm formation so could induce chronicity and initiate development of complications. Determination of BFC using the proposed protocol is feasible, inexpensive, and available and spares the need for sophisticated instruments or approaches., (© The Author(s) 2015.)

Clinical diagnostics in routine microbiology still mostly relies on bacterial growth, a time-consuming process that prevents test results to be used directly as key decision-making elements for therapeutic decisions. There is some evidence that Raman micro-spectroscopy provides clinically relevant information from a limited amount of bacterial cells, thus holding the promise of reduced growth times and accelerated result delivery. Indeed, bacterial identification at the species level directly from micro-colonies at an early time of growth (6h) directly on their growth medium has been demonstrated. However, such analysis is suspected to be partly destructive and could prevent the further growth of the colony needed for other tests, e.g. antibiotic susceptibility testing (AST). In the present study, we evaluated the effect of the powerful laser excitation used for Raman identification on micro-colonies probed after very short growth times. We show here, using envelope integrity markers (Syto 9 and Propidium Iodide) directly on ultra-small micro-colonies of a few tens of Escherichia coli and Staphylococcus epidermidis cells (3h growth time), that only the cells that are directly impacted by the laser lose their membrane integrity. Growth kinetics experiments show that the non-probed surrounding cells are sometimes also affected but that the micro-colonies keep their ability to grow, resulting in normal aspect and size of colonies after 15h of growth. Thus, Raman spectroscopy could be used for very early (<3h) identification of grown micro-organisms without impairing further antibiotics susceptibility characterization steps., (Copyright © 2014 Elsevier B.V. All rights reserved.)

For the last century, in vitro diagnostic process in microbiology has mainly relied on the growth of bacteria on the surface of a solid agar medium. Nevertheless, few studies focused in the past on the dynamics of microcolonies growth on agar surface before 8 to 10h of incubation. In this article, chromatic confocal microscopy has been applied to characterize the early development of a bacterial colony. This technology relies on a differential focusing depth of the white light. It allows one to fully measure the tridimensional shape of microcolonies more quickly than classical confocal microscopy but with the same spatial resolution. Placing the device in an incubator, the method was able to individually track colonies growing on an agar plate, and to follow the evolution of their surface or volume. Using an appropriate statistical modeling framework, for a given microorganism, the doubling time has been estimated for each individual colony, as well as its variability between colonies, both within and between agar plates. A proof of concept led on four bacterial strains of four distinct species demonstrated the feasibility and the interest of the approach. It showed in particular that doubling times derived from early tri-dimensional measurements on microcolonies differed from classical measurements in micro-dilutions based on optical diffusion. Such a precise characterization of the tri-dimensional shape of microcolonies in their late-lag to early-exponential phase could be beneficial in terms of in vitro diagnostics. Indeed, real-time monitoring of the biomass available in a colony could allow to run well established microbial identification workflows like, for instance, MALDI-TOF mass-spectrometry, as soon as a sufficient quantity of material is available, thereby reducing the time needed to provide a diagnostic. Moreover, as done for pre-identification of macro-colonies, morphological indicators such as three-dimensional growth profiles derived from microcolonies could be used to perform a first pre-identification step, but in a shorten time., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background Aims: Platelet-rich plasma (PRP), a blood derivative rich in platelets, is a relatively new technique used in tissue regeneration and engineering. The increased quantity of platelets makes this formulation of considerable value for their role in tissue healing and microbicidal activity. This activity was investigated against five of the most important strains involved in nosocomial infections (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Streptococcus faecalis) to understand the prophylactic role of pure (P)-PRP. Microbicidal proteins released from activated P-PRP platelets were also determined., Methods: The microbicidal activity of P-PRP and platelet-poor plasma (PPP) was evaluated on different concentrations of the five bacterial strains incubated for 1, 2, 4 and 18 h and plated on agar for 18-24 h. P-PRP and PPP-released microbicidal proteins were evaluated by means of multiplex bead-based immunoassays., Results: P-PRP and PPP inhibited bacterial growth for up to 2 h of incubation. The effect of P-PRP was significantly higher than that of PPP, mainly at the low seeding concentrations and/or shorter incubation times, depending on the bacterial strain. Chemokine (C-C motif) ligand-3, chemokine (C-C motif) ligand-5 and chemokine (C-X-C motif) ligand-1 were the molecules mostly related to Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus faecalis inhibition. Escherichia coli and Klebsiella pneumoniae were less influenced., Conclusions: The present results show that P-PRP might supply an early protection against bacterial contaminations during surgical interventions because the inhibitory activity is already evident from the first hour of treatment, which suggests that physiological molecules supplied in loco might be important in the time frame needed for the activation of the innate immune response., (Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Centrate, a type of nutrient-rich municipal wastewater was used to determine the effect of wastewater-borne bacteria on algal growth and nutrients removal efficiency in this study. The characteristics of algal and bacterial growth profiles, wastewater nutrient removal and effect of initial algal inoculums were systematically examined. The results showed that initial algal concentration had apparent effect on bacterial growth, and the presence of bacteria had a significant influence on algal growth pattern, suggesting symbiotic relationship between algae and bacteria at the initial stage of algae cultivation. The maximum algal biomass of 2.01 g/L with 0.1g/L initial algal inoculums concentration can be obtained during algae cultivation in raw centrate medium. The synergistic effect of centrate-borne bacteria and microalgae on algae growth and nutrient removal performance at initial fast growth stage has great potential to be applied to pilot-scale wastewater-based algae wastewater system cultivated in continuous or semi-continuous mode., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background and Objectives: Contamination risks of propofol 2%, remifentanil, and pantoprazole; and in vitro effects of these drugs on the growth of common infective agents in intensive care units were evaluated., Methods: For detection of contamination risk, drugs were prepared ready to use under intensive care unit conditions, were tested. Effects of these three drugs on bacterial growth were also investigated. Drugs were prepared at the concentrations used in the intensive care unit and inoculated with common pathogens after which they were incubated at 4°C, 22°C and 36°C. Subcultures were made at 0, 2, 4 and 8h and colony counts were evaluated. Minimum inhibitory concentration values were determined for all drugs at 4°C, 22°C and 36°C., Results: No growth was observed in the drugs prepared in the intensive care unit. Propofol tended to support while remifentanil inhibited bacterial growth. Effect of pantoprozole differed according to the bacteria tested. None of the drugs showed antibacterial activity at the maximum concentrations which may be achieved in blood of the patients., Conclusion: Propofol strongly supports the growth of the microorganisms tested, although remifentanil and pantoprazole do not. Therefore, it is important to follow the strict aseptic techniques for the preparation of propofol., (Copyright © 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.)

Background: Lysosomal storage diseases (LSDs), a group of inborn errors of metabolism, include various subtypes, for example, mucopolysaccharidosis (MPS) and Gaucher disease (GD). Besides the physical/mental disabilities, they suffer from several oral deteriorations. Aim: To evaluate the oral health status of Egyptian children with LSD. Design: Thirty LSD children and thirty non‐LSD children were enrolled for this study according to the inclusion and exclusion criteria. Dental indices were used to assess caries prevalence and periodontal status. Saliva samples were collected from all enrolled children to estimate interleukin 6 (IL‐6), tumor necrosis factor‐α (TNF‐α), and protein levels as well as Streptococcus mutans and Lactobacilli colony counts. Results: Children with MPS and GD showed non‐significant differences in decayed, missing, or filled teeth (DMFT) scores (p =.115). Scores of dmft showed a significant increase in MPS, but not in GD children (p =.020, p =.127). Children with LSD showed significantly increased Modified Gingival Index (MGI), Plaque Index (PI), Oral Hygiene Index (OHI‐s) scores (p <.001) and salivary IL‐6 and TNF‐α (p =.007, p =.001, p <.0001, p =.002, respectively) and salivary total proteins (p =.001) levels. Unexpectedly, non‐significant differences were observed in salivary Streptococcus mutans or Lactobacilli counts in children with MPS and GD (p =.058, p =.420, p =.502, p =.053, respectively). Conclusion: To our knowledge, this is the first article that evaluates Egyptian children with LSD. We demonstrated high caries prevalence in primary teeth, not permanent teeth, in children with MPS and poor gingival/hygiene status in children with MPS and GD, which triggered a state of inflammation. The daily supplement intake prevented oral bacterial growth. The most probable cause of oral alterations is decreased salivary flow rate, as deduced from a significantly increased salivary protein. [ABSTRACT FROM AUTHOR]

Background: Microorganisms in dental unit water (DUW) play a significant role in dental bioaerosols. If the methods used to decontaminate DUW also help improve air quality in dental clinics is worth exploring. In this study, we aim to identify the source of bacteria in dental bioaerosols and investigate the impact of waterline disinfectants on the quantity and composition of bacteria in DUW and bioaerosols. Methods: Two dental chair units in a separate treatment room are installed with two different waterline decontamination systems, a plasma or iodine cartridge. The experiment was performed in two phases, before and after installing the decontamination systems. Aerosol is generated via running airotor in the subject's mouth. Before and after the procedure, the air samples were collected with an active air sampling machine onto agar plate and filter paper for genomic DNA extraction. The subject's saliva and DUW samples were also collected. The samples were analyzed further with bacterial counting and metataxonomics analysis. Results: The bacteria present in the air sample after the aerosol-generating procedure were confirmed to be derived from the air-before, saliva, and DUW in 51.43%, 6.38%, and 18.60%, respectively. The saliva samples demonstrated the highest alpha diversity (within the sample), whereas the air samples had the least. Both waterline disinfectants effectively controlled bacteria in DUW but did not affect the bacterial number and composition in the air. Conclusions: Dental bioaerosols are composed of bacteria from saliva and DUW. Plasma and iodine showed a trend in controlling bacterial contamination in DUW but did not alter the bacterial count and composition in dental bioaerosols. [ABSTRACT FROM AUTHOR]

In nature, organisms experience combinations of stressors. However, laboratory studies use batch cultures, which simplify reality and focus on population-level responses to individual stressors. 1,2,3,4,5 In recent years, bacterial stress responses have been examined with single-cell resolution using microfluidics. 6,7,8,9,10,11,12 Here, we use a microfluidic approach to simultaneously provide a physical stressor (shear flow) and a chemical stressor (H 2 O 2) to the human pathogen Pseudomonas aeruginosa. By treating cells with levels of flow and H 2 O 2 that commonly co-occur in human host tissues, 13,14,15,16,17,18 we discover that previous reports significantly overestimate the H 2 O 2 levels required to block bacterial growth. Specifically, we establish that flow increases H 2 O 2 effectiveness 50-fold, explaining why previous studies lacking flow required much higher concentrations. Using natural H 2 O 2 levels, we identify the core H 2 O 2 regulon, characterize OxyR-mediated dynamic regulation, and demonstrate that multiple H 2 O 2 scavenging systems have redundant roles. By examining single-cell behavior, we serendipitously discover that the combined effects of H 2 O 2 and flow block pilus-driven surface migration. Thus, our results counter previous studies and reveal that natural levels of H 2 O 2 and flow synergize to restrict bacterial motility and survival. By studying two stressors at once, our research highlights the limitations of oversimplifying nature and demonstrates that physical and chemical stress can combine to yield unpredictable effects. [Display omitted] • Shear flow and H 2 O 2 combine to block bacterial migration and growth • Natural levels of H 2 O 2 trigger a small, clearly defined regulon • Shear flow enhances H 2 O 2 effectiveness by replenishing H 2 O 2 Here, Sharma et al. use microfluidics to simultaneously provide a physical stressor (shear flow) and a chemical stressor (H 2 O 2) to the human pathogen Pseudomonas aeruginosa. The replenishing power of shear flow increases H 2 O 2 effectiveness 50-fold, allowing natural levels of H 2 O 2 to block bacterial migration and growth. [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]

Wound healing is a series of complex and dynamic processes which occur in several stages. Optimal wound healing is essential for restoring the integrity and function of the affected area. Although medicated wound dressings have been extensively employed to control wound infection, the risks associated with antimicrobials make the use of non-medicated alternatives necessary. Nevertheless, the relationship between the concentrations of medicated wound dressings and their antimicrobial activities, along with their wound healing efficacies, still remains unclear. Non-medicated wound dressings are an alternative to dressings that contain active ingredients acting as antimicrobials or antiseptics. In the present study, the researchers examined the reduction of bacterial load as the primary endpoint and the healing rate as the secondary endpoint, comparing microporous ceramic dressings to silver-impregnated dressings in participants from two outpatient wound management clinics. The study included 25 participants in the silver-impregnated dressing (control) group and 28 participants in the ceramic dressing (study) group. The participants' wounds were assessed through MolecuLight i:X (MolecuLight Inc., Canada) wound tracing and MolecuLight i:X fluorescence imaging to measure the wound size, as well as presence of a bacterial load of >104 colony forming units/g at weeks 1, 2, 3 and 4. The results indicated that there was a significant difference in the distribution over the categories of bacterial load cleared after weeks 1, 2, 3 or 4 in the two groups. Moreover, the bacterial load cleared significantly faster in the study group (p=0.001). Mean wound size was 10.93cm2 (range: 0.10–37.95cm2) in the control group and 11.48cm2 (range: 0.80–60cm2) in the study group. In the maximum likelihood regression analysis, the mean reduction in wound area for the study group was greater than that for the control group. The study concluded that the ceramic dressings could be an effective alternative to silver-impregnated dressings when treating infected wounds. [ABSTRACT FROM AUTHOR]

E. coli and total coliforms are the most widely used indicator organisms for microbial monitoring of drinking water and recreational freshwater. In many remote and low-resource settings, however, conventional laboratory methods for quantifying these indicators are challenging or infeasible to perform due to limited access to laboratory facilities. The availability of rapid, low-cost methods for quantifying indicator organisms in freshwater samples without the need for laboratory facilities is crucial to facilitate the rapid and robust monitoring of microbial water quality in these types of settings. The global misuse and abuse of antimicrobials have contributed to the rise of antimicrobial resistance. Thus, simple culture methods are needed to detect indicators of such bacteria in freshwaters. In 2021, the World Health Organization released the Tricycle protocol to address this issue by providing guidance for culture-based detection of extended-spectrum beta-lactamase (ESBL)-producing E. coli in environmental samples. Our research goal was to compare the 100-ml sample volume ESBL E. coli quantal and enumerative commercial tests against the more complex Tricycle protocol to detect and quantify ESBL E. coli in surface waters. Both commercial tests gave results comparable with the results obtained using the Tricycle protocol, and the quantal and enumerative commercial tests were easier and faster to perform than the Tricycle protocol. [ABSTRACT FROM AUTHOR]

The study addressed the antimicrobial potential of coconut oil, both extra virgin and homemade, against oral bacteria. For this evaluation, chlorhexidine was used as a comparison standard. The tests were conducted in five culture media, one for chlorhexidine, another for extra virgin coconut oil, and a third for homemade coconut oil. The results revealed that extra virgin coconut oil exhibited partial inhibition of bacterial growth, being effective only against certain strains, while homemade coconut oil showed no considerable effectiveness in any test. On the other hand, chlorhexidine displayed the expected and excellent antimicrobial action. These results highlight the need for further studies on extra virgin coconut oil, especially to better understand the bacteria it inhibits, in order to promote a more effective use of this compound. [ABSTRACT FROM AUTHOR]

To investigate the hypothesis of top-down control by viruses and heterotrophic nanoflagellates on bacterial-mediated carbon fluxes in freshwater systems, a year-long study (2023–2024) was conducted in the pelagic zone of Lake Saint-Gervais (France). The variability in BGE (9.9% to 45.5%) was attributed to the decoupling of production and respiration, providing bacterioplankton communities with a competitive advantage in adapting to fluctuating environmental disturbances in freshwater systems. The high nucleic acid (HNA) bacterial community, the active fraction, contributed the most to bacterial production and was linked to BGE estimates. Weak bottom-up controls (nutrient concentrations and stoichiometry) on BGE suggested a stronger role for mortality forces. Among viral subgroups (VLP1–VLP4) identified via flow cytometry, the dominant low-fluorescence DNA VLP1 subgroup (range = 0.7 to 3.1 × 108 VLP mL−1) accounting for the majority of viral production was closely linked to the HNA population. Both top-down forces exerted antagonistic effects on BGE at the community level. The preferential lysis and grazing of the susceptible HNA population, which stimulated bacterial community respiration more than production in the non-target population, resulted in reduced BGE. These results underscore the key role of top-down processes in shaping carbon flux through bacterioplankton in this freshwater system. [ABSTRACT FROM AUTHOR]

Objective: In this pilot study, we verified safe practices for breast milk expression, storage, and duration, based on bacteriological results. Results: We collected breast milk samples from three healthy lactating volunteers and analyzed the bacterial flora and changes in the viable bacterial counts (including those of Staphylococcus) of the samples. Although no consistent change could be observed in the abundance of a particular bacterial group in samples expressed under hygienic control conditions, viable bacterial counts were higher in self-expressed milk than in milk expressed under hygienic control conditions. In conclusion, increased hygiene awareness is vital during breast milk expression and storage. [ABSTRACT FROM AUTHOR]

Bacterial biofilms are organized heterogeneous assemblages of microbial cells encased within a self-produced matrix of exopolysaccharides, extracellular DNA and proteins. Over the last decade, more and more biofilm-associated proteins have been discovered and investigated. Furthermore, omics techniques such as transcriptomes, proteomes also play important roles in identifying new biofilmassociated genes or proteins. However, those important data have been uploaded separately to various databases, which creates obstacles for biofilm researchers to have a comprehensive access to these data. In this work, we constructed BBSdb, a state-of-the-art open resource of bacterial biofilmassociated protein. It includes 48 different bacteria species, 105 transcriptome datasets, 21 proteome datasets, 1205 experimental samples, 57,823 differentially expressed genes (DEGs), 13,605 differentially expressed proteins (DEPs), 1,930 'Top 5% differentially expressed genes', 444 'Threshold-based DEGs' and a predictor for prediction of biofilm-associated protein. In addition, 1,781 biofilm-associated proteins, including annotation and sequences, were extracted from 942 articles and public databases via text-mining analysis. We used E. coli as an example to represent how to explore potential biofilmassociated proteins in bacteria. We believe that this study will be of broad interest to researchers in field of bacteria, especially biofilms, which are involved in bacterial growth, pathogenicity, and drug resistance. [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]

The article evaluates the impact of submerged culture parameters on growth and naringinase activity of Bacillus amyloliquefaciens D1 isolated from citrus gardens of North-East India. The study describes the morphological, biochemical and molecular characteristics of bacterial isolates, profiling of fatty acids, 16S rRNA gene analysis and homology. It examines the effects of incubation period, potential of hydrogen, temperature, carbon and nitrogen sources on growth and naringinase activity.

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Habbatussauda or black cumin, Nigella sativa, is an herbal ingredient used for by community as medicine. It contains tannins, thymoquinone, thymol, pinene, and p-cymene that inhibit the bacterial growth of both positive and negative grams. Streptococcus mutans is a primary bacterium that makes caries on teeth since it has a glucosyltransferase enzyme, or GFT. This enzyme could catalyse glucan synthesis in the process of tooth caries. This study determines the influence of the mouthwash with black cumin extract, Nigella sativa, in inhibiting the bacterial growth of Streptococcus mutans within the in vitro situation. This laboratory experimental research applied a post-test-only control group design. The applied bacterial activity test was well diffusion. The researchers grouped the samples into six treatment samples: the mouthwash solution with concentrations of 3%, 6%, 9%, and 12%; and the negative and positive control groups. The positive control group used mouthwash with 0.2% chlorhexidine. Each group consisted of four samples. Thus, the total samples were 24. The test of the bacterial growth inhibiting power applied the well technique. The results of this study revealed that the extracted black cumin mouthwash solution with concentrations of 3%, 6%, 9%, and 12% influenced the Streptococcus Mutans bacterial growth inhibition. The ANOVA test result obtained a significant value or (p) less than 0.005, p < 0.05. The Post Hoc LSD test found the differences among the groups with the inter-group significance of p < 0.05. The usage of the extracted black cumin mouthwash, Nigella sativa, influenced the inhibiting zone of the Streptococcus mutans bacterial growth in an in vitro manner. The mouthwash with 9% black cumin has the highest effect to inhibit the Streptococcus mutans bacterial growth. [ABSTRACT FROM AUTHOR]