Microbial Tolerance Research Articles

Antimicrobial Biomaterials Based on Physical and Physicochemical Action

AbstractDeveloping effective antimicrobial biomaterials is a relevant and fast‐growing field in advanced healthcare materials. Several well‐known (e.g., traditional antibiotics, silver, copper etc.) and newer (e.g., nanostructured, chemical, biomimetic etc.) approaches have been researched and developed in recent years and valuable knowledge has been gained. However, biomaterials associated infections (BAIs) remain a largely unsolved problem and breakthroughs in this area are sparse. Hence, novel high risk and potential high gain approaches are needed to address the important challenge of BAIs. Antibiotic free antimicrobial biomaterials that are largely based on physical action are promising, since they reduce the risk of antibiotic resistance and tolerance. Here, selected examples are reviewed such antimicrobial biomaterials, namely switchable, protein‐based, carbon‐based and bioactive glass, considering microbiological aspects of BAIs. The review shows that antimicrobial biomaterials mainly based on physical action are powerful tools to control microbial growth at biomaterials interfaces. These biomaterials have major clinical and application potential for future antimicrobial healthcare materials without promoting microbial tolerance. It also shows that the antimicrobial action of these materials is based on different complex processes and mechanisms, often on the nanoscale. The review concludes with an outlook and highlights current important research questions in antimicrobial biomaterials.

The effect of inoculum source of different pollution levels on the performances of microbial fuel cell biosensors

Selection of inoculum sources is a key factor in constructing microbial fuel cells (MFCs), and the property of inoculum sources is greatly affected by the degree of environmental pollution. However, limited attention has been paid to how these differences affect the response of MFC biosensors. Here the effects of inoculum sources with varying pollution levels on the performances of constructed MFCs were evaluated, and the microbial communities were analyzed before and after inoculation. The results showed significant differences in the detection of biochemical oxygen demand (BOD) and toxicity (Cu2+) among the five groups of MFC biosensors. Combined with the data of the microbial community, the results indicated that the increase rate of the initial start-up voltage is related to the abundance of original electroactive bacteria (EAB) in the inoculum source. The higher the abundance of EAB, the faster increase rate in the initial start-up voltage and the shorter start-up time. The difference in the detection range of the BOD should be related to the ability of the microbial communities to withstand the organic shock loads. The microbial community's tolerance to Cu2+ was affected by the original water quality of the inoculum source. The high metal ion content leads to low sensitivity of MFC biosensor to Cu2+ ion. Enterobacteriaceae were abundant in all the five groups of MFCs, indicating that the dominant bacteria can be enriched in MFC anode biofilms with the inoculum sources of different pollution levels. The microbial community compositions of the anode biofilms were affected by the inoculum sources of different pollution levels, which in turn resulted in the differences in MFCs performances.

Microplastics and benthic animals reshape the geochemical characteristics of dissolved organic matter by inducing changes in keystone microbes in riparian sediments

Dissolved organic matter (DOM) in riparian sediments plays a vital role in regulating element cycling and pollutant behavior of river ecosystems. Microplastics (MPs) and benthic animals (BAs) have been frequently detected in riparian sediments, influencing the substance transformation in river ecosystems. However, there is still a lack of systematic investigation on the effects of MPs and BAs on sediment DOM. This study investigated the impact of MPs and BAs on the geochemical characteristics of DOM in riparian sediments and their microbial mechanisms. The results showed that MPs and BAs increased sediment DOC concentration by 34.24%∼232.97% and promoted the conversion of macromolecular components to small molecular components, thereby reducing the humification degree of DOM. Mathematical model verified that the changes of keystone microbes composition in sediments were direct factors affecting the characteristics of DOM in riparian sediment. Especially, MPs tolerant microbes, including Planctomicrobium, Rhodobacter, Hirschia and Lautropia, significantly increased DOC concentration and decreased humification degree (P < 0.05). In addition, MPs and BAs could also influence keystone microbes in sediments by altering the structure of microbial network, thereby indirectly affecting DOM characteristics. The study demonstrates the pollution behavior of MPs in river ecosystems and provides a basis for protecting the ecological function of riparian sediments from MPs pollution.

Seasonal response of soil microbial community structure and life history strategies to winter snow cover change in a temperate forest

Snow cover provides a thermally stable and humid soil environment and thereby regulates soil microbial communities and biogeochemical cycling. A warmer world with large reductions in snow cover and earlier spring snowmelt may disrupt this stability and associated ecosystem functioning. Yet, little is known about the response of soil microbial communities to decreased snowpack and potential carry-over effects beyond the snow cover period. Herein, we tested this response by conducting a snowpack manipulation experiment (control, addition, and removal) in a temperate forest. Our results showed that fungi were more sensitive to changes in snowpack. Thicker snowpack increased the diversity of fungi, but had weak effects on the diversity of bacteria in winter. Thickening snow cover promoted the ratio of fungi to bacteria abundance across the year, and such relative increase in fungi abundance was largely driven by Basidiomycota phyla (Agaricomycetes class). Increased snowpack decreased soil nitrate concentration, and produced carry-over biogeochemical effects evidenced by increased summer β-1,4-glucosidase and N-acetyl-β-glucosaminidase activities. On a seasonal scale, microbial biomass peaked at both winter and summer; winter microbial community was fungi dominated, while bacteria dominated in summer. The abundances of bacterial phyla had greater seasonal variation than fungal phyla. Specifically, Actinobacteria had greater dominance in winter than in summer, while Acidobacteria, Proteobacteria, and Verrucomicrobia had greater abundance in summer than in winter. Microbial high yield-resource acquisition-stress tolerance life history strategies showed significant seasonal tradeoffs, i.e., resource acquisition and stress tolerance strategies dominated in summer, while high yield strategy dominated in winter. Overall, our findings underline that climate-induced reductions in snow cover can disrupt soil biogeochemical cycling also beyond the snow cover period due to shifts in soil microbial community structure and life history strategies.

A mechanistic modelling approach of the host-microbiota interactions to investigate beneficial symbiotic resilience in the human gut.

The health and well-being of a host are deeply influenced by the interactions with its gut microbiota. Contrasted environmental conditions, such as diseases or dietary habits, play a pivotal role in modulating these interactions, impacting microbiota composition and functionality. Such conditions can also lead to transitions from beneficial to detrimental symbiosis, viewed as alternative stable states of the host-microbiota dialogue. This article introduces a novel mathematical model exploring host-microbiota interactions, integrating dynamics of the colonic epithelial crypt, microbial metabolic functions, inflammation sensitivity and colon flows in a transverse section. The model considers metabolic shifts in epithelial cells based on butyrate and hydrogen sulfide concentrations, innate immune pattern recognition receptor activation, microbial oxygen tolerance and the impact of antimicrobial peptides on the microbiota. Using the model, we demonstrated that a high-protein, low-fibre diet exacerbates detrimental interactions and compromises beneficial symbiotic resilience, underscoring a destabilizing effect towards an unhealthy state. Moreover, the proposed model provides essential insights into oxygen levels, fibre and protein breakdown, and basic mechanisms of innate immunity in the colon and offers a crucial understanding of factors influencing the colon environment.

Salt Tolerant Microbes (Active Metabolites) Mediated Nanoparticle: Drug Delivery and Future Prospects

Salt Tolerant Microbes are a group of microorganisms that grow, develop, and survive in extremely high salt concentrations. Based on their tolerance level they generally grow up optimally at pH values beyond 9.0, but the growth is inhibited at the pH value that is most closely associated with neutral 6.5. They have minimal dietary needs and a good salt quantity that is high enough to osmotic pressure. They can produce biological metabolites that have certain actions such as antibacterial, antifungal, antioxidant, and anticancer. We discussed in this article various pharmaceutical formulations of salt-tolerant microbes, every formulation shows the specific pharmacological actions like anti-cancer activity, anti-oxidant activity, and anti-microbial activity, and also discusses methods for the biosynthesis of salt-tolerant microbes’ nanoparticles.

Response of Microbial Communities to Naturally Occurring Radioactive Material-Contaminated Sediments: A Microcosm-Based Study.

There is a growing need to understand the potential ecological impacts of contaminants in offshore oil and gas infrastructure, especially if that infrastructure is to be left in situ as a decommissioning option. Naturally occurring radioactive material (NORM) is one type of contaminant found in solid deposits on internal surfaces of infrastructure that poses potential ecological harm if released into the marine environment. Microbes are important components of marine sediment ecosystems because they provide ecosystem services, yet the impacts of NORM contamination to these communities are not well understood. The present study aimed to investigate the response of benthic microbial communities to NORM-contaminated scale, collected from an offshore oil and gas system, via controlled laboratory microcosm studies. Changes to microbial communities in natural sediment and sediments spiked with NORM at radium-226 activity concentrations ranging from 9.5 to 59.8 Bq/kg (in partial equilibria with progeny) over 7 and 28 days were investigated using high-throughput sequencing of environmental DNA extracted from experimental sediments. There were no significant differences in microbial community composition between control and scale-spiked sediments over 7 and 28 days. However, we observed a greater presence of Firmicutes in the scale-mixed treatment and Chloroflexi in the scale-surface treatments after 28 days. This could suggest selection for species with contaminant tolerance or potential resilience to radiation and metal toxicity. Further research is needed to explore microbial tolerance mechanisms and their potential as indicators of effects of radionuclide-contaminated sediments. The present study demonstrated that microcosm studies can provide valuable insights about the potential impacts of contamination from oil and gas infrastructure to sediment microbial communities. Environ Toxicol Chem 2024;43:1648-1661. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

In vitro generation of genetic diversity for directed evolution by error-prone artificial DNA synthesis

Generating genetic diversity lies at the heart of directed evolution which has been widely used to engineer genetic parts and gene circuits in synthetic biology. With the ever-expanding application of directed evolution, different approaches of generating genetic diversity are required to enrich the traditional toolbox. Here we show in vitro generation of genetic diversity for directed evolution by error-prone artificial DNA synthesis (epADS). This approach comprises a three-step process which incorporates base errors randomly generated during chemical synthesis of oligonucleotides under specific conditions into the target DNA. Through this method, 200 ~ 4000 folds of diversification in fluorescent strength have been achieved in genes encoding fluorescent proteins. EpADS has also been successfully used to diversify regulatory genetic parts, synthetic gene circuits and even increase microbial tolerance to carbenicillin in a short time period. EpADS would be an alternative tool for directed evolution which may have useful applications in synthetic biology.

Mining novel gene targets for improving tolerance to furfural and acetic acid in Yarrowia lipolytica using whole-genome CRISPRi library

Abundant renewable resource lignocellulosic biomass possesses tremendous potential for green biomanufacturing, while its efficient utilization by Yarrowia lipolytica, an attractive biochemical production host, is restricted since the presence of inhibitors furfural and acetic acid in lignocellulosic hydrolysate. Given deficient understanding of inherent interactions between inhibitors and cellular metabolism, sufficiently mining relevant genes is necessary. Herein, 14 novel gene targets were discovered using clustered regularly interspaced short palindromic repeats interference library in Y. lipolytica, achieving tolerance to 0.35 % (v/v) acetic acid (the highest concentration reported in Y. lipolytica), 4.8 mM furfural, or a combination of 2.4 mM furfural and 0.15 % (v/v) acetic acid. The tolerance mechanism might involve improvement of cell division and decrease of reactive oxygen species level. Transcriptional repression of effective gene targets still enabled tolerance when xylose was a carbon source. This work forms a robust foundation for improving microbial tolerance to lignocellulose-derived inhibitors and revealing underlying mechanism.

Towards zero excess sludge discharge with built-in ozonation for wastewater biological treatment

In this study, a biological treatment process, which used a built-in ozonation bypass to achieve sludge reduction, was built to treat the industrial antifreeze production wastewater (mainly composed of ethylene glycol). The results indicated there is a positive correlation between ozone dosage and sludge reduction. At the laboratory level, the MLSS in the system can be stably controlled at around 3400 mg MLSS L−1 under the dosage of 0.18 g O3 g−1 MLSS. Ozonation can increase the compactness of sludge flocs (fractal dimension increased from 1.89 to 1.92). Ozone destroys microbial cell membranes and alters the structure of sludge flocs through direct oxidation through electrophilic reactions. It leads to the release of intracellular polysaccharides, proteins, and other biological macromolecules in microorganisms, thereby promoting the implicit growth of microbial populations. Some bacteria such as g_Pseudomonas, g_Gemmobacter, etc. have strong ethylene glycol degradation ability and tolerance to ozonation. The removal of ethylene glycol includes the glyoxylate cycle, glycine serine carbon cycle, and the glutamate-cysteine ligase pathway of assimilation. Gene KatG and gpx may be key factors in improving microbial tolerance to ozonation. The comprehensive evaluation from the perspectives of cost and carbon emission shows that choosing ozone cracking-implicit growth in wastewater treatment systems has significant cost advantages and application value.

Longitudinal profiling of the intestinal microbiome in children with cystic fibrosis treated with elexacaftor-tezacaftor-ivacaftor.

The intestinal microbiome influences growth and disease progression in children with cystic fibrosis (CF). Elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA), the newest pharmaceutical modulator for CF, restores the function of the pathogenic mutated CF transmembrane conductance regulator (CFTR) channel. We performed a single-center longitudinal analysis of the effect of ELX/TEZ/IVA on the intestinal microbiome, intestinal inflammation, and clinical parameters in children with CF. Following ELX/TEZ/IVA, children with CF had significant improvements in body mass index and percent predicted forced expiratory volume in one second, and required fewer antibiotics for respiratory infections. Intestinal microbiome diversity increased following ELX/TEZ/IVA coupled with a decrease in the intestinal carriage of Staphylococcus aureus, the predominant respiratory pathogen in children with CF. There was a reduced abundance of microbiome-encoded antibiotic resistance genes. Microbial pathways for aerobic respiration were reduced after ELX/TEZ/IVA. The abundance of microbial acid tolerance genes was reduced, indicating microbial adaptation to increased CFTR function. In all, this study represents the first comprehensive analysis of the intestinal microbiome in children with CF receiving ELX/TEZ/IVA.IMPORTANCECystic fibrosis (CF) is an autosomal recessive disease with significant gastrointestinal symptoms in addition to pulmonary complications. Recently approved treatments for CF, CF transmembrane conductance regulator (CFTR) modulators, are anticipated to substantially improve the care of people with CF and extend their lifespans. Prior work has shown that the intestinal microbiome correlates with health outcomes in CF, particularly in children. Here, we study the intestinal microbiome of children with CF before and after the CFTR modulator, ELX/TEZ/IVA. We identify promising improvements in microbiome diversity, reduced measures of intestinal inflammation, and reduced antibiotic resistance genes. We present specific bacterial taxa and protein groups which change following ELX/TEZ/IVA. These results will inform future mechanistic studies to understand the microbial improvements associated with CFTR modulator treatment. This study demonstrates how the microbiome can change in response to a targeted medication that corrects a genetic disease.

Ecological features of trace elements tolerant microbes isolated from sewage sludge of urban wastewater treatment plant

Worldwide wastewater treatment plants generate enormous amounts of sewage sludge, and their further disposal depends on the treatment technologies applied and spontaneously occurring microbiological processes. From different ages urban sewage sludge, 12 strains of bacteria with simultaneous tolerance to two or more trace elements: Co, Ni, Cu, Zn, Cd and Pb at concentration of 3-5 mmol were isolated and identified by PCR of target genes and Sanger sequencing methods. The isloated metal(loids) tolerant strains belong to the species, i.e., Serratia fonticola, Rhodococcus qingshengii, Pseudomonas fragi, Pseudomonas extremaustralis, Pseudomonas cedrina, Stenotrophomonas maltophilia, Serratia liquefaciens and Citrobacter freundii. The ecological features of the isolated strains were studied. The optimal growth temperatures for most strains was 15–30°C at pH range of 5–9, although some strains grew at 7°C (Pseudomonas fragi SS0-4, Serratia fonticola SS0-9 and Serratia fonticola SS12-11). Satisfactory growth of two strains (Serratia fonticola SS0-1and Citrobacter freundii SS60-12) was noted in an acidic medium at pH 4. Most of the strains grew in the NaCl concentration range of 1–5%. The isolated bacteria resistant to high concentrations of trace elements can be used for the effective mineralization of sewage sludge and for the decontamination of wastewater.

Competition of Cd(II) and Pb(II) on the bacterial cells: a new insight from bioaccumulation based on NanoSIMS imaging.

Polymetallic exposure causes complex toxicity to microorganisms. In this study, we investigated the responses of Escherichia coli under co-existence of cadmium (Cd) and lead (Pb), primarily based on biochemical analysis and RNA sequencing. Cd completely inhibited bacterial growth at a concentration of 2.41 mmol/L, with its removal rate as low as <10%. In contrast, the Pb removal rate was >95% under equimolar sole Pb stress. In addition, the Raman analysis confirmed the loss of proteins for the bacterial cells. Under the co-existence of Cd and Pb, the Cd toxicity to E. coli was alleviated. Meanwhile, the biosorption of Pb cations was more intense during the competitive sorption with Cd. Transmission electron microscopy images showed that a few cells were elongated during incubation, i.e., the average cellular length increased from 1.535 ± 0.407 to 1.845 ± 0.620 µm. Moreover, NanoSIMS imaging showed that the intracellular distribution of Cd and Pb was coupled with sulfur. Genes regulating sulfate transporter were also upregulated to promote sulfate assimilation. Then, the subsequent production of biogenic sulfide and sulfur-containing amino acids was enhanced. Although this strategy based on S enrichment could resist the polymetallic stress, not all related genes were induced to upregulate under sole Cd stress. Therefore, the S metabolism might remodel the microbial resistance to variable occurrence of heavy metals. Furthermore, the competitive sorption (in contrast to sole Cd stress) could prevent microbial cells from strong Cd toxicity.IMPORTANCEMicrobial tolerance and resistance to heavy metals have been widely studied under stress of single metals. However, the polymetallic exposure seems to prevail in the environment. Though microbial resistance can alleviate the effects of exogenous stress, the taxonomic or functional response to polymetallic exposure is still not fully understood. We determined the strong cytotoxicity of cadmium (Cd) on growth, and cell elongation would be driven by Cd stress. The addition of appropriate lead (Pb) showed a stimulating effect on microbial bioactivity. Meanwhile, the biosorption of Pb was more intense during co-existence of Pb and Cd. Our work also revealed the spatial coupling of intracellular S and Cd/Pb. In particular, the S assimilation was promoted by Pb stress. This work elucidated the microbial responses to polymetallic exposure and may provide new insights into the antagonistic function during metal stresses.

Biocidal Verification Program for Healthcare Facilities: Evaluation of the Efficacy and Microbial Tolerance of Disinfectants

Context: The disinfection of healthcare facilities is of utmost importance to prevent the spread of infectious diseases. In this regard, biocidal activity testing is used to evaluate the efficacy of disinfectants in hospitals. Aim: Establishing a disinfectant efficacy test aimed at combating infections and cross-contamination. Settings and Design: The experiment was carried out in two treatment groups for each of the four microorganisms on ten surface coupons, with a viability control group determined as the baseline inoculum. Methods and Materials: The study used two disinfectants—hydroxyethane (ethylene hydrate) and 2-hydroxypropane (sec-propyl alcohol)—to evaluate their efficacy in reducing bacterial contamination on inanimate surfaces. Statistical analysis used: The data obtained was analyzed using Minitab software, which involved a normal probability plot, a homogeneity of variances test, and a test for equal variances. The statistical significance level was set at α = 0.05. Results: The normal probability plot of microorganism-disinfectant groups with a 95% confidence interval showed improvement in normalization after the logarithmic transformation of datasets. The homogeneity of variances test did not reveal any statistically significant differences between the groups, and all the comparison intervals overlapped for the logarithmically transformed datasets in contrast to the raw datasets. The bacterial reduction after exposure to disinfectants for five minutes compared with the control group in the surface challenge biocidal test expressed as absolute and logarithmic reduction showed a significant reduction in bacterial growth, with Burkholderia cepacia showing greater persistence on the examined sample of the surfaces. Conclusions: The current study showed that the effect of the microorganism tolerance contributed to the variation in responses rather than the disinfectant or the surface types, suggesting the risk of resistant bacteria on the contaminated surface in the dissemination of infections. Thus, monitoring and routine disinfection validation programs for the control of microbial burden in healthcare are crucial for infection and contamination mitigation

Oxidation of Ammonia in Fish Ponds to Nitrates Using Free and Immobilized Nitrifying Bacteria

In fish farming, ammonia stands out as detrimental toxicant, with the potential to significantly impede growth and even lead to fish mortality. The adverse effects of ammonia exposure in aquatic environments primarily stem from elevated concentrations of unionized ammonium (NH3), which can readily permeate gill membranes. This study aimed at assessing the capability of free and mobilized forms of nitrifying bacteria in converting ammonia to nitrates. Nitrifying bacteria were isolated from water samples, resulting in the identification of two Pseudomonas species and two Bacillus species. The Bacillus sp., designated with the isolate code, B4 which exhibited the ability to convert ammonia to both nitrite and nitrate while demonstrating resilience to high ammonia concentrations. When Pseudomonas sp. (C4) and Bacillus sp. (B4) were utilized, the total ammonia concentration was reduced from 2 mg/L to 1.4 mg/L and 1.3 mg/L, respectively. Moreover, the immobilized forms of Pseudomonas sp. C4 and Bacillus sp. B4 achieved a more substantial reduction (75%), lowering the total ammonia concentration from 2 mg/L to 0.5 mg/L within 5-days period. Both nitrifying bacteria not only exhibited ammonia removal capabilities but also demonstrated their proficiency in transforming ammonia into nitrate. Immobilization proved effective in enhancing microbial tolerance to high ammonia concentrations, ultimately leading to improved water quality and the preservation of aquatic animal health.

Adaptive laboratory evolution and transcriptomics-guided engineering of Escherichia coli for increased isobutanol tolerance.

As a renewable energy from biomass, isobutanol is considered as a promising alternative to fossil fuels. To biotechnologically produce isobutanol, strain development using industrial microbial hosts, such as Escherichia coli, has been conducted by introducing a heterologous isobutanol synthetic pathway. However, the toxicity of produced isobutanol inhibits cell growth, thereby restricting improvements in isobutanol titer, yield, and productivity. Therefore, the development of robust microbial strains tolerant to isobutanol is required. In this study, isobutanol-tolerant mutants were isolated from two E. coli parental strains, E. coli BL21(DE3) and MG1655(DE3), through adaptive laboratory evolution (ALE) under high isobutanol concentrations. Subsequently, 16 putative genes responsible for isobutanol tolerance were identified by transcriptomic analysis. When overexpressed in E. coli, four genes (fadB, dppC, acs, and csiD) conferred isobutanol tolerance. A fermentation study with a reverse engineered isobutanol-producing E. coli JK209 strain showed that fadB or dppC overexpression improved isobutanol titers by 1.5 times, compared to the control strain. Through coupling adaptive evolution with transcriptomic analysis, new genetic targets utilizable were identified as the basis for the development of an isobutanol-tolerant strain. Thus, these new findings will be helpful not only for a fundamental understanding of microbial isobutanol tolerance but also for facilitating industrially feasible isobutanol production.

Escherichia coli displays a conserved membrane proteomic response to a range of alcohols

BackgroundAlcohol is a good and environment-friendly fuel that can be microbially produced, capable of eliminating many of the limitations of the present-day fossil fuels. However, the inherent toxic nature of alcohols to the microbial cells leads to end-product inhibition that limits large-scale alcohol production by fermentation. Fundamental knowledge about the stress responses of microorganisms to alcohols would greatly facilitate to improve the microbial alcohol tolerance. The current study elucidates and compares the changes in the membrane proteome of Escherichia coli in response to a range of alcohols.ResultsAlthough alcohol toxicity increased exponentially with alcohol chain length (2–6 carbon), similar stress responses were observed in the inner and outer membrane proteome of E. coli in the presence of 2-, 4- and 6-carbon alcohols at the MIC50. This pertains to: (1) increased levels of inner membrane transporters for uptake of energy-producing metabolites, (2) reduced levels of non-essential proteins, associated with anaerobic, carbon starvation and osmotic stress, for energy conservation, (3) increased levels of murein degrading enzymes (MltA, EmtA, MliC and DigH) promoting cell elongation and 4) reduced levels of most outer membrane β-barrel proteins (LptD, FadL, LamB, TolC and BamA). Major outer membrane β-barrel protein OmpC, which is known to contribute to ethanol tolerance and membrane integrity, was notably reduced by alcohol stress. While LPS is important for OmpC trimerisation, LPS release by EDTA did not lower OmpC levels. This suggests that LPS release, which is reported under alcohol stress, does not contribute to the reduced levels of OmpC in the presence of alcohol.ConclusionsSince alcohol primarily targets the integrity of the membrane, maintenance of outer membrane OmpC levels in the presence of alcohol might help in the survival of E. coli to higher alcohol concentrations. The study provides important information about the membrane protein responses of E. coli to a range of alcohols, which can be used to develop targeted strategies for increased microbial alcohol tolerance and hence bioalcohol production.

Insight into microbial functional genes’ role in geochemical distribution and cycling of uranium: The evidence from covering soils of uranium tailings dam

There exists a research gap on microbial functional genes’ role in U geochemical behavior and cycling in U contaminated soils, which has been poorly understood. Herein, 16S rRNA sequencing gene amplifiers and metagenome analysis were applied to probe microbial community structure and functional metabolism of different depth layers of covering soils in U tailings dam. Results showed that the soils were highly enriched with U (47.5–123.3 mg/kg) and a remarkable portion of 35–70% was associated with the labile fractions. It was found that U geochemical distribution was notably interacted with functional genes from N, S, Fe and P related microbes. Importantly, diminution in gene NirK and amplification in nrfH involving in nitrate reduction could induce microbial tolerance to U. Moreover, gene Sat in microbial sulfate reduction, NosZ and NorB in nitrate reduction, phnD, upgA and upgC in P transportation and phnI, phnK, phoA and opd in microbial organic P mineralization, were all closely linked to U geochemical distribution, species and cycling. All these findings disclose the functional genes that may control the transfer and transformation behavior of U in soil environment, which provides important and novel indications for the bio-remediation strategies towards U polluted sites.

Enhancing microbial salt tolerance through low-voltage stimulation for improved p-chloronitrobenzene (p-CNB) removal in high-salinity wastewater

As an important raw material for the synthesis of chemical and pharmaceutical, hazardous carcinogen p-chloronitrobenzene (p-CNB) has been widely found in high-salinity wastewater which need to be treated carefully. Due to the high-salinity shock on microorganisms, conventional microbial treatment technologies usually show poor effluent quality. This study initially investigated the p-CNB removal performance of microorganisms stimulated by 1.2 V low-voltage in high-salinity wastewater under facultative anaerobic conditions and further revealed the enhanced mechanisms. The results showed that the p-CNB removal kinetic parameter kp-CNB in the electrostimulating microorganism reactor (EMR) increased by 104.37 % to 155.30 % compared to the microorganism reactor (MR) as the control group under the varying salinities (0–45 g/L NaCl). The secretion of extracellular polymeric substances (EPS) in halotolerant microorganisms mainly enhanced by 1.2 V voltage stimulation ranging from 0 g/L NaCl to 30 g/L NaCl. Protein concentration ratio of EMR to MR in loosely bound EPS achieved maximum value of 1.77 at the salinity of 15 g/L NaCl, and the same ratio in tightly bound EPS also peaked at 1.39 under the salinity of 30 g/L NaCl. At the salinity of 45 g/L NaCl, 1.2 V voltage stimulation mainly enhanced salt-in strategy of halotolerant microorganisms, and the intracellular Na+ and K+ concentration ratio of EMR to MR reached maximum and minimum values of 0.65 and 1.92, respectively. Furthermore, the results of microbial metagenomic and metatranscriptomic analysis showed the halotolerant microorganisms Pseudomonas_A and Nitratireductor with p-CNB removal ability were enriched significantly under 1.2 V voltage stimulation. And the gene expression of p-CNB removal, salt-in strategy and betaine transporter were enhanced under voltage stimulation at varying salinities. Our investigation provided a new solution which combined with 1.2 V voltage stimulation and halotolerant microorganisms for the treatment of high-salinity wastewater.

Butea monosperma Silver Nanoparticles Anticancer Activity Against MCF 7 Human Breast Cancer Cell Line

In this research, silver nanoparticles were synthesized from Butea monosperma for in vitro cytotoxicity efficacy against MCF-7 cells. Silver nanoparticles are deemed the most positive, considering their strong volume surface region, and are of concern for study because of the improved microbial tolerance to antibiotics and medicines. Therefore, green synthesis of nanoparticles of silver using biomolecules derived from various plant sources in the form of extracts can be applied for the screening of different diseases which trigger microorganisms and for the physical and biological characterization of plant-derived silver nanoparticles. The experiment involved the green synthesis of silver nanoparticles (AgNPs) from Butea monosperma leaf extract. Biosynthesized Butea monosperma-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The intensity of peak broad range 200-800nm in UV-vis spectra, EDS test. The SEM shows the actual size of the nanoparticles. The MTT assays were carried out for cytotoxicity of various concentrations of biosynthesized silver nanoparticles. The biosynthesized silver nanoparticles showed a significant anticancer activity against both MCF-7. Our study thus revealed an excellent application of greenly synthesized silver nanoparticles. At the Concentration 80µg/ml, Sample Code A, B, C, D samples showed good percent inhibition MCF7cell line as compared to standard drug.The study also suggested the potential therapeutic use of these nanoparticles in cancer study.