Role of manganese superoxide dismutase (Mn-SOD) against Cr(III)-induced toxicity in bacteria. - Related Documents




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868201.0000Role of manganese superoxide dismutase (Mn-SOD) against Cr(III)-induced toxicity in bacteria. The toxicity of Cr(VI) was widely investigated, but the defense mechanism against Cr(III) in bacteria are seldom reported. Here, we found that Cr(III) inhibited bacterial growth and induced reactive oxygen species (ROS). After exposure to Cr(III), loss of sodA not only led to the excessive generation of ROS, but also enhanced the level of lipid peroxidation and reduced the GSH level, indicating that the deficiency of Mn-SOD decreased the bacterial resistance ability against Cr(III). The adverse effects of oxidative stress caused by Cr(III) could be recovered by the rescue of Mn-SOD in the sodA-deficient strain. Besides the oxidative stress, Cr(III) could cause the bacterial morphology variation, which was distinct between the wild-type and the sodA-deficient strains due to the differential expressions of Z-ring division genes. Moreover, Mn-SOD might prevent Cr(III) from oxidation on the bacterial surface by combining with Cr(III). Taken together, our results indicated that the Mn-SOD played a vital role in regulating the stress resistance, expression of cell division-related genes, bacterial morphology, and chemistry valence state of Cr. Our findings firstly provided a more in-depth understanding of Cr(III) toxicity and bacterial defense mechanism against Cr(III).202132781281
868110.9997The regulatory mechanism of Chryseobacterium sp. resistance mediated by montmorillonite upon cadmium stress. Cadmium (Cd) is a toxic heavy metal and its uptake by living organisms causes adverse effect, further resulting in cycle pollution of the biosphere. The specific regulatory mechanism between clays and microbes under Cd stress remains unclear. In this study, interface interactions among clays, microbes and Cd were confirmed. Comparative transcriptome was conducted to investigate how it regulated gene expression patterns of microbes (Chryseobacterium sp. WAL2), which exposed to a series of gradient concentrations of Cd (16, 32, 64 and 128 μg mL(-1)) for 12 d in the presence and absence of clay montmorillonite (Mt) (16 g L(-1)). Cd was highly enriched by the unique interface interactions between Mt and bacteria (67.6-82.1%), leading to a more hostile environment for bacterial cells. However, Mt ultimately enhanced bacterial resistance to Cd stress by stimulating the mechanism of bacterial resistance; namely: (i) Mt increased genes expression connected with ion transport, enhancing the uptake of Cd; (ii) Mt stimulated genes expression related to efflux pump and positively regulated cellular oxidative stress (e.g., glutathione) and Cd accumulation (e.g., cysteine) processes. Further, genes expression related to intracellular metabolic processes was enforced, which supplied a driving force and accelerated electron transfer; (iii) Mt improved genes expression involved in DNA replication and other biological processes (e.g., terpenoid backbone biosynthesis) to maintain bacterial vitality. Therefore, the study not only optimized a unique Cd resistance mechanism of Mt on Chryseobacterium sp., but also provided a novel insight for environmental mitigation of heavy metals from the perspective of molecular biology.202031546187
868020.9997Environmental pH affects transcriptional responses to cadmium toxicity in Escherichia coli K-12 (MG1655). It has been widely reported that pH mediates cadmium toxicity to bacteria. We used a tripartite approach to investigate mechanisms by which pH affects cadmium toxicity that included analyses of: (1) growth kinetics, (2) global gene expression, and (3) cadmium speciation. Cadmium extended the lag phase at pH 7, but not at pH 5. DNA microarray analysis revealed that stress response genes including hdeA, otsA, and yjbJ were more highly expressed at pH 5 than at pH 7 after only 5 min of exposure to cadmium, suggesting that acidic pH more rapidly induced genes that confer cadmium resistance. In addition, genes involved in transport and many hypothetical genes were more highly expressed at pH 5 than at pH 7 in the presence of cadmium. Concentrations of two cadmium species, including one previously implicated in the mechanism by which pH mediates cadmium toxicity (CdOH+), increased with pH. Our data demonstrate that transcriptional responses of Escherichia coli to cadmium are substantially affected by pH and suggest that several stress response, transport, and hypothetical genes play roles in the mechanism by which pH mediates cadmium toxicity.200919220470
881930.9997Responses of Bacillus sp. under Cu(II) stress in relation to extracellular polymeric substances and functional gene expression level. The production and composition of extracellular polymeric substances (EPS), as well as the EPS-related functional resistance genes and metabolic levels of Bacillus sp. under Cu(II) stress, were investigated. EPS production increased by 2.73 ± 0.29 times compared to the control when the strain was treated with 30 mg L(-1) Cu(II). Specifically, the polysaccharide (PS) content in EPS increased by 2.26 ± 0.28 g CDW(-1) and the PN/PS (protein/polysaccharide) ratio value increased by 3.18 ± 0.33 times under 30 mg L(-1) Cu(II) compared to the control. The increased EPS secretion and higher PN/PS ratio in EPS strengthened the cells' ability to resist the toxic effect of Cu(II). Differential expression of functional genes under Cu(II) stress was revealed by Gene Ontology pathway enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The enriched genes were most obviously upregulated in the UMP biosynthesis pathway, the pyrimidine metabolism pathway, and the TCS metabolism pathway. This indicates an enhancement of EPS regulation-related metabolic levels and their role as a defense mechanism for cells to adapt to Cu(II) stress. Additionally, seven copper resistance genes were upregulated while three were downregulated. The upregulated genes were related to the heavy metal resistance, while downregulated genes were related to cell differentiation, indicating that the strain had initiated an obvious resistance to Cu(II) despite its severe cell toxicity. These results provided a basis for promoting EPS-regulated associated functional genes and the application of gene-regulated bacteria in heavy metal-containing wastewater treatment.202337195605
898240.9997Ampicillin Exposure and Glutathione Deficiency Synergistically Promote Conjugative Transfer of Plasmid-Borne Antibiotic Resistance Genes. Plasmid-mediated conjugation is an important pathway for the spread of antibiotic resistance genes (ARGs), posing a significant risk to global public health. It has been reported that the conjugative transfer of ARGs could be enhanced by oxidative stress. Whether endogenous glutathione (GSH), a major non-protein thiol compound involved in cellular redox homeostasis, influences conjugative transfer is unknown. In this study, we show that the deletion of the GSH biosynthesis gene gshA and ampicillin exposure synergistically promoted the conjugative transfer of plasmid RP4 bearing multiple ARGs from the soil bacterium Enterobacter sp. CZ-1 to Escherichia coli S17-1λπ in co-culture experiments and to diverse soil bacteria belonging to eight phyla, including some potential human pathogens, in a soil incubation experiment. The deletion of gshA increased ROS generation and cell membrane permeability, and upregulated the expression of the genes involved in intracellular oxidative stress regulation, membrane permeability, plasmid replication, and the SOS response process, especially under ampicillin exposure. These results suggest that endogenous GSH is an important factor affecting the spread of plasmid-borne ARGs. Exposure to antibiotics and environmental stresses that cause a depletion of endogenous GSH in vivo are likely to increase the risk of ARG dissemination in the environment.202540346915
814950.9997Genes related to antioxidant metabolism are involved in Methylobacterium mesophilicum-soybean interaction. The genus Methylobacterium is composed of pink-pigmented methylotrophic bacterial species that are widespread in natural environments, such as soils, stream water and plants. When in association with plants, this genus colonizes the host plant epiphytically and/or endophytically. This association is known to promote plant growth, induce plant systemic resistance and inhibit plant infection by phytopathogens. In the present study, we focused on evaluating the colonization of soybean seedling-roots by Methylobacterium mesophilicum strain SR1.6/6. We focused on the identification of the key genes involved in the initial step of soybean colonization by methylotrophic bacteria, which includes the plant exudate recognition and adaptation by planktonic bacteria. Visualization by scanning electron microscopy revealed that M. mesophilicum SR1.6/6 colonizes soybean roots surface effectively at 48 h after inoculation, suggesting a mechanism for root recognition and adaptation before this period. The colonization proceeds by the development of a mature biofilm on roots at 96 h after inoculation. Transcriptomic analysis of the planktonic bacteria (with plant) revealed the expression of several genes involved in membrane transport, thus confirming an initial metabolic activation of bacterial responses when in the presence of plant root exudates. Moreover, antioxidant genes were mostly expressed during the interaction with the plant exudates. Further evaluation of stress- and methylotrophic-related genes expression by qPCR showed that glutathione peroxidase and glutathione synthetase genes were up-regulated during the Methylobacterium-soybean interaction. These findings support that glutathione (GSH) is potentially a key molecule involved in cellular detoxification during plant root colonization. In addition to methylotrophic metabolism, antioxidant genes, mainly glutathione-related genes, play a key role during soybean exudate recognition and adaptation, the first step in bacterial colonization.201526238382
888060.9996Nisin and acid resistance in Salmonella is enhanced by N-dodecanoyl-homoserine lactone. Salmonella is a foodborne pathogen that can develop resistance to different stresses, which is essential for successful infection of the host. Some genes directly related to acid resistance are also involved in cationic peptide resistance in Gram-negative bacteria and could be under the control of quorum sensing (QS) mediated by autoinducer 1, known as acyl-homoserine lactone. Here, we investigated the influence of autoinducer 1, N-dodecanoyl-homoserine lactone (C12-HSL) on the resistance of Salmonella enterica subspecies enterica serovar Enteritidis to nisin and acid stress. Salmonella cells growing in anaerobic tryptic soy agar (TSB) at a pH of 7.0 for 7 h were submitted to acid stress at a pH of 4.5 in the presence and absence of nisin and were either supplemented or not with C12-HSL. Viable cell counts, gene expression, membrane charge alterations, fatty acid composition, and intracellular content leakage were observed. The autoinducer C12-HSL increased nisin resistance and survival at a pH of 4.5 in Salmonella. Also, C12-HSL increased the expression of the genes, phoP, phoQ, pmrA, and pmrB, which are involved with antimicrobial and acid resistance. The positive charge on the cell surface and concentration of cyclopropane fatty acid of the cellular membrane were increased in the presence of C12-HSL under acidic conditions, whereas membrane fluidity decreased. The loss of K(+) and NADPH, promoted by nisin, was reduced in the presence of C12-HSL at a pH of 4.5. Taken together, these findings suggest that quorum sensing plays an important role in enhanced nisin and acid resistance in Salmonella.202032534181
867970.9996Metal accumulation in cell wall: a possible mechanism of cadmium resistance by Pseudomonas stutzeri. A heavy metal resistant strain, Pseudomonas stutzeri (MTCC 101) has been investigated for its cadmium tolerance properties along with its antibiotic resistance. The organism could tolerate cadmium up to 1,200 μg/mL with LD50 value 700 μg/mL. The gene(s) involved in such high resistance appear(s) to be induced in the presence of the metal. Increasing concentrations of cadmium successively prolonged the lag phase of growth with delayed attainment of the stationary phase. Transmission electron microscope and scanning electron microscope-energy dispersive analysis of X-ray spectroscope analysis showed cadmium adsorption on the bacterial surface with morphological distortion. Atomic absorption spectrometric study corroborated this data, showing highest cadmium accumulation in the cell wall fraction of the bacteria. Additionally, the cell wall fraction showed synthesis of new proteins when grown under metal stress.201323275974
896780.9996Distinct transcriptomic response of S. coelicolor to ciprofloxacin in a nutrient-rich environment. With the rising threat of anti-microbial resistance (AMR), there is an urgent need to enhance efficacy of existing antibiotics. Understanding the myriad mechanisms through which bacteria evade these drugs would be of immense value to designing novel strategies against them. Streptomyces coelicolor A3(2) M145 belongs to the actinomyctes species that are responsible for more than two-thirds of antibiotics. This group of bacteria therefore encodes for various mechanisms that can resist both endogenous and non-endogenous antibiotics. In an earlier study, we had studied the transcriptomic response of these bacteria to ciprofloxacin, when cultured in a minimal media. In this work, we investigate why the minimum inhibitory concentration of the drug increases by fourfold when the bacteria are grown in a nutrient-rich media. Through transcriptomic, biochemical, and microscopic studies, we show that S. coelicolor responds to ciprofloxacin in a concentration-dependent manner. While, sub-inhibitory concentration of the drug primarily causes oxidative stress, the inhibitory concentration of ciprofloxacin evokes a more severe genome-wide response in the cell, which ranges from the familiar upregulation of the SOS response and DNA repair pathways to the widespread alterations in the central metabolism pathway to accommodate the increased needs of nucleotides and other precursors. Further, the upregulation of peptidoglycan synthesis genes, along with microscopy images, suggest alterations in the cell morphology to increase fitness of the bacteria during the antibiotic stress. The data also points to the enhanced efflux activity in cells cultured in rich media that contributes significantly towards reducing intracellular drug concentration and thus promotes survival.201830327831
898390.9996Chlorine disinfectants promote microbial resistance in Pseudomonas sp. The substantial use of disinfectants has increased antibiotic resistance, thereby mediating serious ecological safety issues worldwide. Accumulating studies have reported the role of chlorine disinfectants in promoting disinfectant resistance. The present study sought to investigate the role of chlorine disinfectants in developing multiple resistance in Pseudomonas sp. isolated from the river through antioxidant enzyme measurement, global transcriptional analyses, Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The results demonstrated that 100 mg/L sodium hypochlorite could increase disinfectant resistance and antibiotic resistance. The SOS response (a conserved response to DNA damage) triggered by oxidative stress makes bacteria resistant to chlorine. An increase in antibiotic resistance could be attributed to a decreased membrane permeability, increased expression of MuxABC-OpmB efflux pump, beta-lactamase, and antioxidant enzymes. Additionally, KEGG enrichment analysis suggested that the differentially expressed genes were highly enriched in the metabolic pathways. In summary, the study results revealed the impact of chlorine disinfectants in promoting microbial disinfectant resistance and antibiotic resistance. This study will provide insight into disinfectant resistance mechanisms.202134010624
8942100.9996Indole-Induced Activities of β-Lactamase and Efflux Pump Confer Ampicillin Resistance in Pseudomonas putida KT2440. Indole, which is widespread in microbial communities, has received attention because of its effects on bacterial physiology. Pseudomonas putida and Pseudomonas aeruginosa can acquire ampicillin (Amp) resistance during growth on indole-Amp agar. Transcriptome, mutant, and inhibitor studies have suggested that Amp resistance induced by indole can be attributed to increased gene expression of ttgAB encoding two genes of RND-type multidrug efflux operons and an ampC encoding β-lactamase. Expression, enzyme activities, and mutational analyses indicated that AmpC β-lactamase is important for acquiring Amp resistance of P. putida in the presence of indole. Here, we show, for the first time, that volatile indole increased Amp-resistant cells. Consistent with results of the volatile indole assay, a low concentration of indole in liquid culture promoted growth initially, but led to mutagenesis after indole was depleted, which could not be observed at high indole concentrations. Interestingly, ttgAB and ampC gene expression levels correlate with the concentration of indole, which might explain the low number of Amp-mutated cells in high indole concentrations. The expression levels of genes involved in mutagenesis, namely rpoS, recA, and mutS, were also modulated by indole. Our data indicates that indole reduces Amp-induced heterogeneity by promoting expression of TtgABC or MexAB-OprM efflux pumps and the indole-induced β-lactamase in P. putida and P. aeruginosa.201728352264
6738110.9996Combined effects of microplastics and antibiotic-resistant bacteria on Daphnia magna growth and expression of functional genes. Microplastics could act as vectors for the transport of harmful bacteria, such as pathogens and antibiotic resistance bacteria (ARB), but their combined effects have not been reported yet. Here, ARB Shigella flexneri with sulfonamides resistance and micro-polystyrene (micro-PS) were used to investigate their possible combined effects on the growth and expression of functional genes in Daphnia magna. Results showed that micro-PS colonized with S. flexneri were ingested by D. magna and blocked in their intestine after 24 h exposure. Changes were observed in the life history and morphology of D. magna, as well as the expression of functional genes in all treatments, but with no difference in the survival rate. We also determined the expression of six functional genes involved in energy and metabolism (arginine kinase, AK) and oxidative stress response (thioredoxin reductase, TRxR, catalase, CAT, and glutathione S-transferases, GSTs), as well as in growth, development and reproduction (vitellogenin, Vtg1 and ecdysone receptor, EcR). AK and Vtg1 did not show significant differences, however, EcR was down-regulated and the other three genes (TRxR, CAT, GSTs) were up-regulated in the combined-treated group. Antibiotic resistance gene (ARGs) sul1 was detected when exposed to micro-PS colonized with S. flexneri., suggesting that D. magna could acquire resistance genes through microplastic biofilms. These results indicated that MPs could act as a carrier of ARB to transfer ARGs into D. magna, and affect the life history, morphology, and the expression of related functional genes of D. magna, to adapt to the stress caused by MPs and ARB.202337709097
6293120.9996Gentamicin resistance to Escherichia coli related to fatty acid metabolism based on transcriptome analysis. Antibiotic overuse and misuse have promoted the emergence and spread of antibiotic-resistant bacteria. Increasing bacterial resistance to antibiotics is a major healthcare problem, necessitating elucidation of antibiotic resistance mechanisms. In this study, we explored the mechanism of gentamicin resistance by comparing the transcriptomes of antibiotic-sensitive and -resistant Escherichia coli. A total of 410 differentially expressed genes were identified, of which 233 (56.83%) were up-regulated and 177 (43.17%) were down-regulated in the resistant strain compared with the sensitive strain. Gene Ontology (GO) analysis classifies differential gene expression into three main categories: biological processes, cellular components, and molecular functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the up-regulated genes were enriched in eight metabolic pathways, including fatty acid metabolism, which suggests that fatty acid metabolism may be involved in the development of gentamicin resistance in E. coli. This was demonstrated by measuring the acetyl-CoA carboxylase activity, plays a fundamental role in fatty acid metabolism, was increased in gentamicin-resistant E. coli. Treatment of fatty acid synthesis inhibitor, triclosan, promoted gentamicin-mediated killing efficacy to antibiotic-resistant bacteria. We also found that exogenous addition of oleic acid, which involved in fatty acid metabolism, reduced E. coli sensitivity to gentamicin. Overall, our results provide insight into the molecular mechanism of gentamicin resistance development in E. coli.202337224563
8965130.9996Resistance characterization and transcriptomic analysis of imipenem-induced drug resistance in Escherichia coli. BACKGROUND: Bacteria can develop resistance to various antibiotics under selective pressure, leading to multifaceted changes in resistance mechanisms. Transcriptomic sequencing allows for the observation of transcriptional level alterations in cells under antibiotic stress. Understanding the bacterial response to such stress is essential for deciphering their strategy against drug-resistant antibiotics and identifying potential targets for antibiotic development. METHODS: This study using wild-type (WT) Escherichia coli (E. coli) discovered that continuous in vitro induction screening for imipenem-resistant strains resulted in bacteria with enhanced biofilm-forming ability and mutations in antibiotic target sites. Transcriptomic sequencing of the resistant bacteria revealed significant changes in carbon and amino acid metabolism, nutrient assimilation, substance transport, nucleotide metabolism, protein biosynthesis, and cell wall biosynthesis. The up-regulated drug efflux genes were disrupted using gene knockout technology. Drug sensitivity tests indicated that drug efflux has a minimal effect on imipenem resistance. RESULTS: This suggests a strategy for E. coli drug resistance involving the reduction of unnecessary substance synthesis and metabolism, coupled with an increase in activities that aid in resisting foreign threats.202439624129
6754140.9996Real-time PCR based analysis of metal resistance genes in metal resistant Pseudomonas aeruginosa strain J007. A uranium (U)-resistant and -accumulating Pseudomonas aeruginosa strain was characterized to assess the response of toxic metals toward its growth and expression of metal resistance determinants. The bacterium showed MIC (minimum inhibitory concentration) values of 6, 3, and 2 mM for Zn, Cu, and Cd, respectively; with resistance phenotype conferred by periplasmic Cu sequestering copA and RND type heavy metal efflux czcA genes. Real-time PCR-based expression analysis revealed significant upregulation of both these genes upon exposure to low concentrations of metals for short duration, whereas the global stress response gene sodA encoding superoxide dismutase enzyme was upregulated only at higher metal concentrations or longer exposure time. It could also be inferred that copA and czcA are involved in providing resistance only at low metal concentrations, whereas involvement of "global stress response" phenomenon (expression of sodA) at higher metal concentration or increased exposure was evident. This study provides significant understanding of the adaptive response of bacteria surviving in metal and radionuclide contaminated environments along with the development of real-time PCR-based quantification method of using metal resistance genes as biomarker for monitoring relevant bacteria in such habitats.201626662317
720150.9996Escherichia Coli Increases its ATP Concentration in Weakly Acidic Environments Principally through the Glycolytic Pathway. Acid resistance is an intrinsic characteristic of intestinal bacteria in order to survive passage through the stomach. Adenosine triphosphate (ATP), the ubiquitous chemical used to power metabolic reactions, activate signaling cascades, and form precursors of nucleic acids, was also found to be associated with the survival of Escherichia coli (E. coli) in acidic environments. The metabolic pathway responsible for elevating the level of ATP inside these bacteria during acid adaptation has been unclear. E. coli uses several mechanisms of ATP production, including oxidative phosphorylation, glycolysis and the oxidation of organic compounds. To uncover which is primarily used during adaptation to acidic conditions, we broadly analyzed the levels of gene transcription of multiple E. coli metabolic pathway components. Our findings confirmed that the primary producers of ATP in E. coli undergoing mild acidic stress are the glycolytic enzymes Glk, PykF and Pgk, which are also essential for survival under markedly acidic conditions. By contrast, the transcription of genes related to oxidative phosphorylation was downregulated, despite it being the major producer of ATP in neutral pH environments.202032854287
6783160.9996Mechanism of earthworm coelomic fluid inhibits multidrug-resistant bacteria and blocks resistance transmission. Antibiotic resistance is a growing global health crisis, especially the spread of multi-drug resistance. In this study, the inhibitory effects of earthworm coelomic fluid (ECF) on multidrug-resistant bacteria (MRB) were investigated during employing vermicomposting to treat excess sludge generated from wastewater treatment. The results demonstrated that the ECF was able to inhibit, even completely decompose the MRB. Notably, when the ECF concentration reached 1.0 mg/mL, the intracellular reactive oxygen species (ROS) level increased by 46.7 %, while cell viability decreased by 55.2 % compared to the control, demonstrating that ECF exerts strong antibacterial activity by inducing oxidative stress and disrupting cellular homeostasis. Furthermore, ECF effectively degraded the DNA of MRB, with removal rates of aphA, KanR, and tetA reaching 51.8 %, 42.3 %, and 35.0 %, respectively, indicating its ability to eliminate resistance genes and hinder their potential transfer. Additionally, the upregulation of genes involved in signaling, DNA replication and repair, and energy metabolism pathways suggests a systemic stress response in MRB, further supporting the broad-spectrum inhibitory effects of ECF on bacterial viability and resistance maintenance. Taken together, these findings may open a door to naturally and ecologically combat antibiotic resistance in pollutants control in wastewater treatment.202540706790
8879170.9996Global metabolic regulation in Vibrio parahaemolyticus under polymyxin B stimulation. Vibrio parahaemolyticus is responsible for infection diseases of people who consume the contaminated seafood, but its metabolic regulation profile in response to colistin, the last treatment option for multidrug-resistant Gram-negative bacteria, remains unclear. In this study, the metabolic regulation profile of V. parahaemolyticus ATCC33846 under polymyxin B stimulation has been investigated. V. parahaemolyticus exposed to polymyxin B resulted in 4597 differentially transcribed genes, including 673 significantly up-regulated genes and 569 significantly down-regulated genes. In V. parahaemolyticus under polymyxin B stimulation, the cellular antioxidant systems to prevent bacteria from oxidant stress was activated, the synthesis of some nonessential macromolecules was reduced, and the assembly and modification of lipopolysaccharide and peptidoglycan to resist the attack from other antibiotics were promoted. These findings provide new insights into polymyxin B-related stress response in V. parahaemolyticus which should be useful for developing novel drugs for infection.202134688850
8301180.9996Metabolic disruption impairs ribosomal protein levels, resulting in enhanced aminoglycoside tolerance. Aminoglycoside antibiotics target ribosomes and are effective against a wide range of bacteria. Here, we demonstrated that knockout strains related to energy metabolism in Escherichia coli showed increased tolerance to aminoglycosides during the mid-exponential growth phase. Contrary to expectations, these mutations did not reduce the proton motive force or aminoglycoside uptake, as there were no significant changes in metabolic indicators or intracellular gentamicin levels between wild-type and mutant strains. Our comprehensive proteomics analysis unveiled a noteworthy upregulation of proteins linked to the tricarboxylic acid (TCA) cycle in the mutant strains during the mid-exponential growth phase, suggesting that these strains compensate for the perturbation in their energy metabolism by increasing TCA cycle activity to maintain their membrane potential and ATP levels. Furthermore, our pathway enrichment analysis shed light on local network clusters displaying downregulation across all mutant strains, which were associated with both large and small ribosomal binding proteins, ribosome biogenesis, translation factor activity, and the biosynthesis of ribonucleoside monophosphates. These findings offer a plausible explanation for the observed tolerance of aminoglycosides in the mutant strains. Altogether, this research provides valuable insights into the mechanisms of aminoglycoside tolerance, paving the way for novel strategies to combat such cells.202439093940
8304190.9996A Shift to Human Body Temperature (37°C) Rapidly Reprograms Multiple Adaptive Responses in Escherichia coli That Would Facilitate Niche Survival and Colonization. One of the first environmental cues sensed by a microbe as it enters a human host is an upshift in temperature to 37°C. In this dynamic time point analysis, we demonstrate that this environmental transition rapidly signals a multitude of gene expression changes in Escherichia coli. Bacteria grown at 23°C under aerobic conditions were shifted to 37°C, and mRNA expression was measured at time points after the shift to 37°C (t = 0.5, 1, and 4 h). The first hour is characterized by a transient shift to anaerobic respiration strategies and stress responses, particularly acid resistance, indicating that temperature serves as a sentinel cue to predict and prepare for various niches within the host. The temperature effects on a subset of stress response genes were shown to be mediated by RpoS and directly correlated with RpoS, DsrA, and RprA levels, and increased acid resistance was observed that was dependent on 23°C growth and RpoS. By 4 h, gene expression shifted to aerobic respiration pathways and decreased stress responses, coupled with increases in genes associated with biosynthesis (amino acid and nucleotides), iron uptake, and host defense. ompT, a gene that confers resistance to antimicrobial peptides, was highly thermoregulated, with a pattern conserved in enteropathogenic and uropathogenic E. coli strains. An immediate decrease in curli gene expression concomitant with an increase in flagellar gene expression implicates temperature in this developmental decision. Together, our studies demonstrate that temperature signals a reprogramming of gene expression immediately upon an upshift that may predict, prepare, and benefit the survival of the bacterium within the host. IMPORTANCE As one of the first cues sensed by the microbe upon entry into a human host, understanding how bacteria like E. coli modulate gene expression in response to temperature improves our understanding of how bacteria immediately initiate responses beneficial for survival and colonization. For pathogens, understanding the various pathways of thermal regulation could yield valuable targets for anti-infective chemotherapeutic drugs or disinfection measures. In addition, our data provide a dynamic examination of the RpoS stress response, providing genome-wide support for how temperature impacts RpoS through changes in RpoS stability and modulation by small regulatory RNAs.202134516284