Complex gene response of herbicide-resistant Enterobacter strain NRS-1 under different glyphosate stresses. - Related Documents




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882301.0000Complex gene response of herbicide-resistant Enterobacter strain NRS-1 under different glyphosate stresses. Knowledge of biological evolution and genetic mechanisms is gained by studying the adaptation of bacteria to survive in adverse environmental conditions. In this regard, transcriptomic profiling of a glyphosate-tolerant Enterobacter strain NRS-1 was studied under four different treatments to investigate the gene-regulatory system for glyphosate tolerance. A total of 83, 83, 60 and 74 genes were up-regulated and 108, 87, 178 and 117 genes down-regulated under 60-NPG, 110-NPG, NaCl (355 mM) and HCl (pH 4.46) stress treatments, respectively. Complex gene network was identified to be involved in regulating tolerance to glyphosate. This study revealed that NRS-1 has gained glyphosate tolerance at the cost of osmotic and acidic resistance. The 25 differentially expressed genes are reported to may have partly changed the function for providing resistance to glyphosate directly, among them genes metK, mtbK, fdnG and wzb that might detoxify/degrade the glyphosate. However, under 110-NPG condition, NRS-1 might have utilized economical and efficient ways by depressing its metabolism and activity to pass through this stress. Hence, the present study provides insights into the genes involved in glyphosate tolerance, which can be effectively utilized to engineer herbicide-resistant crop varieties after their proper validation to manage weed growth.201830305993
868410.9988Multiple Transcriptional Mechanisms Collectively Mediate Copper Resistance in Cupriavidus gilardii CR3. Bacteria resist copper (Cu) stress by implementing several metabolic mechanisms. However, these mechanisms are not fully understood. We investigated the mechanism of Cu resistance in Cupriavidus gilardii CR3, a Cu-resistant bacterium with a fully sequenced, annotated genome. The growth of CR3 was inhibited by higher Cu concentrations (≥1.0 mM) but not by lower ones (≤0.5 mM). CR3 accumulated Cu intracellularly (ratios of intercellular to extracellular Cu were 11.6, 4.24, and 3.9 in 0.1, 0.5, and 1.5 mM Cu treatments, respectively). A comparative transcriptome analysis of CR3 respectively revealed 310 and 413 differentially expressed genes under 0.5 and 1.5 mM Cu stress, most of which were up-regulated under Cu treatment. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses uncovered several genotype-specific biological processes related to Cu stress. Besides revealing known Cu resistance-related genes, our global transcriptomics approach indicated that sulfur metabolism, iron-sulfur cluster, and cell secretion systems are involved in mediating Cu resistance in strain CR3. These results suggest that bacteria collectively use multiple systems to cope with Cu stress. Our findings concerning the global transcriptome response to Cu stress in CR3 provide new information for understanding the intricate regulatory network of Cu homeostasis in prokaryotes.201930920814
881720.9988Study on the estradiol degradation gene expression and resistance mechanism of Rhodococcus R-001 under low-temperature stress. Estradiol (E2), an endocrine disruptor, acts by mimicking or interfering with the normal physiological functions of natural hormones within organisms, leading to issues such as endocrine system disruption. Notably, seasonal fluctuations in environmental temperature may influence the degradation speed of estradiol (E2) in the natural environment, intensifying its potential health and ecological risks. Therefore, this study aims to explore how bacteria can degrade E2 under low-temperature conditions, unveiling their resistance mechanisms, with the goal of developing new strategies to mitigate the threat of E2 to health and ecological safety. In this paper, we found that Rhodococcus equi DSSKP-R-001 (R-001) can efficiently degrade E2 at 30 °C and 10 °C. Six genes in R-001 were shown to be involved in E2 degradation by heterologous expression at 30 °C. Among them, 17β-HSD, KstD2, and KstD3, were also involved in E2 degradation at 10 °C; KstD was not previously known to degrade E2. RNA-seq was used to characterize differentially expressed genes (DEGs) to explore the stress response of R-001 to low-temperature environments to elucidate the strain's adaptation mechanism. At the low temperature, R-001 cells changed from a round spherical shape to a long rod or irregular shape with elevated unsaturated fatty acids and were consistent with the corresponding genetic changes. Many differentially expressed genes linked to the cold stress response were observed. R-001 was found to upregulate genes encoding cold shock proteins, fatty acid metabolism proteins, the ABC transport system, DNA damage repair, energy metabolism and transcriptional regulators. In this study, we demonstrated six E2 degradation genes in R-001 and found for the first time that E2 degradation genes have different expression characteristics at 30 °C and 10 °C. Linking R-001 to cold acclimation provides new insights and a mechanistic basis for the simultaneous degradation of E2 under cold stress in Rhodococcus adaptation.202438677604
868330.9988Responses to copper stress in the metal-resistant bacterium Cupriavidus gilardii CR3: a whole-transcriptome analysis. Microbial metal-resistance mechanisms are the basis for the application of microorganisms in metal bioremediation. Despite the available studies of bacterial molecular mechanisms to resistance metals ions (particularly copper), the understanding of bacterial metal resistance is very limited from the transcriptome perspective. Here, responses of the transcriptome (RNA-Seq) was investigated in Cupriavidus gilardii CR3 exposed to 0.5 mM copper, because strain CR3 had a bioremoval capacity of 38.5% for 0.5 mM copper. More than 24 million clean reads were obtained from six libraries and were aligned against the C. gilardii CR3 genome. A total of 310 genes in strain CR3 were significantly differentially expressed under copper stress. Apart from the routine copper resistance operons cus and cop known in previous studies, Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses of differentially expressed genes indicated that the adenosine triphosphate-binding cassette transporter, amino acid metabolism, and negative chemotaxis collectively contribute to the copper-resistant process. More interestingly, we found that the genes associated with the type III secretion system were induced under copper stress. No such results were reordered in bacteria to date. Overall, this comprehensive network of copper responses is useful for further studies of the molecular mechanisms underlying responses to copper stress in bacteria.201930900763
868040.9987Environmental 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
868550.9986Transcriptome analysis of an arsenite-/antimonite-oxidizer, Bosea sp. AS-1 reveals the importance of the type 4 secretion system in antimony resistance. Bosea sp. AS-1 is an arsenite [As(III)] and antimonite [Sb(III)] oxidizer previously isolated by our group from the Xikuangshan Antimony (Sb) Mine area. Our previous study showed that Bosea sp. AS-1 had a preference for oxidizing As(III) or Sb(III) with different carbon sources, which suggested that different metabolic mechanisms may be utilized by the bacteria to survive in As(III)- or Sb(III)-contaminated environments. Here, we conducted whole-genome and transcriptome sequencing to reveal the molecular mechanisms utilized by Bosea sp. AS-1 to resist As(III) or Sb(III). We discovered that AS-1 acquired various As- and Sb-resistant genes in its genome and might resist As(III) or Sb(III) through the regulation of multiple pathways, such as As and Sb metabolism, the bacterial secretion system, oxidative phosphorylation, the TCA cycle and bacterial flagellar motility. Interestingly, we discovered that genes of the type IV secretion system (T4SS) were activated in response to Sb(III), and inhibiting T4SS activity in AS-1 dramatically reduced its oxidation efficiency and tolerance to Sb(III). To our knowledge, this is the first study showing the activation of T4SS genes by Sb and a direct involvement of T4SS in bacterial Sb resistance. Our findings establish the T4SS as an important Sb resistance factor in bacteria and may help us understand the spread of Sb resistance genes in the environment.202235231521
68360.9986Integrative Multiomics Analysis of the Heat Stress Response of Enterococcus faecium. A continuous heat-adaptation test was conducted for one Enterococcus faecium (E. faecium) strain wild-type (WT) RS047 to obtain a high-temperature-resistant strain. After domestication, the strain was screened with a significantly higher ability of heat resistance. which is named RS047-wl. Then a multi-omics analysis of transcriptomics and metabolomics was used to analyze the mechanism of the heat resistance of the mutant. A total of 98 differentially expressed genes (DEGs) and 115 differential metabolites covering multiple metabolic processes were detected in the mutant, which indicated that the tolerance of heat resistance was regulated by multiple mechanisms. The changes in AgrB, AgrC, and AgrA gene expressions were involved in quorum-sensing (QS) system pathways, which regulate biofilm formation. Second, highly soluble osmotic substances such as putrescine, spermidine, glycine betaine (GB), and trehalose-6P were accumulated for the membrane transport system. Third, organic acids metabolism and purine metabolism were down-regulated. The findings can provide target genes for subsequent genetic modification of E. faecium, and provide indications for screening heat-resistant bacteria, so as to improve the heat-resistant ability of E. faecium for production.202336979372
886870.9985Effects of Stress, Reactive Oxygen Species, and the SOS Response on De Novo Acquisition of Antibiotic Resistance in Escherichia coli. Strategies to prevent the development of antibiotic resistance in bacteria are needed to reduce the threat of infectious diseases to human health. The de novo acquisition of resistance due to mutations and/or phenotypic adaptation occurs rapidly as a result of interactions of gene expression and mutations (N. Handel, J. M. Schuurmans, Y. Feng, S. Brul, and B. H. Ter Kuile, Antimicrob Agents Chemother 58:4371-4379, 2014, http://dx.doi.org/10.1128/AAC.02892-14). In this study, the contribution of several individual genes to the de novo acquisition of antibiotic resistance in Escherichia coli was investigated using mutants with deletions of genes known to be involved in antibiotic resistance. The results indicate that recA, vital for the SOS response, plays a crucial role in the development of antibiotic resistance. Likewise, deletion of global transcriptional regulators, such as gadE or soxS, involved in pH homeostasis and superoxide removal, respectively, can slow the acquisition of resistance to a degree depending on the antibiotic. Deletion of the transcriptional regulator soxS, involved in superoxide removal, slowed the acquisition of resistance to enrofloxacin. Acquisition of resistance occurred at a lower rate in the presence of a second stress factor, such as a lowered pH or increased salt concentration, than in the presence of optimal growth conditions. The overall outcome suggests that a central cellular mechanism is crucial for the development of resistance and that genes involved in the regulation of transcription play an essential role. The actual cellular response, however, depends on the class of antibiotic in combination with environmental conditions.201526666928
612180.9985Complete genome of Sphingomonas paucimobilis ZJSH1, an endophytic bacterium from Dendrobium officinale with stress resistance and growth promotion potential. Sphingomonas paucimobilis ZJSH1 is an endophytic bacterium isolated from the roots of Dendrobium officinale with the ability to promote plant growth. It was found that the genome of strain ZJSH1 had gene fragment rearrangement compared with the genomes of the other four strains of S. paucimobilis, and the genome was integrated with phage genes. Functional analysis showed that the strain contained colonization-related genes, chemotaxis and invasion. A variety of genes encoding active materials, such as hormones (IAA, SA, ABA and zeaxanthin), phosphate cycle, antioxidant enzymes, and polysaccharides were identified which provide the strain with growth promotion and stress-resistant characteristics. Experiments proved that S. paucimobilis ZJSH1 grew well in media containing 80 g/L sodium chloride, 240 g/L polyethylene glycol and 800 μmol/L Cd(2+), indicating its potential for resistance to stresses of salt, drought and cadmium, respectively. S. paucimobilis ZJSH1 is the only endophytic bacterium of this species that has been reported to promote plant growth. The analysis of its genome is conducive to understanding its growth-promoting mechanism and laying a foundation for the development and utilization of this species in the field of agriculture.202336959350
881990.9985Responses 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
690100.9984Characterization of oxidative stress-resistant mutants of Streptococcus thermophilus CNRZ368. During industrial processes, the dairy organism Streptococcus thermophilus is exposed to stress conditions. Its ability to survive and grow in an aerobic environment indicates that it must possess defensive mechanisms against reactive oxygen species. To identify the genes involved in oxidative stress defence, a collection of mutants was generated by random insertional mutagenesis and screened for menadione sensitivity and resistance. Results obtained for resistant clones allowed the identification of eight loci. The insertions affected genes whose homologues in other bacteria were previously identified as being involved in stress response(deoB, gst) or transcription regulation (rggC) and five ORFs of unknown function. The tolerance of the eight mutants to air-exposure, methyl viologen and H2O2 was studied. Real-time quantitative PCR was used to analyse the transcript level of mutated genes and revealed that most were down-regulated during oxidative stress.200415378231
8686110.9984Improving Cadmium Resistance in Escherichia coli Through Continuous Genome Evolution. Cadmium (Cd) is a heavy metal that is extremely toxic to many organisms; however, microbes are highly adaptable to extreme conditions, including heavy metal contamination. Bacteria can evolve in the natural environment, generating resistant strains that can be studied to understand heavy-metal resistance mechanisms, but obtaining such adaptive strains usually takes a long time. In this study, the genome replication engineering assisted continuous evolution (GREACE) method was used to accelerate the evolutionary rate of the Escherichia coli genome to screen for E. coli mutants with high resistance to cadmium. As a result, a mutant (8mM-CRAA) with a minimum inhibitory concentration (MIC) of 8 mM cadmium was generated; this MIC value was approximately eightfold higher than that of the E. coli BL21(DE3) wild-type strain. Sequencing revealed 329 single nucleotide polymorphisms (SNPs) in the genome of the E. coli mutant 8mM-CRAA. These SNPs as well as RNA-Seq data on gene expression induced by cadmium were used to analyze the genes related to cadmium resistance. Overexpression, knockout and mutation of the htpX (which encodes an integral membrane heat shock protein) and gor (which encodes glutathione reductase) genes revealed that these two genes contribute positively to cadmium resistance in E. coli. Therefore, in addition to the previously identified cadmium resistance genes zntA and capB, many other genes are also involved in bacterial cadmium resistance. This study assists us in understanding the mechanism of microbial cadmium resistance and facilitating the application of heavy-metal remediation.201930842762
170120.9984Effect of arsenite and growth in biofilm conditions on the evolution of Thiomonas sp. CB2. Thiomonas bacteria are ubiquitous at acid mine drainage sites and play key roles in the remediation of water at these locations by oxidizing arsenite to arsenate, favouring the sorption of arsenic by iron oxides and their coprecipitation. Understanding the adaptive capacities of these bacteria is crucial to revealing how they persist and remain active in such extreme conditions. Interestingly, it was previously observed that after exposure to arsenite, when grown in a biofilm, some strains of Thiomonas bacteria develop variants that are more resistant to arsenic. Here, we identified the mechanisms involved in the emergence of such variants in biofilms. We found that the percentage of variants generated increased in the presence of high concentrations of arsenite (5.33 mM), especially in the detached cells after growth under biofilm-forming conditions. Analysis of gene expression in the parent strain CB2 revealed that genes involved in DNA repair were upregulated in the conditions where variants were observed. Finally, we assessed the phenotypes and genomes of the subsequent variants generated to evaluate the number of mutations compared to the parent strain. We determined that multiple point mutations accumulated after exposure to arsenite when cells were grown under biofilm conditions. Some of these mutations were found in what is referred to as ICE19, a genomic island (GI) carrying arsenic-resistance genes, also harbouring characteristics of an integrative and conjugative element (ICE). The mutations likely favoured the excision and duplication of this GI. This research aids in understanding how Thiomonas bacteria adapt to highly toxic environments, and, more generally, provides a window to bacterial genome evolution in extreme environments.202033034553
8879130.9984Global 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
6293140.9984Gentamicin 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
251150.9984Deep sequencing analysis of the Kineococcus radiotolerans transcriptome in response to ionizing radiation. Kineococcus radiotolerans is a gram-positive, radiation-resistant bacterium that was isolated from a radioactive environment. The synergy of several groups of genes is thought to contribute to the radio-resistance of this species of bacteria. Sequencing of the transcriptome, RNA sequencing (RNA-seq), using deep sequencing technology can reveal the genes that are differentially expressed in response to radiation in this bacterial strain. In this study, the transcriptomes of two samples (with and without irradiation treatment) were sequencing by deep sequencing technology. After the bioinformatics process, 143 genes were screened out by the differential expression (DE) analysis. In all 143 differentially expressed genes, 20 genes were annotated to be related to the radio-resistance based on the cluster analysis by the cluster of orthologous groups of proteins (COG) annotation which were validated by the quantitative RT-PCR. The pathway analysis revealed that these 20 validated genes were related to DNA damage repair, including recA, ruvA and ruvB, which were considered to be the key genes in DNA damage repair. This study provides the foundation to investigate the regulatory mechanism of these genes.201525467197
6339160.9984Novel acid resistance genes from the metagenome of the Tinto River, an extremely acidic environment. Microorganisms that thrive in acidic environments are endowed with specialized molecular mechanisms to survive under this extremely harsh condition. In this work, we performed functional screening of six metagenomic libraries from planktonic and rhizosphere microbial communities of the Tinto River, an extremely acidic environment, to identify genes involved in acid resistance. This approach has revealed 15 different genes conferring acid resistance to Escherichia coli, most of which encoding putative proteins of unknown function or previously described proteins not known to be related to acid resistance. Moreover, we were able to assign function to one unknown and three hypothetical proteins. Among the recovered genes were the ClpXP protease, the transcriptional repressor LexA and nucleic acid-binding proteins such as an RNA-binding protein, HU and Dps. Furthermore, nine of the retrieved genes were cloned and expressed in Pseudomonas putida and Bacillus subtilis and, remarkably, most of them were able to expand the capability of these bacteria to survive under severe acid stress. From this set of genes, four presented a broad-host range as they enhance the acid resistance of the three different organisms tested. These results expand our knowledge about the different strategies used by microorganisms to survive under extremely acid conditions.201323145860
8682170.9984Role 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
682180.9984Comparative transcriptome analysis of Brucella melitensis in an acidic environment: Identification of the two-component response regulator involved in the acid resistance and virulence of Brucella. Brucella melitensis, encounters a very stressful environment in phagosomes, especially low pH levels. So identifying the genes that contribute to the replication and survival within an acidic environment is critical in understanding the pathogenesis of the Brucella bacteria. In our research, comparative transcriptome with RNA-seq were used to analyze the changes of genes in normal-medium culture and in pH4.4-medium culture. The results reveal that 113 genes expressed with significant differences (|log2Ratio| ≥ 3); about 44% genes expressed as up-regulated. With GO term analysis, structural constituent of the ribosome, rRNA binding, structural molecule activity, and cation-transporting ATPase activity were significantly enriched (p-value ≤ 0.05). These genes distributed in 51 pathways, in which ribosome and photosynthesis pathways were significantly enriched. Six pathways (oxidative phosphorylation, iron-transporting, bacterial secretion system, transcriptional regulation, two-component system, and ABC transporters pathways) tightly related to the intracellular survival and virulence of Brucella were analyzed. A two-component response regulator gene in the transcriptional regulation pathway, identified through gene deletion and complementary technologies, played an important role in the resistance to the acid-resistance and virulence of Brucella.201626691825
8811190.9984Mechanisms controlling the transformation of and resistance to mercury(II) for a plant-associated Pseudomonas sp. strain, AN-B15. Bioremediation using mercury (Hg)-volatilizing and immobilizing bacteria is an eco-friendly and cost-effective strategy for Hg-polluted farmland. However, the mechanisms controlling the transformation of and resistance to Hg(II) by these bacteria remain unknown. In this study, a plant-associated Pseudomonas sp. strain, AN-B15 was isolated and determined to effectively remove Hg(II) under both nutrient-poor and nutrient-rich conditions via volatilization by transforming Hg(II) to Hg(0) and immobilization by transforming Hg(II) to mercury sulfide and Hg-sulfhydryl. Genome and transcriptome analyses revealed that the molecular mechanisms involved in Hg(II) resistance in AN-B15 were a collaborative process involving multiple metabolic systems at the transcriptional level. Under Hg(II) stress, AN-B15 upregulated genes involved in the mer operon and producing the reducing power to rapidly volatilize Hg(II), thereby decreasing its toxicity. Hydroponic culture experiments also revealed that inoculation with strain AN-B15 alleviated Hg-induced toxicity and reduced the uptake of Hg(II) in the roots of wheat seedlings, as explained by the volatilization and immobilization of Hg(II) and plant growth-promoting traits of AN-B15. Overall, the results from the in vitro assays provided vital information that are essential for understanding the mechanism of Hg(II) resistance in plant-associated bacteria, which can also be applied for the bioremediation of Hg-contamination in future.202234915295