Docosahexaenoic acid inhibits pheromone-responsive-plasmid-mediated conjugative transfer of antibiotic resistance genes in Enterococcus faecalis. - Related Documents




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675901.0000Docosahexaenoic acid inhibits pheromone-responsive-plasmid-mediated conjugative transfer of antibiotic resistance genes in Enterococcus faecalis. The rapid spread of antibiotic-resistance genes (ARGs) in Enterococcus faecalis (E. faecalis) poses a great challenge to human health and ecological and environmental safety. Therefore, it is important to control the spread of ARGs. In this study, we observed that the addition of 5 μg/mL docosahexaenoic acid (DHA) reduced the conjugative transfer of pCF10 plasmid by more than 95% in E. faecalis. DHA disturbed the pheromone transport by inhibiting the mRNA levels of the prgZ gene, causing the iCF10 pheromone to accumulate in the donor bacteria and bond to the PrgX receptor to form an inhibitory phase, which resulted in the down-regulation of the expression of genes related to conjugative transfer, inhibiting biofilm formation, reducing bacterial adhesion and thus inhibiting conjugative transfer. Collectively, DHA exhibited an admirable inhibitory effect on the transfer of ARGs in E. faecalis. This study provided a technical option to control the transfer of ARGs.202336423456
895110.9996Response mechanisms of resistance in L-form bacteria to different target antibiotics: Implications from oxidative stress to metabolism. Due to the specific action on bacterial cell wall, β-lactam antibiotics have gained widespread usage as they exhibit a high degree of specificity in targeting bacteria, but causing minimal toxicity to host cells. Under antibiotic pressure, bacteria may opt to shed their cell walls and transform into L-form state as a means to evade the antibiotic effects. In this study, we explored and identified diverse optimal conditions for both Gram-negative bacteria (E. coli DH5α (CTX)) and Gram-positive bacteria (B. subtilis ATCC6633), which were induced to L-form bacteria using lysozyme (0.5 ppm) and meropenem (64 ppm). Notably, when bacteria transformed into L-form state, both bacterial strains showed varying degrees of increased resistance to antibiotics polymyxin E, meropenem, rifampicin, and tetracycline. E. coli DH5α (CTX) exhibited the most significant enhancement in resistance to tetracycline, with a 128-fold increase, while B. subtilis ATCC6633 showed a 32-fold increase in resistance to tetracycline and polymyxin E. Furthermore, L-form bacteria maintained their normal metabolic activity, combined with enhanced oxidative stress, served as an adaptive strategy promoting the sustained survival of L-form bacteria. This study provided a theoretical basis for comprehending antibiotic resistance mechanisms, developing innovative treatment strategies, and confronting global antibiotic resistance challenges.202438735077
676320.9996Sub-lethal photocatalysis promotes horizontal transfer of antibiotic resistance genes by conjugation and transformability. The spread of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in water is increasingly becoming a worldwide problem due to frequent recent major public health events. Herein, the horizontal ARG transfer mechanisms were studied under sub-lethal photocatalysis. The results show that ARGs had at most a 3- to 6-fold increase in the conjugative transfer frequency when only donor bacteria were induced with sub-lethal photocatalysis, while the frequency exhibited a trend toward inhibition when only the recipient bacteria were induced. However, when the donor or recipient bacteria were induced beforehand for a specific time, the frequency increased by a maximum of 10- to 22-fold. Moreover, the horizontal transfer frequency and its mechanism were related to the oxidative stress systems, ATP systems and the expression of related genes. Furthermore, the transformability of extracellular plasmids of the ARB and the contribution in horizontal transfer were also studied. Results show that the transformation frequency accounted for up to 50% of the total number of transconjugants, indicating that transformation might be a primary mode of horizontal ARG transfer by ARB in water. All of the above results demonstrate that sub-lethal photocatalysis will increase the frequency of horizontal gene transfer of ARGs through both conjugative transfer and the transformation pathway, which increases the risk of ARB in aquatic environments.202235841790
676130.9996Exposure to Al(2)O(3) nanoparticles facilitates conjugative transfer of antibiotic resistance genes from Escherichia coli to Streptomyces. The spread of antibiotic resistance genes (ARGs) has become a global environmental issue; it has been found that nanoparticles (NPs) can promote the transfer of ARGs between bacteria. However, it remains unclear whether NPs can affect this kind of conjugation in Streptomyces, which mainly conjugate with other bacteria via spores. In the present study, we demonstrated that Al(2)O(3) NPs significantly promote the conjugative transfer of ARGs from Escherichia coli (E. coli) ET12567 to Streptomyces coelicolor (S. coelicolor) M145 without the use of heat shock method. The number of transconjugants induced by Al(2)O(3) particles was associated with the size and concentration of Al(2)O(3) particles, exposure time, and the ratio of E. coli and spores. When nanoparticle size was 30 nm at a concentration of 10 mg/L, the conjugation efficiency reached a peak value of 182 cfu/10(8) spores, which was more than 60-fold higher than that of the control. Compared with nanomaterials, bulk particles exhibited no significant effect on conjugation efficiency. We also explored the mechanisms by which NPs promote conjugative transfer. After the addition of NPs, the intracellular ROS content increased and the expression of the classical porin gene ompC was stimulated. In addition, ROS enhanced the mRNA expression levels of conjugative genes by inhibiting global regulation genes. Meanwhile, expression of the conjugation-related gene intA was also stimulated, ultimately increasing the number of transconjugants. Our results indicated that Al(2)O(3) NPs significantly promoted the conjugative transfer of ARGs from bacteria to spores and aggravated the diffusion of resistance genes in the environment.201931561730
674540.9996Decreased Antibiotic Susceptibility in Pseudomonas aeruginosa Surviving UV Irradition. Given its excellent performance against the pathogens, UV disinfection has been applied broadly in different fields. However, only limited studies have comprehensively investigated the response of bacteria surviving UV irradiation to the environmental antibiotic stress. Here, we investigated the antibiotic susceptibility of Pseudomonas aeruginosa suffering from the UV irradiation. Our results revealed that UV exposure may decrease the susceptibility to tetracycline, ciprofloxacin, and polymyxin B in the survival P. aeruginosa. Mechanistically, UV exposure causes oxidative stress in P. aeruginosa and consequently induces dysregulation of genes contributed to the related antibiotic resistance genes. These results revealed that the insufficient ultraviolet radiation dose may result in the decreased antibiotic susceptibility in the pathogens, thus posing potential threats to the environment and human health.202133613479
678150.9996Antibiotic-resistance gene transfer in antibiotic-resistance bacteria under different light irradiation: Implications from oxidative stress and gene expression. Due to the significant public health risks, there is substantial scientific interest in the increasing abundance of antibiotic-resistance bacteria (ARB) and the spread of antibiotic-resistance genes (ARGs) in aquatic environments. To clearly understand the mechanism of ARG transfer, this study examined the conjugative transfer of genes encoding resistance to cephalosporin (bla(CTX)) and polymyxin (mcr-1) from two antibiotic-resistant donor strains, namely E. coli DH5α (CTX) and E. coli DH5α (MCR), and to a streptomycin-resistant receptor strain (E. coli C600 (Sm)). Conjugative transfer was specifically studied under different light irradiation conditions including visible light (VL), simulated sunlight (SS) and ultraviolet light (UV(254nm)). Results show that the conjugative transfer frequency was not affected by VL irradiation, while it was slightly improved (2-10 fold) by SS irradiation and extremely accelerated (up to 100 fold) by UV irradiation. Furthermore, this study also explored the link between ARG transfer and stress conditions. This was done by studying physiological and biochemical changes; oxidative stress response; and functional gene expression of co-cultured AR-E. coli strains under stress conditions. When correlated with the transfer frequency results, we found that VL irradiation did not affect the physiological and biochemical characteristics of the bacteria, or induce oxidative stress and gene expression. For SS irradiation, oxidative stress occurred slowly, with a slight increase in the expression of target genes in the bacterial cells. In contrast, UV irradiation, rapidly inactivated the bacteria, the degree of oxidative stress was very severe and the expression of the target genes was markedly up-regulated. Our study could provide new insight into the underlying mechanisms and links between accelerated conjugative transfer and oxidative stress, as well as the altered expression of genes relevant to conjugation and other stress responses in bacterial cells.201930465986
379460.9996Effect of Caenorhabditis elegans age and genotype on horizontal gene transfer in intestinal bacteria. Horizontal gene transfer (HGT) between bacteria occurs in the intestinal tract of their animal hosts and facilitates both virulence and antibiotic resistance. A model in which both the pathogen and the host are genetically tractable facilitates developing insight into mechanistic processes enabling or restricting the transfer of antibiotic resistance genes. Here we develop an in vivo experimental system to study HGT in bacteria using Caenorhabditis elegans as a model host. Using a thermosensitive conjugative system, we provide evidence that conjugation between two Escherichia coli strains can take place in the intestinal lumen of N2 wild-type worms at a rate of 10(-3) and 10(-2) per donor. We also show that C. elegans age and genotype are important determinants of the frequency of conjugation. Whereas ∼1 transconjugant for every 100 donor cells could be recovered from the intestine of N2 C. elegans, for the age-1 and tol-1 mutants, the detected rate of transconjugation (10(-3) and 10(-4) per donor cell, respectively) was significantly lower. This work demonstrates that increased recombination among lumenal microbial populations is a phenotype associated with host aging, and the model provides a framework to study the dynamics of bacterial horizontal gene transfer within the intestinal environment.201323085995
926470.9996Nanoalumina promotes the horizontal transfer of multiresistance genes mediated by plasmids across genera. Antibiotic resistance is a worldwide public health concern. Conjugative transfer between closely related strains or species of bacteria is an important method for the horizontal transfer of multidrug-resistance genes. The extent to which nanomaterials are able to cause an increase in antibiotic resistance by the regulation of the conjugative transfer of antibiotic-resistance genes in bacteria, especially across genera, is still unknown. Here we show that nanomaterials in water can significantly promote the horizontal conjugative transfer of multidrug-resistance genes mediated by the RP4, RK2, and pCF10 plasmids. Nanoalumina can promote the conjugative transfer of the RP4 plasmid from Escherichia coli to Salmonella spp. by up to 200-fold compared with untreated cells. We also explored the mechanisms behind this phenomenon and demonstrate that nanoalumina is able to induce oxidative stress, damage bacterial cell membranes, enhance the expression of mating pair formation genes and DNA transfer and replication genes, and depress the expression of global regulatory genes that regulate the conjugative transfer of RP4. These findings are important in assessing the risk of nanomaterials to the environment, particularly from water and wastewater treatment systems, and in the estimation of the effect of manufacture and use of nanomaterials on the environment.201222411796
898180.9996Response mechanisms of different antibiotic-resistant bacteria with different resistance action targets to the stress from photocatalytic oxidation. The stress response of antibiotic-resistant bacteria (ARB) and the spread of antibiotic resistance genes (ARGs) pose a serious threat to the aquatic environment and human beings. This study mainly explored the effect of the heterogeneous photocatalytic oxidation (UVA-TiO(2) system) on the stress response mechanism of ARB with different antibiotic resistance action targets, including the cell wall, proteins, DNA, RNA, folate and the cell membrane. Results indicate that the stress response mechanism of tetracycline- and sulfamethoxazole-resistant E. coli DH5α, which targets the synthesis of protein and folate, could rapidly induce global regulators by the overexpression of relative antibiotic resistance action target genes. Different stress response systems were mediated via cross-protection mechanism, causing stronger tolerance to an adverse environment than other ARB. Moreover, the photocatalytic inactivation mechanism of bacterial cells and a graded response of cellular stress mechanism caused differences in the intensity of the stress mechanism of antibiotic resistance action targets. E. coli DH5α resistant to cefotaxime and polymyxin, targeting synthesis of the cell wall and cell membrane, respectively, could confer greater advantages to bacterial survival and higher conjugative transfer frequency than E. coli DH5α resistant to nalidixic acid and rifampicin, which target the synthesis of DNA and RNA, respectively. This new perspective provides detailed information on the practical application of photocatalytic oxidation for inactivating ARB and hampering the spreading of ARGs in the aquatic environment.202235453030
379790.9996Human intestinal cells modulate conjugational transfer of multidrug resistance plasmids between clinical Escherichia coli isolates. Bacterial conjugation in the human gut microbiota is believed to play a major role in the dissemination of antibiotic resistance genes and virulence plasmids. However, the modulation of bacterial conjugation by the human host remains poorly understood and there is a need for controlled systems to study this process. We established an in vitro co-culture system to study the interaction between human intestinal cells and bacteria. We show that the conjugation efficiency of a plasmid encoding an extended spectrum beta-lactamase is reduced when clinical isolates of Escherichia coli are co-cultured with human intestinal cells. We show that filtered media from co-cultures contain a factor that reduces conjugation efficiency. Protease treatment of the filtered media eliminates this inhibition of conjugation. This data suggests that a peptide or protein based factor is secreted on the apical side of the intestinal cells exposed to bacteria leading to a two-fold reduction in conjugation efficiency. These results show that human gut epithelial cells can modulate bacterial conjugation and may have relevance to gene exchange in the gut.201424955767
9270100.9996Activation of class 1 integron integrase is promoted in the intestinal environment. Class 1 integrons are widespread genetic elements playing a major role in the dissemination of antibiotic resistance. They allow bacteria to capture, express and exchange antibiotic resistance genes embedded within gene cassettes. Acquisition of gene cassettes is catalysed by the class 1 integron integrase, a site-specific recombinase playing a key role in the integron system. In in vitro planktonic culture, expression of intI1 is controlled by the SOS response, a regulatory network which mediates the repair of DNA damage caused by a wide range of bacterial stress, including antibiotics. However, in vitro experimental conditions are far from the real lifestyle of bacteria in natural environments such as the intestinal tract which is known to be a reservoir of integrons. In this study, we developed an in vivo model of intestinal colonization in gnotobiotic mice and used a recombination assay and quantitative real-time PCR, to investigate the induction of the SOS response and expression and activity of the class 1 integron integrase, IntI1. We found that the basal activity of IntI1 was higher in vivo than in vitro. In addition, we demonstrated that administration of a subinhibitory concentration of ciprofloxacin rapidly induced both the SOS response and intI1 expression that was correlated with an increase of the activity of IntI1. Our findings show that the gut is an environment in which the class 1 integron integrase is induced and active, and they highlight the potential role of integrons in the acquisition and/or expression of resistance genes in the gut, particularly during antibiotic therapy.202235482826
8984110.9996Environmental peracetic acid increases antibiotic resistance in Streptococcus Suis. Disinfectants in the environment have important impacts on the occurrence of antibiotic resistant bacteria, posing a new threat to public health. Streptococcus suis (S. suis) can survive in the environment for three months and carries antibiotic resistance genes. However, it remains unclear whether disinfectants directly induce antibiotic resistance in S. suis. Here, we conducted induction experiments on the S. suis standard strain (CVCC609) with eight disinfectants at different concentrations and investigated their effects on the antibiotic resistance mechanism of S. suis. The results showed that only 64 mg L(-1) peracetic acid (PAA) led to an increase (8-fold) in S. suis resistance to tiamulin (TIA) with genetic stability. The treatment also induced significant changes in the morphology and capsule of the mutant strains, as well as triggered an increase in reactive oxygen species and biofilms in bacterial cells, resulting in an emergency response. Moreover, PAA significantly decreased the cell membrane permeability and led to slight changes in the adenosine triphosphate level. The key differentially expressed genes are closely related to these resistance mechanisms. These results reveal the co-selection mechanism of S. suis resistance to PAA and TIA, and highlight the importance of standardized application of disinfectants in livestock and poultry farming.202540286665
3798120.9996Genome-Wide Association Study Reveals Host Factors Affecting Conjugation in Escherichia coli. The emergence and dissemination of antibiotic resistance threaten the treatment of common bacterial infections. Resistance genes are often encoded on conjugative elements, which can be horizontally transferred to diverse bacteria. In order to delay conjugative transfer of resistance genes, more information is needed on the genetic determinants promoting conjugation. Here, we focus on which bacterial host factors in the donor assist transfer of conjugative plasmids. We introduced the broad-host-range plasmid pKJK10 into a diverse collection of 113 Escherichia coli strains and measured by flow cytometry how effectively each strain transfers its plasmid to a fixed E. coli recipient. Differences in conjugation efficiency of up to 2.7 and 3.8 orders of magnitude were observed after mating for 24 h and 48 h, respectively. These differences were linked to the underlying donor strain genetic variants in genome-wide association studies, thereby identifying candidate genes involved in conjugation. We confirmed the role of fliF, fliK, kefB and ucpA in the donor ability of conjugative elements by validating defects in the conjugation efficiency of the corresponding lab strain single-gene deletion mutants. Based on the known cellular functions of these genes, we suggest that the motility and the energy supply, the intracellular pH or salinity of the donor affect the efficiency of plasmid transfer. Overall, this work advances the search for targets for the development of conjugation inhibitors, which can be administered alongside antibiotics to more effectively treat bacterial infections.202235336183
7629130.9995Graphene oxide in the water environment could affect tetracycline-antibiotic resistance. In recent years, the influence of new materials like nanoparticles in the water environment on biological substances has been widely studied. Antibiotic resistance genes (ARGs) represent a new type of pollutant in the environment. Graphene oxide (GO), as a nano material, because of its unique structure, may have an impact on antibiotic resistance bacteria (ARB) and ARGs; however the research in this area is rarely reported. Therefore, this study mainly investigated the effects of GO on bacterial antibiotic resistance. The results showed that GO had a limited effect on ARB inactivation. A high concentration of GO (>10 mg/L) can damage resistant plasmids to reduce bacterial resistance to antibiotics, but low concentrations of GO (<1 mg/L) led to almost no damage to the plasmid. However, all tested concentrations of GO promoted the conjugative transfer from 1to over 3 folds, with low concentrations and high concentration (1-10 and 100 mg/L) of GO samples the least promoted. The overall effect of GO on antibiotic resistance needs further investigation.201728549325
3802140.9995Exposure to One Antibiotic Leads to Acquisition of Resistance to Another Antibiotic via Quorum Sensing Mechanisms. The vancomycin-resistant Enterococci (VRE) have progressively become a severe medical problem. Although clinics have started to reduce vancomycin prescription, vancomycin resistance has not been contained. We found that the transfer of vancomycin resistance in Enterococcus faecalis increased more than 30-fold upon treatment by streptomycin. Notably, treatment with an antibiotic caused the bacteria to become resistant to another. The response was even stronger in the well-studied plasmid pCF10 and the number of transconjugants increased about 100,000-fold. We tested four different antibiotics, and all of them induced conjugal response. Through a mathematical model based on gene regulation, we found a plausible explanation. Via quorum sensing, the change of the cell density triggers the conjugation. Moreover, we searched for generality and found a similar strategy in Bacillus subtilis. The outcome of the present study suggests that even common antibiotics must not be overused.202033552007
8502150.9995Simultaneously disinfection of amoebae, endosymbiotic bacteria, and resistance genes using a novel two-electron water oxidation strategy. Amoebae, which serve as important vectors for various pathogenic bacteria, are ubiquitous in natural and artificial water systems. Their robust survival capabilities and protective characteristics render conventional disinfection methods largely ineffective. Moreover, amoeba cells provide an ideal environment for the replication and transfer of antibiotic resistance genes, posing a significant threat to human health and safety. In this study, an in-situ activation system for electrocatalytic water oxidation was developed. This system effectively inactivates amoeba spores and their intracellular symbiotic bacteria while simultaneously reducing the abundance of resistance genes through the generation of hydroxyl radicals (•OH) and carbonate free radicals (•CO(3)(-)). The results demonstrated a 99.9 % inactivation rate for amoeba spores and a 99.999 % inactivation rate for intracellular bacteria. In addition, the prevalence of resistant genes in bacteria within amoebae, specifically including sul1 (sulfonamide resistance), tetA (tetracycline resistance), blaFOX (cefoxitin resistance), arsB (arsenic resistance), czcA (cadmium resistance), and copA (copper resistance), was significantly reduced by approximately 16 %-62.6 %. Therefore, this study introduces a new technology capable of simultaneously treating amoeba spores, intracellular bacteria, and resistance genes, which holds significant importance for reducing the spread of resistant genes and enhancing public health safety.202540449332
6762160.9995Impacts of particle size and surface charge of ZnO on horizontal transformation of antibiotic resistance genes. The ever-growing antibiotic resistance in bacteria poses an enormous threat to public health and the environment. The horizontal transfer of antibiotic resistance genes (ARGs) is a major pathway for disseminating antibiotic resistance. As an inexpensive, nontoxic, and biocompatible material, ZnO with diverse sizes and surface properties have been prepared for widespread use. However, the effects and mechanisms of ZnO particles with different structural properties on the horizontal transfer of ARGs are not comprehensively understood. In this study, two groups of ZnO particles, one with the same size (93 nm) and different charge types (-9.5 and + 17.4 mV), and the other homogeneously positively charged but of different sizes (93, 215, and 2381 nm), were prepared. Their impacts on the horizontal transformation of ARGs mediated by plasmid pUC19 into E coli DH5α were investigated. In the positively charged group, the smallest ZnO nanoparticles at concentrations of 0.1-100 μg/mL induced 1.04-1.35 and 1.37-1.71-fold increases in transformation frequency when compared with that of the medium-sized and largest particles, respectively. In the similar-sized groups, positive ZnO promoted 1.06-1.32-fold increases than negative ZnO. Further investigation suggested that smaller and positive ZnO adsorbed more plasmids and correspondingly increased the uptake by recipient bacteria than that of larger and/or negative ZnO. In addition, the enhanced bacterial membrane permeability, ATP synthesis, and DNA replication were also accounted for the increased transformation. These results suggest that smaller-sized and positive ZnO poses a high environmental risk of spreading antibiotic resistance.202540527433
8952170.9995Correlation between the development of phage resistance and the original antibiotic resistance of host bacteria under the co-exposure of antibiotic and bacteriophage. Bacteriophages (phages) are viruses capable of regulating the proliferation of antibiotic resistant bacteria (ARB). However, phages that directly cause host lethality may quickly select for phage resistant bacteria, and the co-evolutionary trade-offs under varying environmental conditions, including the presence of antibiotics, remains unclear as to their impact on phage and antibiotic resistance. Here, we report the emergence of phage resistance in three distinct E. coli strains with varying resistance to β-lactam antibiotics, treated with different ampicillin (AMP) concentrations. Hosts exhibiting stronger antibiotic resistance demonstrated a higher propensity to develop and maintain stable phage resistance. When exposed to polyvalent phage KNT-1, the growth of AMP-sensitive E. coli K12 was nearly suppressed within 18 h, while the exponential growth of AMP-resistant E. coli TEM and super-resistant E. coli NDM-1 was delayed by 12 h and 8 h, respectively. The mutation frequency and mutated colony count of E. coli NDM-1 were almost unaffected by co-existing AMP, whereas for E. coli TEM and K12, these metrics significantly decreased with increasing AMP concentration from 8 to 50 μg/mL, becoming unquantifiable at 100 μg/mL. Furthermore, the fitness costs of phage resistance mutation and its impact on initial antibiotic resistance in bacteria were further examined, through analyzing AMP susceptibility, biofilm formation and EPS secretion of the isolated phage resistant mutants. The results indicated that acquiring phage resistance could decrease antibiotic resistance, particularly for hosts lacking strong antibiotic resistance. The ability of mutants to form biofilm contributes to antibiotic resistance, but the correlation is not entirely positive, while the secretion of extracellular polymeric substance (EPS), especially the protein content, plays a crucial role in protecting the bacteria from both antibiotic and phage exposure. This study explores phage resistance development in hosts with different antibiotic resistance and helps to understand the limitations and possible solutions of phage-based technologies.202438631474
3793180.9995Physicochemical Factors That Favor Conjugation of an Antibiotic Resistant Plasmid in Non-growing Bacterial Cultures in the Absence and Presence of Antibiotics. Horizontal gene transfer (HGT) of antibiotic resistance genes has received increased scrutiny from the scientific community in recent years owing to the public health threat associated with antibiotic resistant bacteria. Most studies have examined HGT in growing cultures. We examined conjugation in growing and non-growing cultures of E. coli using a conjugative multi antibiotic and metal resistant plasmid to determine physiochemical parameters that favor horizontal gene transfer. The conjugation frequency in growing and non-growing cultures was generally greater under shaken than non-shaken conditions, presumably due to increased frequency of cell collisions. Non-growing cultures in 9.1 mM NaCl had a similar conjugation frequency to that of growing cultures in Luria-Bertaini broth, whereas those in 1 mM or 90.1 mM NaCl were much lower. This salinity effect on conjugation was attributed to differences in cell-cell interactions and conformational changes in cell surface macromolecules. In the presence of antibiotics, the conjugation frequencies of growing cultures did not increase, but in non-growing cultures of 9.1 mM NaCl supplemented with Cefotaxime the conjugation frequency was as much as nine times greater than that of growing cultures. The mechanism responsible for the increased conjugation in non-growing bacteria was attributed to the likely lack of penicillin-binding protein 3 (the target of Cefotaxime), in non-growing cells that enabled Cefotaxime to interact with the plasmid and induce conjugation. Our results suggests that more attention may be owed to HGT in non-growing bacteria as most bacteria in the environment are likely not growing and the proposed mechanism for increased conjugation may not be unique to the bacteria/plasmid system we studied.201830254617
6778190.9995Bisphenol S Promotes the Transfer of Antibiotic Resistance Genes via Transformation. The antibiotic resistance crisis has seriously jeopardized public health and human safety. As one of the ways of horizontal transfer, transformation enables bacteria to acquire exogenous genes naturally. Bisphenol compounds are now widely used in plastics, food, and beverage packaging, and have become a new environmental pollutant. However, their potential relationship with the spread of antibiotic resistance genes (ARGs) in the environment remains largely unexplored. In this study, we aimed to assess whether the ubiquitous bisphenol S (BPS) could promote the transformation of plasmid-borne ARGs. Using plasmid pUC19 carrying the ampicillin resistance gene as an extracellular ARG and model microorganism E. coli DH5α as the recipient, we established a transformation system. Transformation assays revealed that environmentally relevant concentrations of BPS (0.1-10 μg/mL) markedly enhanced the transformation frequency of plasmid-borne ARGs into E. coli DH5α up to 2.02-fold. Fluorescent probes and transcript-level analyses suggest that BPS stimulated increased reactive oxygen species (ROS) production, activated the SOS response, induced membrane damage, and increased membrane fluidity, which weakened the barrier for plasmid transfer, allowing foreign DNA to be more easily absorbed. Moreover, BPS stimulates ATP supply by activating the tricarboxylic acid (TCA) cycle, which promotes flagellar motility and expands the search for foreign DNA. Overall, these findings provide important insight into the role of bisphenol compounds in facilitating the horizontal spread of ARGs and emphasize the need to monitor the residues of these environmental contaminants.202439337307