Effects of free antibiotic resistance genes in the environment on intestinal microecology of mice. - Related Documents




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385501.0000Effects of free antibiotic resistance genes in the environment on intestinal microecology of mice. The rapid spread of antibiotic resistance genes (ARGs) is a great challenge to the ecological safety and human health. The intestine of humans and animals is an important site for the increase and spread of ARGs due to the great diversity and abundance of microorganisms in the intestinal microecology. ARGs, including the intracellular (iARGs) and the extracellular (eARGs) ARGs, are usually introduced into the intestinal tract through the diet, and the iARGs are colonized and spread in the intestinal microbiota with the help of the host bacteria. However, whether the eARGs can enter the intestinal microorganisms in the absence of host bacteria is not known. Here, we show the transformation and the diffusion of the ampramycin resistance gene (Ap) carried by the free plasmid RK2 in the intestinal microbiota of mice. After two days of consecutive gavage with free RK2, the intracellular Ap gene increases from days 0-8 in the feces of mice, and has remained constant. Bacterial transformation happens in the small intestine, including proximal and distal jejuna and proximal and distal ilea, at the early stage (first two days), and the intracellular RK2 is diffused into the intestinal microbiota of mice by conjugation on days 2-8 day, which is based on the distribution of eARG and iARG and the mRNA expression levels of trbBp, trfAp, korA, korB, and trbA. The characteristics of ARGs susceptible microbiota for transformation are analyzed using 16s rRNA gene sequencing, transmission electron microscopy, and flow cytometric. The ingestion of RK2 affects the composition of intestinal microbiota especially for Proteobacteria, and the antibiotic residue promotes the increase in Escherichia coli. These findings are important to assess the risk of ARGs, especially the eARGs in the intestinal microecology.202032798757
371410.9997Effect of conjugative transfer of antibiotic resistance genes mediated by plasmids on the microecology of different intestinal segments. INTRODUCTION: The conjugative transfer of antibiotic resistance genes (ARGs) mediated by plasmids occurred in different intestinal segments of mice was explored. METHODS: The location of ARG donor bacteria and ARGs was investigated by qPCR, flow cytometry, and small animal imaging. The resistant microbiota was analyzed by 16S rRNA gene amplification sequencing. RESULTS: The small intestine was the main site for the location of ARG donor bacteria and ARGs. The intestinal microbiota richness of the small intestine (duodenum and jejunum) and the large intestine (cecum, colon, and rectum) increased, and the ileum microbiota richness decreased under the action of donor bacteria. The differences in the number of bacteria in the small intestine and the large intestine, as well as the relative richness of Firmicutes from the small intestine to the large intestine, decreased. By contrast, the relative abundance of Proteobacteria increased. The intake of resistant plasmids alleviated the impact of antibiotics on intestinal microbiota, particularly increasing the proportion of Proteobacteria and Bacteroides, which were presumed to be susceptible to ARGs. DISCUSSION: The acquisition of ARGs by intestinal microbes is an important reason why infectious diseases are difficult to cure, which brings risks to human health and intestinal microecology.202439764443
752020.9997Antibiotic Resistance Gene-Carrying Plasmid Spreads into the Plant Endophytic Bacteria using Soil Bacteria as Carriers. Applications of animal manure and treated wastewater could enrich antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the plant microbiome. However, the mechanistic studies of the transmission of ARB and ARGs from the environment to plant endophytic bacteria were few. Herein, a genetically engineered fluorescent Escherichia coli harboring a conjugative RP4 plasmid that carries three ARGs was used to trace its spread into Arabidopsis thaliana interior in a tetracycline-amended hydroponic system in the absence or presence of a simulated soil bacterial community. Confocal microscope observation demonstrated that E. coli was internalized into plant tissues and the carried RP4 plasmid was transferred into plant endophytic bacteria. More importantly, we observed that soil bacteria inhibited the internalization of E. coli but substantially promoted RP4 plasmid spread into the plant microbiome. The altered RP4-carrying bacterial community composition in the plant microbiome and the increased core-shared RP4-carrying bacteria number between plant interior and exterior in the presence of soil bacteria collectively confirmed that soil bacteria, especially Proteobacteria, might capture RP4 from E. coli and then translocate into plant microbiome, resulting in the increased RP4 plasmid spread in the plant endophytes. Overall, our findings provided important insights into the dissemination of ARB and ARGs from the environment to the plant microbiome.202134114802
739930.9997Aquatic animals promote antibiotic resistance gene dissemination in water via conjugation: Role of different regions within the zebra fish intestinal tract, and impact on fish intestinal microbiota. The aqueous environment is one of many reservoirs of antibiotic resistance genes (ARGs). Fish, as important aquatic animals which possess ideal intestinal niches for bacteria to grow and multiply, may ingest antibiotic resistance bacteria from aqueous environment. The fish gut would be a suitable environment for conjugal gene transfer including those encoding antibiotic resistance. However, little is known in relation to the impact of ingested ARGs or antibiotic resistance bacteria (ARB) on gut microbiota. Here, we applied the cultivation method, qPCR, nuclear molecular genetic marker and 16S rDNA amplicon sequencing technologies to develop a plasmid-mediated ARG transfer model of zebrafish. Furthermore, we aimed to investigate the dissemination of ARGs in microbial communities of zebrafish guts after donors carrying self-transferring plasmids that encode ARGs were introduced in aquaria. On average, 15% of faecal bacteria obtained ARGs through RP4-mediated conjugal transfer. The hindgut was the most important intestinal region supporting ARG dissemination, with concentrations of donor and transconjugant cells almost 25 times higher than those of other intestinal segments. Furthermore, in the hindgut where conjugal transfer occurred most actively, there was remarkable upregulation of the mRNA expression of the RP4 plasmid regulatory genes, trbBp and trfAp. Exogenous bacteria seem to alter bacterial communities by increasing Escherichia and Bacteroides species, while decreasing Aeromonas compared with control groups. We identified the composition of transconjugants and abundance of both cultivable and uncultivable bacteria (the latter accounted for 90.4%-97.2% of total transconjugants). Our study suggests that aquatic animal guts contribute to the spread of ARGs in water environments.201728742284
752940.9997Fate of Antibiotic Resistant Pseudomonas putida and Broad Host Range Plasmid in Natural Soil Microcosms. Plasmid conjugation is one of the dominant mechanisms of horizontal gene transfer, playing a noticeable role in the rapid spread of antibiotic resistance genes (ARGs). Broad host range plasmids are known to transfer to diverse bacteria in extracted soil bacterial communities when evaluated by filter mating incubation. However, the persistence and dissemination of broad range plasmid in natural soil has not been well studied. In this study, Pseudomonas putida with a conjugative antibiotic resistance plasmid RP4 was inoculated into a soil microcosm, the fate and persistence of P. putida and RP4 were monitored by quantitative PCR. The concentrations of P. putida and RP4 both rapidly decreased within 15-day incubation. P. putida then decayed at a significantly lower rate during subsequent incubation, however, no further decay of RP4 was observed, resulting in an elevated RP4/P. putida ratio (up to 10) after 75-day incubation, which implied potential transfer of RP4 to soil microbiota. We further sorted RP4 recipient bacteria from the soil microcosms by fluorescence-activated cell sorting. Spread of RP4 increased during 75-day microcosm operation and was estimated at around 10(-4) transconjugants per recipient at the end of incubation. Analysis of 16S rRNA gene sequences of transconjugants showed that host bacteria of RP4 were affiliated to more than 15 phyla, with increased diversity and shift in the composition of host bacteria. Proteobacteria was the most dominant phylum in the transconjugant pools. Transient transfer of RP4 to some host bacteria was observed. These results emphasize the prolonged persistence of P. putida and RP4 in natural soil microcosms, and highlight the potential risks of increased spread potential of plasmid and broader range of host bacteria in disseminating ARGs in soil.201930881351
386150.9997Dietary intake of enrofloxacin promotes the spread of antibiotic resistance from food to simulated human gut. Antibiotic residues are commonly found in food. The effect of dietary exposure to veterinary antibiotics on the transmission of antibiotic resistant bacteria and antibiotic resistance genes from food to humans is unknown. We found that dietary exposure to enrofloxacin reduced microbial diversity, interactions and the immune responses, weakened the colonization resistance of the resident microbiota, and promoted the colonization of exogenous Escherichia coli K-12 MG1655 in the simulated human intestine both in vitro and in vivo experiments in mice. In addition to the growth advantages for potential most likely bacterial hosts of ARGs under enrofloxacin exposure, the dietary exposure to enrofloxacin promoted horizontal transfer of resistance plasmids and altered the simulated human gut antibiotic resistome in a time-dependent manner. Collectively, these findings demonstrated that dietary intake of enrofloxacin promoted the colonization of E. coli K-12 MG1655 in the simulated human intestine and the horizontal transfer of antibiotic resistance genes, highlighting the risk of antibiotic resistance transmission from food to humans mediated by dietary exposure to veterinary antibiotics.202540121546
676360.9997Sub-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
676470.9997Chlorine disinfection promotes the exchange of antibiotic resistance genes across bacterial genera by natural transformation. Chlorine disinfection to drinking water plays an important role in preventing and controlling waterborne disease outbreaks globally. Nevertheless, little is known about why it enriches the antibiotic resistance genes (ARGs) in bacteria after chlorination. Here, ARGs released from killed antibiotic-resistant bacteria (ARB), and culturable chlorine-injured bacteria produced in the chlorination process as the recipient, were investigated to determine their contribution to the horizontal transfer of ARGs during disinfection treatment. We discovered Escherichia coli, Salmonella aberdeen, Pseudomonas aeruginosa and Enterococcus faecalis showed diverse resistance to sodium hypochlorite, and transferable RP4 could be released from killed sensitive donor consistently. Meanwhile, the survival of chlorine-tolerant injured bacteria with enhanced cell membrane permeabilisation and a strong oxidative stress-response demonstrated that a physiologically competent cell could be transferred by RP4 with an improved transformation frequency of up to 550 times compared with the corresponding untreated bacteria. Furthermore, the water quality factors involving chemical oxygen demand (COD(Mn)), ammonium nitrogen and metal ions (Ca(2+) and K(+)) could significantly promote above transformation frequency of released RP4 into injured E. faecalis. Our findings demonstrated that the chlorination process promoted the horizontal transfer of plasmids by natural transformation, which resulted in the exchange of ARGs across bacterial genera and the emergence of new ARB, as well as the transfer of chlorine-injured opportunistic pathogen from non-ARB to ARB. Considering that the transfer elements were quite resistant to degradation through disinfection, this situation poses a potential risk to public health.202032327733
763780.9997High-sugar, high-fat, and high-protein diets promote antibiotic resistance gene spreading in the mouse intestinal microbiota. Diet can not only provide nutrition for intestinal microbiota, it can also remodel them. However, is unclear whether and how diet affects the spread of antibiotic resistance genes (ARGs) in the intestinal microbiota. Therefore, we employed selected high-sugar, high-fat, high-protein, and normal diets to explore the effect. The results showed that high-sugar, high-fat, and high-protein diets promoted the amplification and transfer of exogenous ARGs among intestinal microbiota, and up-regulated the expression of trfAp and trbBp while significantly altered the intestinal microbiota and its metabolites. Inflammation-related products were strongly correlated with the spread of ARGs, suggesting the intestinal microenvironment after diet remodeling might be conducive to the spreading of ARGs. This may be attributed to changes in bacterial membrane permeability, the SOS response, and bacterial composition and diversity caused by diet-induced inflammation. In addition, acceptor bacteria (zygotes) screened by flow cytometry were mostly Proteobacteria, Firmicutes and Actinobacteria, and most were derived from dominant intestinal bacteria remodeled by diet, indicating that the transfer of ARGs was closely linked to diet, and had some selectivity. Metagenomic results showed that the gut resistance genome could be affected not only by diet, but by exogenous antibiotic resistant bacteria (ARB). Many ARG markers coincided with bacterial markers in diet groups. Therefore, dominant bacteria in different diets are important hosts of ARGs in specific dietary environments, but the many pathogenic bacteria present may cause serious harm to human health.202235030982
739890.9997Spread of chloramphenicol and tetracycline resistance genes by plasmid mobilization in agricultural soil. Spread of antibiotic resistance genes (ARGs) poses a worldwide threat to public health and food safety. However, ARG spread by plasmid mobilization, a broad host range transfer system, in agricultural soil has received little attention. Here, we investigated the spread of chloramphenicol resistance gene (CRG) and tetracycline resistance gene (TRG) in agricultural soil by mobilization of pSUP106 under different conditions, including different concentrations of nutrients, temperatures, soil depths, rhizosphere soils, and soil types. The number of resistant bacteria isolated in non-sterilized soil from the experiments was approximately 10(4) to 10(7) per gram of soil, belonging to 5-10 species from four genera, including nonpathogen, opportunistic pathogen, pathogen bacteria, and gram-positive and gram-negative bacteria, depending on the experiment conditions. In sterilized soil, higher levels of nutrients and higher temperatures promoted plasmid mobilization and ARG expression. Topsoil and deep soil might not support the spread of antibiotic resistance, while ARG dissemination by plasmid mobilization was better supported by maize rhizosphere and loam soils. All these factors might change bacterial growth and the activity of bacteria and lead to the above influence. Introduction of only the donor and helper, or the donor alone also resulted in the transfer of ARGs and large numbers of antibiotic resistant bacteria (ARB), indicating that some indigenous bacteria contain the elements necessary for plasmid mobilization. Our results showed that plasmid mobilization facilitated dissemination of ARGs and ARB in soil, which led to the disturbance of indigenous bacterial communities. It is important to clear ARG dissemination routes and inhibit the spread of ARGs.202031991360
6767100.9997Effects of iron mineral adhesion on bacterial conjugation: Interfering the transmission of antibiotic resistance genes through an interfacial process. Bacterial conjugation is one of the most prominent ways for antibiotic resistance genes (ARGs) transmission in the environment. Interfacial interactions between natural colloidal minerals and bacteria can alter the effective contact of bacteria, thereby affecting ARGs conjugation. Understanding the impact of iron minerals, a core component of colloidal minerals, on ARGs conjugation can help assess and intervene in the risk of ARGs transmission. With three selected iron minerals perturbation experiments, it was found that the conjugative transfer of plasmid that carried kanamycin resistance gene was 1.35 - 3.91-fold promoted by low concentrations of iron minerals (i.e., 5 - 100 mg L(-1)), but inhibited at high concentrations (i.e., 1000 - 2000 mg L(-1)) as 0.10 - 0.22-fold. Conjugation occurrence was highly relevant to the number of bacteria adhering per unit mass of mineral, thus switch in the adhesion modes of mineral-bacterial determined whether the conjugate transfer of ARGs was facilitated or inhibited. In addition, a unified model was formularized upon the physicochemical and physiological effects of adhesion on conjugation, and it can be used in estimating the critical inhibitory concentration of different iron minerals on conjugation. Our findings indicate natural colloidal minerals have great potential for applications in preventing the environmental propagation of ARGs through interfacial interactions.202235472548
6768110.9997Biofilm formation mechanisms of mixed antibiotic-resistant bacteria in water: Bacterial interactions and horizontal transfer of antibiotic-resistant plasmids. Over 95 % of bacteria on water supply pipeline surfaces exist in biofilms, which are hotspots for antibiotic resistance gene (ARG) transmission. This study established mixed biofilm culture systems on a metal iron substrate using Escherichia coli: antibiotic-sensitive bacteria (ASB) and antibiotic-resistant bacteria (ARB). The growth rate and extracellular polymeric substances (EPS) content of mixed biofilm surpassed single-species biofilms due to synergistic interactions among different bacteria. However, the composition of mixed biofilms formed by ASB and ARB became unstable after 72 h, linked to reduced polysaccharide proportions in EPS and inter-bacterial competition. The bacterial composition and conjugative transfer frequency of ARGs in mixed biofilms indicate that biofilm formation significantly enhances horizontal transfer of ARGs. Notably, the conjugative transfer frequency of the mixed biofilm formed by two ARB increased 100-fold within five days. In contrast, the conjugative transfer frequency in the mixed biofilm formed by ASB and ARB was unstable; inter-bacterial competition led to plasmid loss associated with horizontal transfer of ARGs, ultimately resulting in biofilm shedding. Furthermore, genes associated with ARG transfer and biofilm growth up-regulated by 1.5 - 6 and 2 - 7 times, respectively, in mixed biofilm. These findings highlight a mutually reinforcing relationship between biofilm formation and horizontal ARG transmission, with significant environmental implications.202539566460
3856120.9997Food-borne microbes influence conjugative transfer of antimicrobial resistance plasmids in pre-disturbed gut microbiome. Ingestion of antibiotic-resistant bacteria following antibiotic treatments may lead to the transfer of antimicrobial resistance genes (ARGs) within a disturbed gut microbiota. However, it remains unclear whether and how microbes present in food matrices influence ARG transfer. Thus, a previously established mouse model, which demonstrated the conjugative transfer of a multi-drug resistance plasmid (pIncA/C) from Salmonella Heidelberg (donor) to Salmonella Typhimurium (recipient), was used to assess the effects of food-borne microbes derived from fresh carrots on pIncA/C transfer. Mice were pre-treated with ampicillin, streptomycin, sulfamethazine, or left untreated as a control to facilitate bacterial colonization. Contrary to previous findings where high-density colonization of the donor and recipient bacteria occurred in the absence of food-borne microbes, the presence of these microbes resulted in a low abundance of S. Typhimurium and no detection of S. Typhimurium transconjugants in the fecal samples from any of the mice. However, in mice pre-treated with streptomycin, a significant reduction in microbial species richness allowed for the significant enrichment of Enterobacteriaceae and pIncA/C transfer to bacteria from the genera Escherichia, Enterobacter, Citrobacter, and Proteus. These findings suggest that food-borne microbes may enhance ARG dissemination by influencing the population dynamics of bacterial hosts within a pre-disturbed gut microbiome.202540315481
7500130.9997Dead but Not Forgotten: How Extracellular DNA, Moisture, and Space Modulate the Horizontal Transfer of Extracellular Antibiotic Resistance Genes in Soil. Antibiotic-resistant bacteria and the spread of antibiotic resistance genes (ARGs) pose a serious risk to human and veterinary health. While many studies focus on the movement of live antibiotic-resistant bacteria to the environment, it is unclear whether extracellular ARGs (eARGs) from dead cells can transfer to live bacteria to facilitate the evolution of antibiotic resistance in nature. Here, we use eARGs from dead, antibiotic-resistant Pseudomonas stutzeri cells to track the movement of eARGs to live P. stutzeri cells via natural transformation, a mechanism of horizontal gene transfer involving the genomic integration of eARGs. In sterile, antibiotic-free agricultural soil, we manipulated the eARG concentration, soil moisture, and proximity to eARGs. We found that transformation occurred in soils inoculated with just 0.25 μg of eDNA g(-1) soil, indicating that even low concentrations of soil eDNA can facilitate transformation (previous estimates suggested ∼2 to 40 μg eDNA g(-1) soil). When eDNA was increased to 5 μg g(-1) soil, there was a 5-fold increase in the number of antibiotic-resistant P. stutzeri cells. We found that eARGs were transformed under soil moistures typical of terrestrial systems (5 to 30% gravimetric water content) but inhibited at very high soil moistures (>30%). Overall, this work demonstrates that dead bacteria and their eARGs are an overlooked path to antibiotic resistance. More generally, the spread of eARGs in antibiotic-free soil suggests that transformation allows genetic variants to establish in the absence of antibiotic selection and that the soil environment plays a critical role in regulating transformation. IMPORTANCE Bacterial death can release eARGs into the environment. Agricultural soils can contain upwards of 10(9) ARGs g(-1) soil, which may facilitate the movement of eARGs from dead to live bacteria through a mechanism of horizontal gene transfer called natural transformation. Here, we track the spread of eARGs from dead, antibiotic-resistant Pseudomonas stutzeri cells to live antibiotic-susceptible P. stutzeri cells in sterile agricultural soil. Transformation increased with the abundance of eARGs and occurred in soils ranging from 5 to 40% gravimetric soil moisture but was lowest in wet soils (>30%). Transformants appeared in soil after 24 h and persisted for up to 15 days even when eDNA concentrations were only a fraction of those found in field soils. Overall, our results show that natural transformation allows eARGs to spread and persist in antibiotic-free soils and that the biological activity of eDNA after bacterial death makes environmental eARGs a public health concern.202235323025
6765140.9997Environmentally relevant concentrations of triclosan exposure promote the horizontal transfer of antibiotic resistance genes mediated by Edwardsiella piscicida. Aquaculture pathogen and antibiotic resistance genes (ARGs) co-occur in the aquatic environment. Accumulated evidence suggests that aquaculture pathogens can facilitate the horizontal transfer of plasmid-mediated ARGs. However, the role of Edwardsiella piscicida (E. piscicida) in ARG dissemination is still not fully understood. In addition, the potential impact of triclosan (TCS) on the spread of ARGs mediated by E. piscicida is still unknown, so a mating model system was established to investigate the transfer process of ARGs. The results showed that E. piscicida disseminated ARGs on RP4 by horizontal gene transfer (HGT). Furthermore, TCS exposure promoted this process. The conjugative transfer frequencies were enhanced approximately 1.2-1.4-fold by TCS at concentrations from 2 to 20 μg/L, when compared with the control. TCS promoted the HGT of ARGs by stimulating reactive oxygen species (ROS) production, increasing cell membrane permeability, and altering expressions of conjugative transfer-associated genes. Together, the results suggested that aquaculture pathogens spread ARGs and that the emerging contaminant TCS enhanced the transfer of ARGs between bacteria.202235474424
3862150.9996Interaction of tetracycline and copper co-intake in inducing antibiotic resistance genes and potential pathogens in mouse gut. The widespread use of copper and tetracycline as growth promoters in the breeding industry poses a potential threat to environmental health. Nevertheless, to the best of our knowledge, the potential adverse effects of copper and tetracycline on the gut microbiota remain unknown. Herein, mice were fed different concentrations of copper and/or tetracycline for 6 weeks to simulate real life-like exposure in the breeding industry. Following the exposure, antibiotic resistance genes (ARGs), potential pathogens, and other pathogenic factors were analyzed in mouse feces. The co-exposure of copper with tetracycline significantly increased the abundance of ARGs and enriched more potential pathogens in the gut of the co-treated mice. Copper and/or tetracycline exposure increased the abundance of bacteria carrying either ARGs, metal resistance genes, or virulence factors, contributing to the widespread dissemination of potentially harmful genes posing a severe risk to public health. Our study provides insights into the effects of copper and tetracycline exposure on the gut resistome and potential pathogens, and our findings can help reduce the risks associated with antibiotic resistance under the One Health framework.202438527398
3845160.9996A novel microfluidic system enables visualization and analysis of antibiotic resistance gene transfer to activated sludge bacteria in biofilm. Antibiotic resistance genes (ARGs) in environment have become a growing public concern, due to their potential to be obtained by pathogens and their duplication along cell division. Horizontal gene transfer (HGT) was reported to be responsible for ARGs dissemination in microbes, but the HGT feature in environmental biofilm was still unclear due to insufficient assay tools. To address this challenge, we applied a novel microfluidic system to cultivate thin biofilm by continuous supply of nutrients and close contact between cells. Resembling the living state of biofilm in open environment, this chip visualized the transfer of ARG-encoded plasmids RP4 and pKJK5 to the receptors, e.g., activated sludge bacteria. The average plasmid transfer frequency per receptor (T/R) from RP4-hosted Pseudomonas putida KT2440 to activated sludge bacteria was quantified to be 2.5 × 10(-3) via flow cytometry, and T/R for pKJK5-hosted Escherichia coli MG1655 was 8.9 × 10(-3), while the corresponding average frequencies per donor (T/D) were diverse for the two host strains as 4.3 × 10(-3) and 1.4 × 10(-1) respectively. The difference between T/R and T/D was explained by the plasmid transfer kinetics, implying specific purposes of the two calculations. Finally, we collected the transconjugants by fluorescent activated cell sorting and further sequenced their 16S rDNA. Bacteria from phyla Proteobacteria and Firmicutes were found more susceptible to be transconjugants than those from Bacteroidetes. Our work demonstrated that microfluidic system was advantageous in biofilm HGT study, which can provide more insights into environmental ARG control.201829909325
6778170.9996Bisphenol 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
6775180.9996Copper nanoparticles and copper ions promote horizontal transfer of plasmid-mediated multi-antibiotic resistance genes across bacterial genera. The spread of antibiotic resistance has become a major concern for public health. As emerging contaminants, various metallic nanoparticles (NPs) and ionic heavy metals have been ubiquitously detected in various environments. Although previous studies have indicated NPs and ionic heavy metals could exhibit co-selection effects for antibiotic resistance, little is known about whether and how they could promote antibiotic resistance spread via horizontal gene transfer across bacterial genera. This study, we report both CuO NPs and copper ions (Cu(2+)) could stimulate the conjugative transfer of multiple-drug resistance genes. When exposing bacteria to CuO NPs or Cu(2+) at environmental-relevant and sub-inhibitory concentrations (e.g., 1-100 μmol/L), conjugation frequencies of plasmid-encoded antibiotic resistance genes across genera (i.e., from Escherichia coli to Pseudomonas putida) were significantly enhanced (p < 0.05). The over-production of reactive oxygen species played a crucial role in promoting conjugative transfer. Genome-wide RNA and protein sequencing suggested expressional levels of genes and proteins related to oxidative stress, cell membrane permeability, and pilus generation were significantly up-regulated under CuO NPs and Cu(2+) exposure (p < 0.05). This study provides insights in the contributions of NPs and heavy metals on the spread of antibiotic resistance.201931158594
7400190.9996Investigating the effects of municipal and hospital wastewaters on horizontal gene transfer. Horizontal gene transfer (HGT) plays an important role in the dissemination of antibiotic resistance genes. In sewer systems, human-associated and environmental bacteria are mixed together and exposed to many substances known to increase HGT, including various antibacterial compounds. In wastewaters, those substances are most often detected below concentrations known to induce HGT individually. Still, it is possible that such wastewaters induce HGT, for example via mixture effects. Here, a panel of antibiotics, biocides and other pharmaceuticals was measured in filter-sterilized municipal and hospital wastewater samples from Gothenburg, Sweden. The effects on HGT of the chemical mixtures in these samples were investigated by exposing a complex bacterial donor community together with a GFP-tagged E. coli recipient strain. Recipients that captured sulfonamide resistance-conferring mobile genetic elements (MGEs) from the bacterial community were enumerated and characterized by replicon typing, antibiotic susceptibility testing and long read sequencing. While exposure to municipal wastewater did not result in any detectable change in HGT rates, exposure to hospital wastewater was associated with an increase in the proportion of recipients that acquired sulfonamide resistance but also a drastic decrease in the total number of recipients. Although, concentrations were generally higher in hospital than municipal wastewater, none of the measured substances could individually explain the observed effects of hospital wastewater. The great majority of the MGEs captured were IncN plasmids, and resistance to several antibiotics was co-transferred in most cases. Taken together, the data show no evidence that chemicals present in the studied municipal wastewater induce HGT. Still, the increased relative abundance of transconjugants after exposure to hospital wastewater could have implications for the risks of both emergence and transmission of resistant bacteria.202133631686