Bacterial conjugation is a widespread and particularly efficient strategy to horizontally disseminate genes in microbial populations. With a rich and dense population of microorganisms, the ...intestinal microbiota is often considered a fertile environment for conjugative transfer and a major reservoir of antibiotic resistance genes. In this mini-review, we summarize recent findings suggesting that few conjugative plasmid families present in
Enterobacteriaceae
transfer at high rates in the gut microbiota. We discuss the importance of mating pair stabilization as well as additional factors influencing DNA transfer efficiency and conjugative host range in this environment. Finally, we examine the potential repurposing of bacterial conjugation for microbiome editing.
This study reports the characterization of carbapenem-resistant colonizing strains of
.
650 stool samples were screened for carbapenem-resistant
(CR-Kp). All strains were characterized for antibiotic ...susceptibility, typing features, main carbapenemases and extended-spectrum ß-lactamases. The carbapenemase transferability was assessed by interspecific conjugation.
Eighteen CR-Kp were multidrug resistant, five were KPC producing. A predominance of ST307 isolates, constituting the predominant cluster by PFGE analysis, was identified (50% were KPC-2 producers). Conjugation data showed the co-transfer of
KPC-2,
TEM-1,
OXA-1,
CTX-M-15 in a single large pKPN3-like plasmid.
Our data pointed out the diversity of colonizing
strains compared with clinical ones. The predominance of ST307 strains suggested an increased spreading, even in our area, of this high-risk clone.
Carbapenem-resistant
represents a major antibiotic resistance threat worldwide. These microorganisms are associated with high mortality and difficult-to-treat infections. Of particular interest is the production of carbapenemase, enzymes capable of inactivating life-saving drugs such as carbapenems. In the interaction with humans,
plays different roles: commensal, opportunistic pathogen or true pathogen. Our study aimed to analyze the population of
obtained from a fecal screening, since gut-colonizing strains are considered the common source of
nosocomial infections. There are many differences between clinical and colonizing isolates, but the latter are much less characterized. The careful characterization of colonizing strains is crucial, in order to better understand how
may change its role from commensal to pathogen.
Present study characterized five
Escherichia coli
co-expressing ESBL and MCR-1 recovered from food, food-producing animals, and companion animals in China. Antimicrobial susceptibility tests, ...conjugation experiments, and plasmid typing were performed. Whole genome sequencing (WGS) was undertaken for all five isolates using either PacBio RS II or Illumina HiSeq 2500 platforms. The cefotaxime and colistin resistance encoded by
bla
CTX–M
and
mcr-1
genes, respectively, was transferable by conjugation either together or separately for all five strains. Interestingly, the ESBL and
mcr-1
genes could be co-selected by cefotaxime, while the colistin only selected the
mcr-1
-carrying plasmids during the conjugation experiments. Five
E. coli
sequence types (ST88, ST93, ST602, ST162, and ST457) were detected. Although diverse plasmid profiles were identified, IncI2, IncFIB, and IncFII plasmid types were predominant. These five clonally unrelated isolates harbored the
mcr-1
gene located on similar plasmid backbones, which showed high nucleotide similarity to plasmid pHNSHP45. The
mcr-1
gene can be co-transmitted with
bla
CTX–M
genes through IncI2 plasmids with or without IS
Apl1
in our study. Characterization of these co-existence ESBL and mcr-1 isolates extends our understanding on the dissemination of these resistance markers among bacteria of diverse origins.
In this study, five classes of antibiotic resistance genes (ARGs) were quantified in sediment samples of Haihe River, China, with abundance ranging from 1.39 × 104 to 1.58 × 1010 copies/g dry weight. ...Meanwhile, antibiotic resistant conjugative plasmids were also isolated from these samples through filter mating assays. In total, 202 transconjugants were isolated and tested for their antibiotic resistance phenotypes, among which 26 different types of conjugative plasmids were observed. The majority of these plasmids showed a multi-resistant phenotype and the most prevalent resistance was tetracycline resistance and sulfonamide resistance. Furthermore, we tested the transfer frequencies of these plasmids, determined their genotypes and then compared the plasmid-borne ARGs with their corresponding abundance in Haihe River. Most of the isolated plasmids exhibited high transfer frequencies to the recipient strain Escherichia coli J53. Plasmids isolated from the urban areas of Haihe River have higher transfer frequencies than the rural areas. Results from comprehensive analysis of plasmid genotypes, ARG abundance and plasmid sequencing confirmed that most of the plasmid-borne ARGs were the dominant genes in the Haihe River. Therefore, conjugative plasmids isolated from the Haihe River plays a crucial role in the dissemination, abundance and spatial distribution of ARGs in Haihe River, especially some unfrequent ARGs like blaGES-1. This study will help to increase the knowledge on the conjugative plasmid-mediated ARG propagation in the environment.
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•High levels of ARGs were detected in the sediments of Haihe River.•Regional differences were observed between urban areas and rural areas.•Diverse conjugative plasmids including carbapenem resistant plasmid were isolated.•High transfer frequencies of conjugative plasmids were observed.•Conjugative plasmids account for the abundance of ARGs, especially blaGES-1.
By transferring ecologically important traits between species, plasmids drive genomic divergence and evolutionary innovation in their bacterial hosts. Bacterial communities are often diverse and ...contain multiple coexisting plasmids, but the dynamics of plasmids in multi-species communities are poorly understood. Here, we show, using experimental multi-species communities containing two plasmids, that bacterial diversity limits the horizontal transmission of plasmids due to the 'dilution effect'; this is an epidemiological phenomenon whereby living alongside less proficient host species reduces the expected infection risk for a focal host species. In addition, plasmid horizontal transmission was also affected by plasmid diversity, such that the rate of plasmid conjugation was reduced from co-infected host cells carrying both plasmids. In diverse microbial communities, plasmid spread may be limited by the dilution effect and plasmid-plasmid interactions, reducing the rate of horizontal transmission.
Wastewater treatment plants (WWTPs) are recognized as hotspots for horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). Despite our understanding of the composition and distribution ...of ARGs in WWTPs, the genetic location, host, and fate of ARGs remain largely unknown.
In this study, we combined Oxford Nanopore and Illumina metagenomics sequencing to comprehensively uncover the resistome context of influent, activated sludge, and effluent of three WWTPs and simultaneously track the hosts of the ARGs. The results showed that most of the ARGs detected in all compartments of the WWTPs were carried by plasmids. Transposons and integrons also showed higher prevalence on plasmids than on the ARG-carrying chromosome. Notably, integrative and conjugative elements (ICEs) carrying five types of ARGs were detected, and they may play an important role in facilitating the transfer of ARGs, particularly for tetracycline and macrolide-lincosamide-streptogramin (MLS). A broad spectrum of ARGs carried by plasmids (29 subtypes) and ICEs (4 subtypes) was persistent across the WWTPs. Host tracking showed a variety of antibiotic-resistant bacteria in the effluent, suggesting the high potential for their dissemination into receiving environments. Importantly, phenotype-genotype analysis confirmed the significant role of conjugative plasmids in facilitating the survival and persistence of multidrug-resistant bacteria in the WWTPs. At last, the consistency in the quantitative results for major ARGs types revealed by Nanopore and Illumina sequencing platforms demonstrated the feasibility of Nanopore sequencing for resistome quantification.
Overall, these findings substantially expand our current knowledge of resistome in WWTPs, and help establish a baseline analysis framework to study ARGs in the environment.
Microbial electrochemical systems have gained much attention over the past decade due to their potential for various environmental engineering applications ranging from energy production to ...wastewater treatment to bioproduction. At the heart of these systems lie exoelectrogens–microorganisms capable of exporting electrons generated during metabolism to external electron acceptors such as electrodes. The bacterial biofilm communities on these electrodes are dominated by exoelectrogens but are nonetheless extremely diverse. So far, within the field, the main focus has been on the electroactive bacteria. However, to broaden our understanding of these communities, it is crucial to clarify how the remaining inhabitants of electrode-respiring biofilms contribute to the overall function of the biofilm. Ultimately, such insights may enable improvement of microbial electrochemical systems by reshaping the community structure with naturally occurring beneficial strains.
Conjugative plasmids are mobile elements that spread horizontally between bacterial hosts and often confer adaptive phenotypes, including antimicrobial resistance (AMR). Theory suggests that ...opportunities for horizontal transmission favor plasmids with higher transfer rates, whereas selection for plasmid carriage favors less-mobile plasmids. However, little is known about the mechanisms leading to variation in transmission rates in natural plasmids or the resultant effects on their bacterial host. We investigated the evolution of AMR plasmids confronted with different immigration rates of susceptible hosts. Plasmid RP4 did not evolve in response to the manipulations, but plasmid R1 rapidly evolved up to 1,000-fold increased transfer rates in the presence of susceptible hosts. Most evolved plasmids also conferred on their hosts the ability to grow at high concentrations of antibiotics. This was because plasmids evolved greater copy numbers as a function of mutations in the
gene controlling plasmid replication, causing both higher transfer rates and AMR. Reciprocally, plasmids with increased conjugation rates also evolved when selecting for high levels of AMR, despite the absence of susceptible hosts. Such correlated selection between plasmid transfer and AMR could increase the spread of AMR within populations and communities.
Conjugative plasmids: vessels of the communal gene pool Norman, Anders; Hansen, Lars H.; Sørensen, Søren J.
Philosophical transactions - Royal Society. Biological sciences,
08/2009, Letnik:
364, Številka:
1527
Journal Article
Recenzirano
Odprti dostop
Comparative whole-genome analyses have demonstrated that horizontal gene transfer (HGT) provides a significant contribution to prokaryotic genome innovation. The evolution of specific prokaryotes is ...therefore tightly linked to the environment in which they live and the communal pool of genes available within that environment. Here we use the term supergenome to describe the set of all genes that a prokaryotic 'individual' can draw on within a particular environmental setting. Conjugative plasmids can be considered particularly successful entities within the communal pool, which have enabled HGT over large taxonomic distances. These plasmids are collections of discrete regions of genes that function as 'backbone modules' to undertake different aspects of overall plasmid maintenance and propagation. Conjugative plasmids often carry suites of 'accessory elements' that contribute adaptive traits to the hosts and, potentially, other resident prokaryotes within specific environmental niches. Insight into the evolution of plasmid modules therefore contributes to our knowledge of gene dissemination and evolution within prokaryotic communities. This communal pool provides the prokaryotes with an important mechanistic framework for obtaining adaptability and functional diversity that alleviates the need for large genomes of specialized 'private genes'.
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