Project description:Antibiotic resistance is exacerbated by the exchange of antibiotic resistance genes (ARGs) between microbes from diverse habitats. Plasmids are important ARGs mobile elements and are spread by horizontal gene transfer (HGT). In this study, we demonstrated the presence of multi-resistant plasmids from inhalable particulate matter (PM) and its effect on gene horizontal transfer. Three transferable multi-resistant plasmids were identified from PM in a hospital, using conjugative mating assays and nanopore sequencing. pTAir-3 contained 26 horizontal transfer elements and 10 ARGs. Importantly pTAir-5 harbored carbapenem resistance gene (blaOXA) which shows homology to plasmids from human and pig commensal bacteria, thus indicating that PM is a media for antibiotic resistant plasmid spread. In addition, 125 μg/mL PM2.5 and PM10 significantly increased the conjugative transfer rate by 110% and 30%, respectively, and augmented reactive oxygen species (ROS) levels. Underlying mechanisms were revealed by identifying the upregulated expressional levels of genes related to ROS, SOS, cell membranes, pilus generation, and transposition via genome-wide RNA sequencing. The study highlights the airborne spread of multi-resistant plasmids and the impact of inhalable PM on the horizontal transfer of antibiotic resistance.
Project description:<p>The study of antimicrobial resistance (AMR) in infectious diarrhea has generally been limited to cultivation, antimicrobial susceptibility testing and targeted PCR assays. When individual strains of significance are identified, whole genome shotgun (WGS) sequencing of important clones and clades is performed. Genes that encode resistance to antibiotics have been detected in environmental, insect, human and animal metagenomes and are known as "resistomes". While metagenomic datasets have been mined to characterize the healthy human gut resistome in the Human Microbiome Project and MetaHIT and in a Yanomani Amerindian cohort, directed metagenomic sequencing has not been used to examine the epidemiology of AMR. Especially in developing countries where sanitation is poor, diarrhea and enteric pathogens likely serve to disseminate antibiotic resistance elements of clinical significance. Unregulated use of antibiotics further exacerbates the problem by selection for acquisition of resistance. This is exemplified by recent reports of multiple antibiotic resistance in Shigella strains in India, in Escherichia coli in India and Pakistan, and in nontyphoidal Salmonella (NTS) in South-East Asia. We propose to use deep metagenomic sequencing and genome level assembly to study the epidemiology of AMR in stools of children suffering from diarrhea. Here the epidemiology component will be surveillance and analysis of the microbial composition (to the bacterial species/strain level where possible) and its constituent antimicrobial resistance genetic elements (such as plasmids, integrons, transposons and other mobile genetic elements, or MGEs) in samples from a cohort where diarrhea is prevalent and antibiotic exposure is endemic. The goal will be to assess whether consortia of specific mobile antimicrobial resistance elements associate with species/strains and whether their presence is enhanced or amplified in diarrheal microbiomes and in the presence of antibiotic exposure. This work could potentially identify clonal complexes of organisms and MGEs with enhanced resistance and the potential to transfer this resistance to other enteric pathogens.</p> <p>We have performed WGS, metagenomic assembly and gene/protein mapping to examine and characterize the types of AMR genes and transfer elements (transposons, integrons, bacteriophage, plasmids) and their distribution in bacterial species and strains assembled from DNA isolated from diarrheal and non-diarrheal stools. The samples were acquired from a cohort of pediatric patients and controls from Colombia, South America where antibiotic use is prevalent. As a control, the distribution and abundance of AMR genes can be compared to published studies where resistome gene lists from healthy cohort sequences were compiled. Our approach is more epidemiologic in nature, as we plan to identify and catalogue antimicrobial elements on MGEs capable of spread through a local population and further we will, where possible, link mobile antimicrobial resistance elements with specific strains within the population.</p>
Project description:Integrative and conjugative elements (ICEs), a.k.a., conjugative transposons, are mobile genetic elements involved in many biological processes, including the spread of antibiotic resistance. Unlike conjugative plasmids that are extra-chromosomal and replicate autonomously, ICEs are integrated in the chromosome and replicate passively during chromosomal replication. It is generally thought that ICEs do not replicate autonomously. We found that when induced, Bacillus subtilis ICEBs1 replicates as a plasmid. The ICEBs1 origin of transfer (oriT) served as the origin of replication and the conjugal DNA relaxase served as the replication initiation protein. Autonomous replication of ICEBs1 conferred genetic stability to the excised element, but was not required for mating. The B. subtilis helicase PcrA that mediates unwinding and replication of Gram-positive rolling circle replicating plasmids was required for ICEBs1 replication and mating. Nicking of oriT by the relaxase and unwinding by PcrA likely directs transfer of a single-strand of ICEBs1 into recipient cells. This SuperSeries is composed of the SubSeries listed below.
Project description:Tn insertion library was used for recipient for conjugative transfer of pESBL, F, and R388 plasmids. For both recipient and the resulting exconjugant libraries, Tn insertion sites were determined by illumina sequencing
Project description:Rhizobia are gram-negative bacteria able to establish a symbiotic interaction with leguminous plants. Due to their nitrogen fixing capacity, the study of these microorganisms has acquired great relevance for the agriculture. Rhizobia usually harbor many plasmids in their genome which can be transferred to other organisms by conjugation. Two main mechanisms of regulation of rhizobial plasmid transfer have been described: Quorum sensing (QS) and rctA/rctB system. Nevertheless, new genes and molecules that modulate conjugative transfer have been recently described, demonstrating that new actors can tightly regulate the process. In this work, by means of bioinformatics tools and molecular biology approaches, two hypothetical genes are identified as playing key roles in conjugative transfer. These genes are located between conjugative genes of plasmid pLPU83a from Rhizobium favelukesii LPU83, a plasmid that showed a conjugative transfer behavior depending on the genomic background. One of the two mentioned genes, rcgA, is essential for conjugation, while the other, rcgR, acts as an inhibitor of the process. In addition to introducing this new regulatory mechanism, we show evidence of the functions of these genes in different genomic backgrounds, and confirmed that homologous proteins from non-closely related organisms play the same function. These findings set up a cornerstone for a new molecular circuit of conjugative transfer of plasmids.
Project description:RctR encodes a protein belonging to the GntR family of transcriptional regulators and is involved in regulation of conjugative transfer of symbiotic plasmids of Sinorhizobium meliloti. In order to identify genes differentially expressed in a 1021RctR mutant, the transcriptome of S. meliloti 1021RctR was compared with that of the wild-type 1021, using Sm6kOligo DNA microarrays. Cells of 1021 and 1021RctR were grown at 30C in TY broth to mid logarothmic phase (OD600nm)=0.7-0.8 before RNA isolation.
Project description:we examined the three different mature biofilms and searched the genes which promoted the rapid biofilm formation when their population hosing the plasmids. We investigate the global transcriptional differences between the non-conjugative or conjugative plasmid-carrying and plasmid-free strains.
Project description:Conjugative plasmids are the main vehicle for the horizontal spread of antimicrobial resistance (AMR). Although AMR plasmids provide advantages to their hosts under antibiotic pressure, they can also disrupt the cell’s regulatory network, impacting the fitness of their hosts. Despite the importance of plasmid-bacteria interactions on the evolution of AMR, the effects of plasmid carriage on host physiology has remained underexplored, and most studies have focused on model bacteria and plasmids that lack clinical relevance. Here, we analyzed the transcriptional response of 11 clinical enterobacterial strains (2 Escherichia coli, 1 Citrobacter freundii and 8 Klebsiella spp.) and the laboratory-adapted E. coli MG1655 to carriage of pOXA-48, one of the most widely spread carbapenem-resistance plasmids. Our analyses revealed that pOXA-48 produces variable responses on their hosts, but commonly affects processes related to metabolism, transport, response to stimulus, cellular organization and motility. More notably, the presence of pOXA-48 caused an increase in the expression of a small chromosomal operon of unknown function in Klebsiella spp. and C. freundii, which is not present in E. coli. Phylogenetic analysis suggested that this operon has been horizontally mobilized across different Proteobacteria species. We demonstrate that a pOXA-48-encoded LysR transcriptional regulator controls the expression of the operon in Klebsiella spp. and C. freundii. In summary, our results highlight a crosstalk between pOXA-48 and the chromosome of its natural hosts.