Identification of bacterial plasmids based on mobility and plasmid population biology

Abstract

Plasmids contain a backbone of core genes that remains relatively stable for long evolutionary periods, making sense to speak about plasmid species. The identification and characterization of the core genes of a plasmid species has a special relevance in the study of its epidemiology and modes of transmission. Besides, this knowledge will help to unveil the main routes that genes, for example antibiotic resistance (AbR) genes, use to travel from environmental reservoirs to human pathogens. Global dissemination of multiple antibiotic resistances and virulence traits by plasmids is an increasing threat for the treatment of many bacterial infectious diseases. To follow the dissemination of virulence and AbR genes, we need to identify the causative plasmids and follow their path from reservoirs to pathogens. In this review, we discuss how the existing diversity in plasmid genetic structures gives rise to a large diversity in propagation strategies. We would like to propose that, using an identification methodology based on plasmid mobility types, we can follow the propagation routes of most plasmids in Gammaproteobacteria, as well as their cargo genes, in complex ecosystems. Once the dissemination routes are known, designing antidissemination drugs and testing their efficacy will become feasible. We discuss in this review how the existing diversity in plasmid genetic structures gives rise to a large diversity in propagation strategies. We would like to propose that, by using an identification methodology based on plasmid mobility types, we can follow the propagation routes of most plasmids in ?-proteobacteria, as well as their cargo genes, in complex ecosystems.

Recovery of Plasmid pEMB1, Whose Toxin-Antitoxin System Stabilizes an Ampicillin Resistance-Conferring β-Lactamase Gene in Escherichia coli, from Natural Environments

“…In particular, plasmids may play important roles as mobile genetic elements that can disseminate antibiotic resistance genes to clinically relevant pathogenic bacteria (18,19). Surprisingly, some recent studies have shown that antibiotic resistance genes encoded by plasmids were stably maintained in the absence of selective pressures (20)(21)(22); however, in these studies, the mechanisms of plasmid maintenance were not suggested.…”

pA506, a Conjugative Plasmid of the Plant Epiphyte Pseudomonas fluorescens A506

“…Large plasmids (exceeding 30 kb in size), such as pA506, are typically maintained at low copy number in the bacterial cell (54). Such low-copy-number plasmids depend on partitioning systems to ensure their stable inheritance by daughter bacterial cells.…”

Conjugative transmission of antibiotic-resistance from stream waterEscherichia colias related to number of sulfamethoxazole but not class 1 and 2 integrase genes

“…7 An example of this plasmid is the AbR IncW plasmid R388 of Enterobacteriaceae. 8 Mobilizable plasmids, on the other hand, contain only a minimal set of genes that allow them to be mobilized by conjugation when they coexist in the same donor cell with a conjugative plasmid. These non-self-transmissible plasmids carry only the MOB module, and their transfer requires an MPF provided by another genetic element.…”

“…7 An example of a mobilizable plasmid is the IncQ1 plasmid RSF1010. 8 Integrons are not self-mobilizing genetic elements; however, previous research has indicated the likelihood of resistance to multiple antibiotics associated with integrons, 9 and resistance to multiple antibiotics, integrons, and promiscuous plasmids co-occurring in wastewater treatment effluent. 10 An integron is a bacterial genetic element containing a site-specific recombination system that is able to efficiently acquire, rearrange, and express genes embedded within a gene cassette (GC).…”