Genome Sequence of Listeria monocytogenes Plasmid pLM-C-273 Carrying Genes Related to Stress Resistance

Abstract

Mobile genetic elements in bacteria, such as plasmids, act as important vectors for the transfer of antibiotic resistance, virulence, and metal resistance genes. Here, we report the genome sequence of a new plasmid pLM-C-273, identified in a Listeria monocytogenes strain isolated from a clinical sample in Ontario, Canada.

Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions

“…The G + C contents of the two plasmid groups also differed slightly with G1 plasmids containing 34.4–36.9% GC, and G2 plasmids having slightly higher GC levels of 36.6–37.7%. Despite the slight differences, all GC levels align with those previously reported for L. monocytogenes plasmids [17,32] and genomes (37–38% GC) [33], as well as the genomes of other firmicutes such as Lactobacillus , Staphylococcus , and Clostridium species [34]. A Blastn search of all plasmid contigs only revealed similarities to other Listeria spp.…”

“…To date, plasmids acquired by L. monocytogenes have been shown to contain genes that confer resistance to sanitizers [11,12,13], heavy metals [7,12,13], and to a range of common antibiotics, including chloramphenicol, clindamycin, erythromycin, streptomycin and tetracycline [14,15]. Additionally, genes associated with oxidative, osmotic, and heat stress have also been observed in L. monocytogenes plasmids [16,17,18].…”

New Aspects on Listeria monocytogenes ST5-ECVI Predominance in a Heavily Contaminated Cheese Processing Environment

“…A striking result was that L. monocytogenes ST5 (genetic lineage I; 1/2b, 3b) and ST204 strains (genetic lineage II; 1/2a, 3a) shared the same plasmids and additionally possessed SSI-1 for acid and salt adaptation. The occurrence of virtually identical plasmids in L. monocytogenes strains from various years and environments described here and in other recent studies strongly suggests the importance of plasmids for the survival of L. monocytogenes strains in various FPE ( Fox et al, 2016 ; Liang et al, 2016 ; Xu et al, 2016 ; Hingston et al, 2017 ; Meier et al, 2017 ). More research will be needed in the future to determine the contribution of these plasmids to survival in FPE.…”

“…The high similarity of the ST5 and ST204 plasmids in strains from the FPE, suggests that the plasmids might have been transferred from the ST5 strains to the ST204 strains which occurred in the FPE in 2012 and became more abundant in 2013 (data not shown). Alternatively, the presence of almost identical plasmids (pLM80 prototypes) in different CC (5, 6, 9, 121, 204) and serotypes (1/2b, 4b) which are globally spread, suggests that a high selective pressure acts on these plasmids and they probably confer additional stress response capabilities to their host strains ( Fox et al, 2016 ; Liang et al, 2016 ; Xu et al, 2016 ; Hingston et al, 2017 ; Meier et al, 2017 ). Our findings are in line with recent studies suggesting that the presence of almost identical plasmids in strains from different geographic sources and years suggests important contribution of plasmids to survival in food and FPEs ( Schmitz-Esser et al, 2015 ; Fagerlund et al, 2016 ; Fox et al, 2016 ).…”

“…So-called persistent L. monocytogenes strains were reported to be better environmentally adapted due to the presence of resistance markers on plasmids (e.g., plasmid group1: plM33; group 2: plMST6; plM5578, plM80; pLM6179), the presence of prophages (tRNA, comK , phiLMST6), premature stop codons in inlA , stress-survival islet 1 (SSI-1; in ST3, 7, 8, 9, 155, and 204) or SSI-2 (CC121), enhanced biofilm formation, and/or tolerance to disinfectants as benzalkonium chloride (BC) ( Elhanafi et al, 2010 ; Lomonaco et al, 2013 ; Müller et al, 2013 ; Melo et al, 2015 ; Liang et al, 2016 ; Martínez-Suárez et al, 2016 ; Xu et al, 2016 ; Buchanan et al, 2017 ; Hingston et al, 2017 ; Knudsen et al, 2017 ; Kremer et al, 2017 ).…”