Marcoux Pierre-Étienne, Attéré Sabrina A, Paquet Valérie E, Paquet Maude F, Girard Sarah B, Farley Judith, Frenette Michel, Vincent Antony T, Charette Steve J
Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada.
Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada.
Antibiotics (Basel). 2023 Jan 27;12(2):257. doi: 10.3390/antibiotics12020257.
Plasmids that carry antibiotic resistance genes occur frequently in subsp. , an aquatic pathogen with severe consequences in salmonid farming. Here, we describe a 67 kb plasmid found in the subsp. Strain SHY15-2939 from Quebec, Canada. This new plasmid, named pAsa-2939 and identified by high throughput sequencing, displays features never found before in this bacterial species. It contains a transposon related to the Tn family, but with an unusual organization. This transposon bears a gene (chloramphenicol resistance) that has not been detected yet in subsp. . The plasmid is transferable by conjugation into , but not into . Based on PCR analysis and genomic sequencing (Illumina and PacBio), we determined that the transposon is unstable in subsp. Strain SHY15-2939, but it is stable in trans-conjugants, which explains the chloramphenicol resistance variability observed in SHY15-2939. These results suggest that this bacterium is likely not the most appropriate host for this plasmid. The presence of pAsa-2939 in subsp. also strengthens the reservoir role of this bacterium for antibiotic resistance genes, even those that resist antibiotics not used in aquaculture in Québec, such as chloramphenicol.
携带抗生素抗性基因的质粒在亚种中频繁出现，该亚种是一种水生病原体，在鲑鱼养殖中会造成严重后果。在此，我们描述了在来自加拿大魁北克的亚种菌株SHY15 - 2939中发现的一个67 kb质粒。这个名为pAsa - 2939的新质粒通过高通量测序鉴定，展现出该细菌物种中从未发现过的特征。它包含一个与Tn家族相关的转座子，但结构不同寻常。这个转座子带有一个基因（氯霉素抗性），在亚种中尚未检测到。该质粒可通过接合转移到中，但不能转移到中。基于PCR分析和基因组测序（Illumina和PacBio），我们确定该转座子在亚种菌株SHY15 - 2939中不稳定，但在转接合子中稳定，这解释了在SHY15 - 2939中观察到的氯霉素抗性变异性。这些结果表明，这种细菌可能不是该质粒最合适的宿主。亚种中pAsa - 2939的存在也强化了这种细菌作为抗生素抗性基因储存库的作用，即使是那些对魁北克水产养殖中未使用的抗生素（如氯霉素）具有抗性的基因。
