Genomic and Transcriptomic Analyses Reveal Multiple Strategies for to Tolerate Sub-Lethal Concentrations of Three Antibiotics.

can cause acute gastroenteritis, wound infections, and septicemia in humans. The overuse of antibiotics in aquaculture may lead to a high incidence of the multidrug-resistant (MDR) pathogen. Nevertheless, the genome evolution of in aquatic animals and the mechanism of its antibiotic tolerance remain to be further deciphered. Here, we investigated the molecular basis of the antibiotic tolerance of isolates ( = 3) originated from shellfish and crustaceans using comparative genomic and transcriptomic analyses. The genome sequences of the isolates were determined (5.0-5.3 Mb), and they contained 4709-5610 predicted protein-encoding genes, of which 823-1099 genes were of unknown functions. Comparative genomic analyses revealed a number of mobile genetic elements (MGEs, = 69), antibiotic resistance-related genes ( = 7-9), and heavy metal tolerance-related genes ( = 2-4). The isolates were resistant to sub-lethal concentrations (sub-LCs) of ampicillin (AMP, 512 μg/mL), kanamycin (KAN, 64 μg/mL), and streptomycin (STR, 16 μg/mL) ( < 0.05). Comparative transcriptomic analyses revealed that there were significantly altered metabolic pathways elicited by the sub-LCs of the antibiotics ( < 0.05), suggesting the existence of multiple strategies for antibiotic tolerance in . The results of this study enriched the genome database and should be useful for controlling the MDR pathogen worldwide.