Similarity in the Structure of tetD-Carrying Mobile Genetic Elements in Bacterial Strains of Different Genera Isolated from Cultured Yellowtail

摘要

Structure analysis was performed on the antibiotic-resistance-gene region of conjugative plasmids of four fish farm bacteria.The kanamycin resistance gene, IS26 , and tetracycline resistance gene (tetA (D )) were flanked by two IS26 s in opposite orientation in Citrobacter sp. TA3 and TA6, and Alteromonas sp. TA55 from fish farm A. IS26 -Inner was disrupted with ISRSB101 . The chloramphenicol resistance gene, IS26 and tetA (D ) were flanked by two IS26 s in direct orientation in Salmonella sp. TC67 from farm C. Structures of tetA (D ) and IS26 were identical among the four bacteria, but there was no insertion within the IS26 -Inner of Salmonella sp. TC67. Horizontal gene transfer between the strains of two different genera in fish farm A was suggested by the structure homologies of mobile genetic elements and antibiotic resistance genes.