Abstrait

Isolation and identification of Citrobacter spp. from the intestine of Procambarus clarkii.

Honglian Chen, Yongjie Wang*, Jing Zhang, Yunsheng Chen, Minglin Wu

Citrobacter have caused a wide spectrum of infectious diseases in aquaculture animals and human. In previous study, pathogenic Citrobacter spp. was frequently isolated from hepatopancreas of diseased Procambarus clarkii. It suggested that the intestine might be the reservoirs of Citrobacter spp. Intestinal flora were isolated from P. clarkii with Salmonella shigella agar. 126 isolates were performed with enterobacterial repetitive intergenic consensus (ERIC) PCR. 95 strains of seven ERIC-PCR electrophoretic genotypes were identified as Citrobacter spp. by 16S rRNA gene sequence analysis and the urease gene detection of the representative strains. Eight representative strains were defined by biochemical characteristics and multilocus sequence analysis of genes fusA, leuS, rpoB and pyrG. Isolates 425C1, 731C1 and 519C4 were determined as C. freundii, C. werkmanii and a new species of C. freundii complex, respectively. Isolates 425C3, 519C1, 519C3, 519C41 and 519C53 were identified as C. braakii. C. freundii strain 425C1 and C. werkmanii strain 731C1 were verified pathogenic bacteria to P. clarkii and Kunming mice in varying degrees. To our knowledge, this is the first report of pathogenic C. werkmanii.