Detection of a New Mycobacterium Species in Wild Striped Bass in the Chesapeake Bay

摘要

Investigation into recent declines in striped bass health in the Chesapeake Bay in Maryland resulted in the isolation of a putative new species of Mycobacterium. This isolate was obtained from fish showing skin ulcers and internal granulomas in various organs. The isolate was slow growing at 28°C; was nonchromogenic; showed no activities of nitrate reduction, catalase activity, Tween 80 hydrolysis, tellurite reduction, or arylsulfatase reduction; grew best at low salt concentrations; and was urease and pyrazinamidase positive. By PCR a unique insertional sequence was identified which matched nothing in any database. Analysis of the nearly complete 16S rRNA gene sequence also indicated a unique sequence which had 87.7% sequence homology to Mycobacterium ulcerans, 87.6% homology to Mycobacterium tuberculosis, and 85.9% homology to Mycobacterium marinum. Phylogenetic analysis placed the organism close to the tuberculosis complex. These data support the conclusion that the isolate probably represents a new mycobacterial species.