Characterization of a Mycobacterium sp. isolated from guppy poecilia reticulata, using 16S ribosomal RNA and its internal transcribed spacer sequences

Heavy mortalities were observed in many guppy (Poecilia reticulate) farms, in the vicinity of Bangkok. Two strains of Mycobacterium were isolated in pure cultures from spleen and liver of diseased guppies and the 16S ribosomal RNA and 16S-23S internal transcribed spacer (ITS-1) sequences for these isolates were determined. Phylogenetic analysis, based on the 16S rRNA and ITS-1 sequences of isolated bacteria indicated them to be closely related to Mycobacterium gordonae with homology of approximately 98%. These findings suggest that the Mycobacterium strains causing heavy mortalities in the commercial fish farms can be presumptively assigned to Mycobacterium gordonae.