Nocardiosis is a commercially important disease in cultured largemouth bass in China

causing substantial economic losses. However

the pathogen causing largemouth bass nocardiosis has not yet been isolated in China. In this study

a strain of

Nocardia

(designed as NH090627) was isolated from diseased largemouth bass reared in Nanhai

Guangdong. The bacteria appeared Grampositive

beadlike or long

slender

filamentous rods in shapes. The traditional physiological and biochemical methods showed that most of the phenotypes of strain NH090627 were similar to

Nocardia

. Phylogeny analysis with 16S rDNA showed that the strain NH090627 was branched into the same cluster as that of other species of

Nocardia

and had a higher identity with

Nocardia seriolae

JCM 3360

T

(99.9%). Based on morphological

physiological

biochemical properties and phylogenetic analysis

the filamentous rod bacterial was identified as

Nocardia seriolae.

Antimicrobial susceptibility assay showed that this strain was susceptible to chloramphenicol

streptomycin

kanamycin and tetracycline

but high resistant to sulphamethoxazole and ampicillin.