f Nocardia seriolae sp. nov. Causing Nocardiosis of Cultured Fish

Five strains of bacteria causing nocardiosis in cultured fishes (yellowtails [Seriola quinqueradiata] and Japanese flounder [Paralichthys olivaceus]) were studied to establish their taxonomic status. Well-developed fragmenting vegetative mycelium was observed. The chemotype was type IVA containing meso-diaminopimelic acid, arabinose, and galactose. The predominant isoprenoid quinone was MK-8(H4), and mycolic acids were present. These morphological and chemical properties are characteristic of the genus Nocardia. The physiological and biochemical characteristics were most similar to those of Nocardia asteroides; however, these organisms were different in their decomposition of urea, growth temperature, utilization of nitrogen sources, survival at 50°C for 8 h, mycolic and fatty acid profiles, and deoxyribonucleic acid-deoxyribonucleic acid hybridization characteristics. Therefore, we propose a new species for these strains, Nocardia seriolae. The type strain is strain JCM 3360.