Chryseobacterium tructae sp. nov., isolated from rainbow trout (Oncorhynchus mykiss)

Abstract

Three pale-orange bacteria (strains 1083-08, 1084-08(T) and 1095B-08) were isolated from diseased rainbow trout. The isolates were Gram-staining-negative, catalase- and oxidase-positive, rod-shaped cells. Analyses of their 16S rRNA gene sequences confirmed their adscription to the genus Chryseobacterium. The three isolates shared 100% 16S rRNA gene sequence similarity and 98.5% similarity with Chryseobacterium indologenes CCUG 14556(T), being the closest phylogenetically related species. Genomic DNA-DNA hybridization similarity values between the three isolates were 94-100% and 2-39% between strain 1084-08(T) and the type strains of other related Chryseobacterium species, confirming that the isolates represent a novel species within the genus Chryseobacterium. The DNA G+C content of the species was 33.6-36.1mol%. The predominant respiratory quinone of strain 1084-08(T) was MK-6 and the major fatty acids were iso-C(15:0), iso-C(17:1)ω9c, iso-C(17:0) 3-OH and C(16:1)ω6c. The isolates were distinguished from related Chryseobacterium species by a number of phenotypic properties. Based on the phenotypic, genotypic and phylogenetic findings, it is proposed that the new isolates from rainbow trout be classified as a new species of the genus Chryseobacterium, with the name of Chryseobacterium tructae sp. nov. The type strain is 1084-08(T) (=CECT 7798(T)=CCUG 60111(T)).