Abstract
Five strains (1126-1H-08T, 51B-09, 986-08, 1084B-08 and 424-08) were isolated from diseased rainbow trout. Cells were Gram-negative rods, 0.7 µm wide and 3 µm long, non-endospore-forming, catalase and oxidase positive. Colonies were circular, yellow-pigmented, smooth and entire on TGE agar after 72 hours incubation at 25°C. They grew in a temperature range between 15°C to 30°C, but they did not grow at 37°Cor 42°C. Based on 16S rRNA gene sequence analysis, the isolates belonged to the genus Flavobacterium. Strain 1126-1H-08T exhibited the highest levels of similarity with Flavobacterium oncorhynchi CECT 7678T and Flavobacterium pectinovorum DSM 6368T (98.5% and 97.9% sequence similarity, respectively). DNA–DNA hybridization values were 87 to 99% among the five isolates and ranged from 21 to 48% between strain 1126-1H-08T, selected as a representative isolate, and the type strains of Flavobacterium oncorhynchi CECT 7678T and other phylogenetic related Flavobacterium species. The DNA G+C content of strain 1126-1H-08T was 33.2 mol%. The predominant respiratory quinone was MK-6 and the major fatty acids were iso-C15∶0 and C15∶0. These data were similar to those reported for Flavobacterium species. Several physiological and biochemical tests differentiated the novel bacterial strains from related Flavobacterium species. Phylogenetic, genetic and phenotypic data indicate that these strains represent a new species of the genus Flavobacterium, for which the name Flavobacterium plurextorum sp. nov. was proposed. The type strain is 1126-1H-08T ( = CECT 7844T = CCUG 60112T).
Highlights
The genus Flavobacterium is the type genus of the family Flavobacteriaceae accommodating Gram-negative, non-endosporeforming, aerobic, oxidase-positive, non-fermenting, predominantly gliding, yellow-pigmented bacteria [1,2]
Some Flavobacterium species, mainly Flavobacterium columnare, Flavobacterium branchiophilum and Flavobacterium psychrophilum, are wellrecognized fish pathogens responsible for important economic losses in the fish farming industry [6,7]. Several other species such as Flavobacterium hydatis, Flavobacterium jhonsoniae, Flavobacterium succinicans, Flavobacterium chilense, Flavobacterium araucananum or Flavobacterium oncorhynchi have been associated with infections in fish [1,4,5,8,9,10]
We report the phenotypic, genotypic and phylogenetic characterization of five novel Flavobacterium-like strains isolated from diseased trout
Summary
The genus Flavobacterium is the type genus of the family Flavobacteriaceae accommodating Gram-negative, non-endosporeforming, aerobic, oxidase-positive, non-fermenting, predominantly gliding, yellow-pigmented bacteria [1,2]. A number of new Flavobacterium species have been described from the water of aquaculture facilities [11,12,13] This plethora of Flavobacterium species could reproduce the diversity of flavobacteria associated with fish or fish surrounding environments. Some of these species could be considered commensal and opportunistic pathogenic bacteria [4], which point out the necessity for an accurate identifications of those strains of Flavobacterium spp. isolated from fish or fish farm environments. Such identifications are extremely difficult based exclusively on biochemical criteria [4,8,14] and must be complemented with chemotaxomic and genetic methods [4,5]
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