ABSTRACT
Abstract Yellow pigmented, filamentous, Gram-negative bacteria belonging to genus Flavobacterium are commonly associated with infections in stressed fish. In this study, inter-species diversity of Flavobacterium was studied in apparently healthy freshwater farmed fishes. For this, ninety one yellow pigmented bacteria were isolated from skin and gill samples (n = 38) of three farmed fish species i.e. Labeo rohita, Catla catla and Cyprinus carpio. Among them, only twelve bacterial isolates (13.18%) were identified as Flavobacterium spp. on the basis of morphological, biochemical tests, partial 16S rDNA gene sequencing and phylogenetic analysis. On the basis of 16S rDNA gene sequencing, all the 12 isolates were 97.6-100% similar to six different formally described species of genus Flavobacterium. The 16S rDNA based phylogenetic analysis grouped these strains into six different clades. Of the 12 isolates, six strains (Fl9S1-6) grouped with F. suncheonense, two strains (Fl6I2, Fl6I3) with F. indicum and the rest four strains (Fl1A1, Fl2G1, Fl3H1 and Fl10T1) clustered with F. aquaticum, F. granuli, F. hercynium and F. terrae, respectively. None of these species except, F. hercynium were previously reported from fish. All the isolated Flavobacterium species possessed the ability of adhesion and biofilm formation to colonize the external surface of healthy fish. The present study is the first record of tropical freshwater farmed fishes as hosts to five environmentally associated species of the Flavobacterium.
Subject(s)
Animals/classification , Animals/genetics , Animals/isolation & purification , Animals/microbiology , Animals/physiology , Animals/veterinary , DNA, Bacterial/classification , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , DNA, Bacterial/microbiology , DNA, Bacterial/physiology , DNA, Bacterial/veterinary , DNA, Ribosomal/classification , DNA, Ribosomal/genetics , DNA, Ribosomal/isolation & purification , DNA, Ribosomal/microbiology , DNA, Ribosomal/physiology , DNA, Ribosomal/veterinary , Fish Diseases/classification , Fish Diseases/genetics , Fish Diseases/isolation & purification , Fish Diseases/microbiology , Fish Diseases/physiology , Fish Diseases/veterinary , Fishes/classification , Fishes/genetics , Fishes/isolation & purification , Fishes/microbiology , Fishes/physiology , Fishes/veterinary , Flavobacteriaceae Infections/classification , Flavobacteriaceae Infections/genetics , Flavobacteriaceae Infections/isolation & purification , Flavobacteriaceae Infections/microbiology , Flavobacteriaceae Infections/physiology , Flavobacteriaceae Infections/veterinary , Flavobacterium/classification , Flavobacterium/genetics , Flavobacterium/isolation & purification , Flavobacterium/microbiology , Flavobacterium/physiology , Flavobacterium/veterinary , Fresh Water/classification , Fresh Water/genetics , Fresh Water/isolation & purification , Fresh Water/microbiology , Fresh Water/physiology , Fresh Water/veterinary , India/classification , India/genetics , India/isolation & purification , India/microbiology , India/physiology , India/veterinary , Molecular Sequence Data/classification , Molecular Sequence Data/genetics , Molecular Sequence Data/isolation & purification , Molecular Sequence Data/microbiology , Molecular Sequence Data/physiology , Molecular Sequence Data/veterinary , Phylogeny/classification , Phylogeny/genetics , Phylogeny/isolation & purification , Phylogeny/microbiology , Phylogeny/physiology , Phylogeny/veterinary , /classification , /genetics , /isolation & purification , /microbiology , /physiology , /veterinaryABSTRACT
In order to evaluate the genetic variability of the causative agent of cold water disease (CWD), plasmid profiling was used to characterize Flavobacterium (F.) psychrophilum isolates (n = 169). Size analysis of plasmids in F. psychrophilum isolates (n = 128) from several fish species demonstrated that six kinds of plasmids were harbored, and ayu isolates had different profiles compared to other isolates. Moreover, multiple isolates (n = 41) from CWD outbreaks in 2002 to 2003 at a single ayu farm were examined to determine differences between isolates from successive outbreaks and showed different profiles by the sources of seedlings.