New host record of five Flavobacterium species associated with tropical fresh water farmed fishes from North India

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.

Isolation and Characterization of Flavobacteriaceae from Farmed and Wild Nile Tilapia in Tanzania

“…). Flavobacterium indicum was isolated from skin and gill samples of different fish in India (Verma and Rathore ), and F. aquatile was reported in diseased fish in Michigan (Loch et al. ).…”

“…Other species that have been isolated from diseased fish and are described as opportunistic pathogens include F. aquatile , F. hydatis , F. succinicans , F. indicum , and C. joostei , among others (Bernardet et al. ; Loch and Faisal ; Verma and Rathore ; Dong et al. ).…”

“…The medium has been found to have widespread use for the isolation of Flavobacteriaceae from diseased fish (Austin and Austin ). As many Flavobacteriaceae grow relatively poorly in vitro and phenotypic identification involves lengthy biochemical procedures, amplification and sequencing of the 16S ribosomal RNA (rRNA) gene is commonly used as a confirmatory analysis to distinguish between species and isolates (Darwish and Ismaiel ; Verma and Rathore ).…”

On the role, ecology, phylogeny, and structure of dual-family immunophilins

“…Essentially, all Flavobacteria switch from rodshaped cells to long filaments that can intertwine to form clumps (Jooste and Hugo 1999). They also contain a variety of pigments such as yellow pigments (Verma and Rathore 2015) or proteorhodopsin and can be stimulated by light (Gómez-Consarnau et al 2007); Yoshizawa et al 2014). In another example, R. biformata forms characteristic rusty red pigmented colonies and, like many Flavobacteria, contains genes for the complex pathway of carotenoid biosynthesis (Oh et al, 2009).…”

Pathology of Flavobacterium sp. KG3 in Experimentally Challenged Ornamental Goldfish Carassius auratus (L.)

“…in Carassius auratus in C. auratus (4) were documented in India. They were also isolated in healthy carps (16). The reports on the pathogenic potential of these bacteria on cultured fish and their systematic pathology are scanty.…”