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Isolation of tannase‐producing microbiota from the gastrointestinal tracts of some freshwater fish
Author(s) -
Mandal S.,
Ghosh K.
Publication year - 2013
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/j.1439-0426.2012.02054.x
Subject(s) - biology , tannase , catla , oreochromis , labeo , freshwater fish , carp , food science , microbiology and biotechnology , fishery , biochemistry , gallic acid , fish <actinopterygii> , antioxidant
Summary Tannins are the most abundant among the plant‐derived antinutrients that bind readily with protein and other macromolecules to form indigestible complexes, thereby reducing the nutritional value of the plant feedstuffs. Presence of tannase‐producing gut microbiota in herbivorous animals has been suggested to overcome the antinutritional effects of tannins. However, this topic has been less investigated in herbivorous/omnivorous fish species. The present study was undertaken to evaluate the presence of tannase‐producing autochthonous microbiota in the gastrointestinal ( GI ) tracts of some culturable freshwater teleosts and to identify most promising tannase‐producing strains by molecular methods. Isolation and enumeration of tannase‐producing autochthonous microbiota have been carried out in the gut of ten culturable freshwater teleosts, namely catla ( C atla catla ), silver carp ( H ypophthalmichthys molitrix ), rohu ( L abeo rohita ), grass carp ( C tenopharyngodon idella ), mrigal ( C irrhinus mrigala ), common carp ( C yprinus carpio ), bata ( L abeo bata ), kalbasu ( L abeo calbasu ), tilapia ( O reochromis mossambicus ), and N ile tilapia ( O reochromis niloticus ). Culturable heterotrophic and tannase‐producing microbial populations evaluated on tryptone soya agar and selective tannic acid agar media, respectively, revealed the maximum in the hindguts of all fish species studied. Out of 72 tannase‐producing colonies, 18 randomly selected isolates were maintained as pure cultures and evaluated quantitatively for tannase production. Among these, four most promising tannase producers were identified by 16S/26S r DNA sequencing following nucleotide blast and deposited in the N ational C entre for B iotechnology I nformation ( NCBI ) G en B ank. The strain LR 01 isolated from rohu was a bacterium, E nterobacter asburae ( G en B ank Accession No. GU939631 ). However, the strains CM 02, OM 01 and LR 03 isolated from mrigal, tilapia and rohu were yeasts and identified as P ichia kudriavzevii ( G en B ank Accession No. GU939629 ), C andida tropicalis ( G en B ank Accession No. GU911469 ) and C andida parapsilosis ( G en B ank Accession No. GU939630 ), respectively. To the authors' knowledge, the present study is the first to report tannase‐producing autochthonous microbiota in the gut of freshwater teleosts. Tannin‐degrading microbiota detected in the present study may endow the fish with some ecological advantages by enabling them to overcome the anti‐nutritional effects of plant tannins.