Phytase producing autochthonous bacteria have been isolated from the proximal intestine (PI) and distal intestine (DI) of three Indian major carps, rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) and one minor carp, bata (Labeo bata). In modified phytase screening medium (MPSM), phytase-producing strains were recorded at higher densities in the PI of rohu and minimum in the PI of bata. Out of 45 isolates, 4 bacterial strains were selected as potent phytase producers according to quantitative enzyme assay. Maximum phytase activity was detected in LRF5 isolated from the PI of L. rohita followed by CCF2 isolated from the PI of C. catla. Among the selected isolates, three (LRF5, LRH2 and CMH1) were Gram positive rods, whereas CCF2 was Gram positive coccus. All the four isolates could tolerate a wide range of temperature (25–42 °C) and pH (6.0-9.0). The isolate LRH2 was most thermostable as it was able to survive up to 55 oC. On the basis of 16SrDNA partial sequence analysis, isolates LRF5 and CCF2 were identified as Bacillus cereus (GenBank Accession no. KC894957.1) and Staphylococcus caprae (Accession no. KC894956.1), respectively. Whereas, the isolates LRH2 and CMH1 were most closely related to Bacillus licheniformis (Accession no. KF011267.1) and Lysinibacillus fusiformis (Accession No. KF011266.1), respectively.
Fish GI tract, bacteria, phytase, 16S rDNA, identification