AUTOCHTHONOUS PHYTASE-PRODUCING BACTERIA ISOLATED FROM THE GASTROINTESTINAL TRACTS OF FOUR INDIAN FRESHWATER TELEOSTS: CHARACTERIZATION AND IDENTIFICATION

Suhas Kumar Dan,Arun Kumar Ray,Goutam Banerjee,Pinki Ghosh,Ankita Nandi

doi:10.15414/jmbfs.2015.4.4.342-346

Suhas Kumar Dan, Arun Kumar Ray + Show 3 more

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https://doi.org/10.15414/jmbfs.2015.4.4.342-346

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Abstract

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.

Highlights

Phytases are the enzymes which catalyze the hydrolysis of phytic acid to myo-inositol and inorganic phosphates
Phytase-producing bacterial count was maximum in the proximal intestine (PI) of L. rohita and in distal intestine (DI) it was maximum in L. bata
The strain LRF5 showed highest phytase activity among all the strains, followed by CCF2, while the strain LRH2, isolated from the DI of L. rohita showed highest activity among the strains isolated from distal intestine, followed by CMH1, isolated from the DI of C. mrigala

Summary

Introduction

Phytases (myo-inositol hexaphosphohydrolases; E.C. 3.1.3.8) are the enzymes which catalyze the hydrolysis of phytic acid to myo-inositol and inorganic phosphates. Phytate is generally regarded as an anti-nutrient in animal feed and for human consumption, as it effectively chelates metal ions such as Ca2+, Mg2+, Zn2+and Fe 2+ and may results in mineral deficiency (Noureddini and Dang, 2008) It forms complexes with lipid, starch and proteins and affects their digestion and may inhibit digestive enzymes like α-amylase, trypsin, acid phosphatase and tyrosinase (Cosgrove, 1966; Harland and Morris, 1995; Caipang et al, 2011; Khan and Ghosh, 2013). The plant proteins sources are generally rich in anti-nutritional factors like phytic acid which restrict their inclusion in animal diet.One way to reduce the phytate content is treating them with microbial phytase which is considered as a better option than chemical digestion (Roy et al, 2009). The application of phytase in aquaculture is limited because of the lack of phytases with appropriate properties, insufficient information about feeding experiment, and manufacturing difficulties (Huang et al, 2009)

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