Abstract

PURIFICATION OF BETA GALACTOSIDASE ENZYME FROM DAIRY EFFLUENT BACILLUS SPECIES

V. Pavithra and *Dr. J. Thirumagal

Abstract

Beta-galactosidases are the highly demanded enzymes in the diary industries for the hydrolysis of lactose into its constituent monosaccharides. Thermostable beta-galactosidases producing Bacillus sp D4 can be used as a probiotic food for lactose intolerant people. In the present study, the Bacillus sp was isolated from the diary industry effluent in Chennai and screened with X-Gal media. The Bacillus sp. strain D4 was characterized by biochemical test and identified based on 16S rDNA sequencing and their phylogenetic analysis was carried out. The strain D4 was assessed for its probiotic nature using antibiotic markers. The characterization of the enzyme and optimization of the production medium were very important in determining the maximum production and activity of beta-galactosidase. Maximum production of enzyme was obtained when the medium was incubated for 48 hours at 37°C and maintained at pH 7. The addition of various carbon, nitrogen, aminoacid sources, metal ions and natural substrates to the medium were studied at concentration 1% m/v. Xylose, Yeast extract, L-phenylalanine, Mg2+ ion, Mn2+ ion and wheat bran increased the production of beta galactosidase. The enzyme was partially purified by acetone and ammonium sulphate precipitation and characterized based on the temperature, pH. The enzyme showed highest activity at 55°C (0.350 U/ml) and at pH 7 (0.294 U/ml). The enzyme retained 100% of its activity at 45°C and retained 90% of its activity at pH 7.

Keywords: Bacillus sp, probiotic, X-Gal, ONPG, beta-galactosidase.