Isolation and Characterization of β-Galactosidase Producing Bacillus sp. from Dairy Effluent

2 Abstract: β-galactosidase producing BPTK4 was isolated from the diary industry effluent in Chennai . Biochemical tests and 16S rRNA sequencing was used for the confirmation of the strain BPTK4 as Bacillus subtilis. The strain BPTK4 was assessed for its probiotic nature using antibiotic markers. The characterization of the enzyme and optimization of the production medium were carried out for the maximum production and activity of β-galactosidase. Maximum production of enzyme was obtained when the medium was incubated for 48 hours at the temperature of 35°C and maintained at pH 7. Various carbon (1% m/v) and nitrogen (0.015% m/v) sources, metal ions (1mM) and natural substrates (1% m/v) were introduced into the medium and their effects were studied. Xylose, Yeast extract, Mg ion, Mn ion and wheat bran increased the production of enzyme. 2+ 2+ The enzyme was purified by ion exchange chromatography using DEAE sephacel column and it wa s characterized for stability based on temperature and pH. The enzyme showed highest activity at the temperature of 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.