Lactose hydrolysis by b - galactosidase from a newly isolated bacterial strain Bacillus sp. NV1

β-Galactosidase (EC 3.2.1.23) was produced from mesophilic bacterial strain Bacillus sp. NV1 from local milk plant. The enzyme was partially purified using ammonium sulphate (20-70%). The optimum temperature of β-galactosidase was 400C and pH range was 6-7. The enzyme was quite stable and lost 40% activity in 6 h at 500C with t of 3 h at 550C. The enzyme was slightly inhibited by Fe3+ and Cu2+ and activated by Na+, Ni+, Ca+ and Zn+, Co2+ with K of 20.83 mM and V m max of 204.08 U/ml. The partially purified enzyme hydrolyzed 98% of lactose (5%) within 12 h of incubation thereby making this enzyme useful for various industrial purposes.