A highly inducible β-galactosidase from Enterobacter sp.

Enterobacter sp. 3TP2A isolated from petroleum station was found to produce a novel, highly inducible mesophilic intracellular β-galactosidase in the presence of lactose upto 76.5 U mg -1 . The enzyme was purified to 17.3-fold after gel permeation chromatography with a yield of approximately 11 %. The optimium pH and temperature values of purified enzyme were found to be 8.0 9.0 and 35 o C, respectively. The Molecular weight of the enzyme was approx. 60 kDa of a single band by both SDS-PAGE and native-PAGE, as well as estimated by gel filtration chromatography. The enzyme was inhibited by Zn 2+ and EDTA, while Cu 2+ had strong inhibitory effect even at low concentrations. Activation by Mg 2+ and inhibition by EDTA show that the enzyme is metal-dependent or a metalloenzyme. The enzyme was slightly activated by β-mer­captoethanol, while slightly inhibited by Iodoacetamide. On the other hand, PCMB inhibited the enzymatic activity to a great extent, whereas it was completely inhibited by N-ethylmaleimide. The V max and K m values were calculated as 0.701 μmol min -1 and 0.104 mM, respectively. The results indicated that the β-galactosidase Enterobacter sp. 3TP2A may well be a good candidate for use in biotechnology, particularly in the area of environment and health.