Production and characterization of β-galactosidase from the fungus Thielaviopsis ethacetica Went.

Abstract

β-galactosidase (EC 3.2.1.23) is an industrially important enzyme. It can catalyse two different types of reactions, namely lactose hydrolysis and transgalactosylation. β-galactosidase enzyme production by Thielaviopsis ethacetica, was investigated and the enzyme was partially purified and characterized in the present study. Qualitative assay for the pre β-galactosidase activity indicated the formation of water insoluble blue-green colour, dichloro-dibromo-indigo zone towards the edges of the fungal colony after a 72-hour incubation period. Quantitative assay recorded a maximum enzyme activity of 0.599 U/mL at 72 hours. The enzyme was partially purified from the crude enzyme using ammonium sulphate precipitation and dialysis. Fraction 40-60 % (fraction 2) had the highest specific enzymes activity of 1.65 U/mg with 8.68 purification fold and 28.3 % recovery. SDS-PAGE analysis of fraction 2 resulted three separate protein bands above 40 kDa. The protein band corresponding to 50 kDa molecular weight was confirmed as β-galactosidase. The optimum temperature and pH for the enzyme was at 60 ̊ C and 7.0, respectively. The present study reveals the fungal strain Thielaviopsis ethacetica with β-galactosidase activity. To our knowledge this is the first report about β-galactosidase activity of the strain T. ethacetica. This investigation suggests the potential use of this species in industrial applications.