β-Galactosidase optimization using response surface methodology.

Objective: β-galactosidase (β-D-galactoside galactohydrolase; E. C. 3.2.1.23), or lactase, catalyzes the breakdown of lactose into glucose and galactose. They are naturally available and are produced by many microorganisms such as bacteria, fungi, and yeast. The present study is to explore the possibility of production of this enzyme by Lactobacilli fermentum. Materials and Methods: A loop of inoculum was used for inoculating the culture medium and was incubated at pH 4 and temperature 30°C at 125 rpm. The enzyme activity was checked for at 540 nm in DNS assay, and then, the optimized enzyme was partially purified by ammonium sulfate precipitation. The concentrated enzyme was dialyzed and purified and the molecular weight of the enzyme was measured using high-performance liquid chromatography (HPLC). Response surface methodology showed good significance in the optimization of culture medium parameters. Results: In the present study, it was found that the extracellular β-galactosidase production by the L. fermentum in a submerged skim milk broth was maximum 7.99 U/mL/min enzyme units under optimized the culture medium of its carbon and nitrogen source. Conclusion: This method could be exploited for commercial production of beta-galactosidase enzyme. [ABSTRACT FROM AUTHOR]