Production and partial characterization of -galactosidase activity from an Antarctic bacterial isolate, Bacillus sp. LX-1

Abstract

An Antarctic Bacillus sp. isolate was found to exhibit extracellular α-galactosidase activity. On the basis of the results of 16S rRNA sequencing, the strain was named Bacillus sp. LX-1. In a one-factor-at-a-time experiment, galactose, peptone and Mn²⁺ were found to be the medium components that facilitated enzyme production. The new strain showed optimal α-galactosidase activity at pH 7.0 and temperature of 40°C. The enzyme exclusively hydrolyzed α-D-galactosides such as p-nitrophenyl--galactopyranoside, melibiose, raffinose and stachyose, and showed no effect with proteases such as trypsin, pancreatin, and pronase. Enzyme activity was almost completely inhibited by the presence of Ag⁺, Hg²⁺, Cu²⁺, and sodium dodecylsulfate (SDS) but was unaffected by β-mercaptoethanol and ethylenediaminetetraacetic acid (EDTA). The LX-1 α-galactosidase may be a promising candidate as a biocatalyst for soybean processing in food and feed industries.

Key words: Antarctic, Bacillus sp., α-galactosidase, one-factor-at-a-time, biocatalyst.