Abstract

The optimization of medium composition for α-galactosidase production by an Antarctic bacterial isolate, Bacillus sp. LX-1 was investigated in flask fermentation. The Central composite design (CCD) with 3 variables (galactose, peptone and MnSO₄) was employed to derive statistical model (Response surface methodology: RSM) for optimizing the medium composition. The results show the optimum medium composition of 16.5 g/L galactose, 6.2 g/L peptone and 0.0018 g/L MnSO₄ with predicted α-galactosidase activity, 1.17 U/mL and observed activity from the fermentation with optimized medium was 1.06 U/mL. The optimized value was 6.3-fold higher than that (0.168 U/mL) previously obtained under basal conditions. Thus, medium optimization using RSM is suggested to play a significant role in enhancing the production of α-galactosidase by Bacillus sp. LX-1.

Key words: α-Galactosidase, Bacillus sp. LX-1, medium optimization, central composite design (CCD), response surface methodology (RSM).