科研之友
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摘要
A bacterial strain capable of producing extracellular alpha-galactosidase was isolated from a sample of sugarcane industrial waste. Microbiological, physiological, and biochemical studies revealed that the isolate belonged to Bacillus sp. Furthermore, based on a 16S rDNA sequence analysis, the new isolate was identified as Bacillus megaterium VHM1. The production of alpha-galactosidase was optimized based on various physical culture conditions. Guar gum and yeast extract acted as the best carbon and nitrogen sources, respectively. The optimum pH was 7.5 and the enzyme remained stable over a pH range of 5-9. The enzyme was optimally active at 55 degrees C and thermostable with a half-life of 120 min, yet lost 90% of its residual activity within 120 min at 60 degrees C. One mM concentrations of Ag-2, Cu-2, and Hg2+ strongly inhibited the alpha-galactosidase, whereas the metal ions Fe-2, Mn2+, and Mg2+ had no effect on the alpha-galactosidase activity, and Zn2+, Ni2+, and Ca2+ reduced the enzyme activity slightly. When treated with the B. megaterium VHM1 enzyme, the flatulence-causing sugars in soymilk were completely hydrolyzed within 1.5 h.
- 出版日期2010-11
