Биохимическая характеристика термостабильной a-амилазы природного изолята Bacillus SP. 1-15

Abstract

Biochemical properties of the recombinant amylase of Bacillus sp. 1-15 isolate were characterized. Expression of the enzyme in Escherichia coli cells was performed by expression plasmid consisting of the amylase gene. The intracellular extract of E. coli cells was used as source of the enzyme. The enzyme had an optimal temperature at 80 to 90 ºC and an optimal pH of 7 to 9. In the absence of Са2+ ions, the amylase of Bacillus sp. 1-15 inactivated by 25 % after 30 min of incubation at 56 ºC. In the presence of 0,2 mM Са2+ ions, the enzyme was active during a long-term incubation at 77 ºC, but rapidly inactivated at temperatures above 84 ºC. The stability of the amylase increased in the presence of Са2+ ions and soluble starch. The amylase activity was significantly prevented by the presence of Co2+, Ni2+, Zn2+, Fe2+, Cu2+ и Cd2+ cations, as well as by EDTA. The enzyme showed an ability to effectively adsorb on granules of raw starch of corn, rice, potato and wheat in rates of 34÷86 %, respectively. In a period of 48 h, the amylase was able to degrade 27÷60 % of glycoside bonds in these starches. The present research showed that amylase from Bacillus sp. 1-15 is characterized by high thermostability, the preference of neutral and slightly alkaline pH values, the stabilization in the presence of Са2+ ions, capability to adsorb and degrade raw starch granules.