Engineering of the α-amylase from geobacillus stearothermophilus US100 for detergent incorporation

AmyUS100ΔIG is a variant of the most thermoactive and thermostable maltohexaose forming α-amylase produced by Geobacillus stearothermophilus sp.US100. This enzyme which was designed to improve the thermostability of the wild-type enzyme has acquired a very high resistance to chelator agents. According to modeling structural studies and with the aim of enhancing its resistance towards chemical oxidation, a mutant (AmyUS100ΔIG/M197A) was created by substituting methionine 197 to alanine. The catalytic proprieties of the resulting mutant show alterations in the specific activity and the profile of starch hydrolysis. Interestingly, AmyUS100ΔIG/M197A displayed the highest resistance to oxidation compared to the AmyUS100ΔIG and to Termamyl300®, the well-known commercial amylase used in detergent. Further, performance of the engineered α-amylase was estimated in the presence of commonly used detergent compounds and a wide range of commercial detergent (liquid and solid). These studies indicated a high compatibility and performance of AmyUS100ΔIG/M197A, suggesting its potential application in detergent industry. © 2008 Wiley Periodicals, Inc.