MUTANT MICROBIAL .ALPHA.-AMYLASES WITH INCREASED THERMAL, ACID, AND/OR ALKALINE STABILITY

摘要

Thermostable and acid stable .alpha.-amylases are provided as expression products of genetically engineered .alpha.-amylase genes isolated from microorganisms, preferably belonging to the class of Bacilli. Both chemical and enzymatic mutagenesis methods are e.g. the bisulphate method and enzymatic misincorporation on gapped heteroduplex DNA. The mutant .alpha.- amylases have superior properties, e.g. improved thermostability over a broad pH range, for industrial application in starch processing and textile desizing.