Amylase hyperproduction by deregulated mutants of the thermophilic fungus Thermomyces lanuginosus

Abstract

Thermomyces lanuginosus was subjected to three cycles of mutagenesis (UV/NTG) and a selection procedure to develop amylase-hyperproducing, catabolite-repression-resistant and partially constitutive strains. One of the selected derepressed mutant strain III(51), produced approximately 7- and 3-fold higher specific activity of alpha-amylase (190 U/mg protein) and glucoamylase (105 U/mg protein), respectively, compared to a wild-type parental strain. Further, the effect of production parameters on mutant strain III(51) was studied using a Box-Behnken design. The regression models computed showed significantly high R(2) values of 96 and 97% for alpha-amylase and glucoamylase activities, respectively, indicating that they are appropriate for predicting relationships between corn flour, soybean meal and pH with alpha-amylase and glucoamylase production.