To study the influence of different components of fermentable substrates on induction of extracellular α-amylase synthesis by Bacillus subtilis DM-03 in solid-state fermentation and exploration of feasibility for inclusion of α-amylase in laundry detergent formulations

Abstract

Study on potential of different agro-industrial waste residues for supporting α-amylase production by a thermophilic strain of Bacillus subtilis DM-03 in solid-state fermentation (SSF) was initiated and potato peel was found to be the best substrate for α-amylase production. Linear multiple regression analysis showed that higher starch contents of the fermentable substrates enhanced the α-amylase synthesis while the higher sugar content of the substrates imposed a negative effect presumably due to catabolic repression of the enzyme synthesis. Furthermore, C/N ratio of the substrates also played a critical role in induction of α-amylase synthesis. The result of batch fermentation showed 532 ± 5 U of α-amylase production per gram of dry substrate by B. subtilis DM-03 post-72 h of incubation under optimized SSF condition. The crude α-amylase enzyme from B. subtilis DM-03 strain demonstrated excellent stability and compatibility with the laundry detergents that favors its inclusion in commercial laundry detergent formulations.