Enzyme production by solid-state fermentation on soybean meal: A comparative study of conventional and ultrasound-assisted extraction methods

Abstract

Protease, cellulase, and alpha-amylase producing Bacillus subtilis strain was cultivated by solid-state fermentation technique using soybean meal as a substrate. The aim of the present study was to establish a highly efficient enzymes' extraction method as a first stage in downstream processing. The conventional extraction procedure was optimized by determining pH, stirring rate, solid/liquid ratio, and time of extraction on enzymes' recoveries from fermented soybean meal. Yields of leached enzymes were compared to the amounts of enzymes that are achieved with ultrasound-assisted extraction (UAE). UAE was established to be superior method for obtaining higher yields of proteases (up to 330 IU) and alpha-amylases (825 IU), under significantly shorter extraction time and gaining more concentrated product. However, the obtained model predicts that conventional process led to a product with a higher cellulolytic activity ( gt = 7.5 IU).