Bacillus subtilis α-amylase,lichenase, β-mannanase and xylanase: Screening for their induction by agro-industrial byproducts and precipitation by organic solvents

Current research focuses on the utilization of low value agro-industrial byproducts for targeting B. subtilis towards different exoenyzeme lines. This includes α-amylase, β-mannanase, xylanase, and lichenase. As an orientation step, growth and α-amylase activity were monitored in three different nutritional media. A medium which showed low levels of catabolite repression and spore development was selected as a basal fermentation medium. Different patterns of exoenzyme induction were obtained when beet pulp, corn cob, rice husk, wheat bran, and wheat straw were separately used to partially replace the nutrient contents of the selected medium. α-Amylase and lichenase were maximally expressed in the presence of corn cob or beet pulp. On the other hand, considerable levels of the four polysaccharide hydrolyzing enzymes were induced by wheat bran. β-mannanase and xylanase expression responded more significantly towards inducers than α-amylase and lichenase. The effects of five different organic solvents as precipitative agents on these exoenzymes were also studied.