Abstract

This paper describes the production of α-amylase by Bacillus subtilis NCTC-10400 andBacillus cereus ATCC 14579 using wheat bran as a substrate under Solid State Fermentation (SSF). Supplementation of carbon and nitrogen sources resulted in marginal increase in α-amylase production. Highest production was observed with fructose and ammonium chloride (180.8 U/g) for B. subtilis and with glucose and yeast extract (152.80 U /g) for B. cereus. Addition of Tween 80 to the medium is effective in enzyme production by B. subtilis (230.00 U/g) and B. cereus (180.92 U/g) in SSF. The various environmental process parameters were optimized, namely, moisture level, inoculum concentration, pH, incubation temperature and fermentation period showed 1:2, 10%, pH 7, 35°C and 72 h, respectively for both strains. The obtained crude amylases have optimum substrate concentration at 7% (w/w), optimum pH of 7.0, optimum temperature of 50°C and optimum enzymatic reaction time of 30 min. The potential of the amylase for degrading the starches of wheat bran wastes into glucose was carried out, and then the process was continued by fermentation to produce bioethanol with the result of 2.2 and 1.6% (v/v) by B. subtilis and B. cereus, respectively. In industrial settings, both the inactivation and removal of biofilms are of huge concern. Alpha amylase compounds from both strains were evaluated for their ability to inhibit biofilm formation of several pathogenic bacteria.

Key words: Solid state fermentation (SSF), Bacillus subtilis, Bacillus cereus, wheat bran, α-amylase, bioethanol fermentation, biofilm control.