Production of multienzymes, bioethanol, and acetic acid by novel Bacillus sp. PM06 from various lignocellulosic biomass

This study focuses on the conversion of lignocellulosic biomass into value-added compounds. Bacillus sp. PM06 can saccharify and ferment all three types of lignocellulosic biomass (wheat bran, sago waste, and rice bran) in submerged fermentation without pretreatment. The isolate Bacillus sp. PM06 can produce both alpha-amylase and cellulase enzymes on all three agrowastes at pH levels ranging from 6 to 8 and temperature ranges of 37-50 degrees C. The optimum conditions for maximum biomass, enzyme production, and carbohydrate utilization on all agrowastes investigated were pH 7, 40 degrees C, and 60 h of fermentation time. Among the lignocellulosic wastes tested, wheat bran was the most potent substrate, induced maximum production of alpha-amylase, cellulase, and biomass to 48.6 +/- 0.51 U/ml, 14.6 +/- 0.5 U/ml, and 18.3 +/- 0.5 g/l, respectively. This hydrolytic activity enhanced carbohydrate utilization to more than 80% for wheat bran, followed by sago waste and rice bran. The fermentative conversion of wheat bran (3% w/v) produced maximum ethanol of 1.83 +/- 0.05 g/l and acetic acid of 7.57 +/- 0.2 g/l, which yielded 27.67% ethanol based on sugar (glucose) fermentation. Scanning electron microscopy (SEM) analysis showed visible structural changes caused by the hydrolytic activity of the enzymes (alpha-amylase and cellulase) produced by the organism. Our study is an effective approach in utilizing low-cost lignocellulosic substrates without pretreatment by a single novel Bacillus sp. PM06. The ability of an organism to produce dual enzymes, bioethanol, and acetic acid makes bioconversions more economically viable.