Xylanase Production by Bacillus subtilis Using Carbon Source of Inexpensive Agricultural Wastes in Two Different Approaches of Submerged Fermentation (SmF) and Solid State Fermentation (SsF)

Abstract

Xylanase has become an attractive enzyme due to its enormous economical roles especially as bio-bleaching agent in pulp and paper industry. Thus, in order to reduce the cost of production, the cheapest alternative carbon source is desirable under submerged (SmF) and solid state fermentation (SsF). Therefore, the objective of the study is to involve the use of two approaches of SmF and SsF to identify their potential ability on the production of xylanase by Bacillus subtilis ATCC 6633 using sustainable cost effective agricultural wastes to replace the expensive xylan as the prime carbon source. Seven defined, undefined and minimal Medium A to G in SmF were investigated to determine the optimum medium formulation. Thereafter, the carbon source was replaced with various agricultural wastes in SmF and SsF, respectively. On the other hand, the replacement of xylan with agricultural wastes as the alternative carbon source in SmF and SsF is particularly essential in industrial production. Based on our results, xylanase activity of 11.099 ± 1.127 U/mL was detected from the undefined Medium F. Nonetheless, higher xylanase activity of 11.646 ± 4.163 U/mL was obtained after the carbon source was replaced with barley husk in SmF. Notably, when wheat bran was substituted in SsF, 2.50×109 cells/mL of biomass concentration and 22.071 ± 0.186 U/mL of xylanase activity were obtained at 48 h of fermentation. These findings successfully displayed significant potential of scaling up for industrial xylanase production using inexpensive agricultural wastes in both approaches of SmF and SsF. In the nutshell, the production of xylanase using agricultural wastes of barley husks and wheat bran as the alternative carbon and energy source in SmF and SsF was more economically advantages and environmentally conscious than the use of expensive xylan substrate in term of lowering the costs of capital and operation in the industrial point of view.