Xylanase production by a thermo-tolerant Bacillus species under solid-state and submerged fermentation

Abstract

Effects of xylose on xylanase production by a thermophilic Bacillus sp showed diverse patterns on corn cob (CC) and wheat bran (WB) as sole carbon sources in solid-state fermentation (SSF) and submerged fermentation (SmF). Supplementation of these media with either mineral salt solution (MSS) or yeast extract peptone (YEP) also exerted variable effects. While under SSF, xylose stimulated xylanase synthesis by 44.01%, on wheat bran supplemented with MSS, it decreased the enzyme activity by 12.89% with YEP supplementation. In SmF, however the enzyme synthesis was stimulated by xylose on supplementation with both MSS and YEP by 41.38% and 27.47%, respectively. On corn cob under SSF, xylose repression was significant both with MSS (26.92%) and YEP (23.90%) supplementation. Repression by xylose also took place on corn cob and YEP (19.69%) under SmF, while significant stimulation (28.55%) was observed by MSS supplementation. The possible role of media composition and fermentation conditions in the regulation of xylanase synthesis by xylose is discussed.