Synergistically Enhanced Enzymatic Hydrolysis of Sugarcane Bagasse Mediated by a Recombinant Endo-Xylanase from Streptomyces ipomoeae

Xylanase is commonly thought to effectively cooperate with cellulase to promote the bioconversion of lignocellulose. In this study, a novel xylanase, SipoEnXyn10A (Xyn10A), previously identified from Streptomyces ipomoeae, was employed to investigate its synergetic effects on sugarcane bagasse (SCB) transformation. It was shown that the relative increase in reducing sugars reached up to 65%, with enhanced yields of glucose and xylose by 78% and 50%, respectively, in the case of the replacement of cellulase with an equivalent amount of Xyn10A at an enzyme loading of 12.5%. The highest degrees of synergy (DS) for glucose and xylose could reach 2.57 and 1.84. Moreover, the hydrolysis rate increased evidently, and the reaction time to reach the same yield of glucose and xylose was shortened by 72 h and 96 h, respectively. This study on synergistic mechanisms demonstrated that the addition of Xyn10A could cause the destruction of substrates’ morphology and the dissolution of lignin components but could not change the accessibility and crystallinity of substrate cellulose. The joint effect of cellulase and xylanase during the hydrolysis process was thought to result in a synergistic mechanism.