Study On Enzymatic Hydrolysis Of Sugarcane Bagasse By Xylanase From Streptomyces Ipomoeae And Cellulase

Sugarcane bagasse is one of the most abundant lignocellulose raw materials in the world.Fermentation of reducing sugars obtained from the hydrolysis of lignocellulose to produce biofuels can not only alleviate the fossil energy crisis,but also solve the environmental problems caused by the accumulation of lignocellulosic waste.In order to solve the bottleneck problem of low cellulase hydrolysis efficiency and high cost,the strategy of multi-enzyme synergistic degradation is often adopted.Xylanase has the property of hydrolyzing hemicellulose and can cooperate with cellulase to promote the biotransformation of lignocellulose.In this paper,the novel xylanase Sipo En Xyn10A(Xyn10A)from Streptomyces ipomoeae was used as the research object to systematically investigate the behavioral characteristics of its synergy with cellulase to digest bagasse.First of all,the effect of bagasse pretreatment methods on synergistic enzymatic hydrolysis was studied.Among the selected pretreatment methods,alkaline hydrogen peroxide AHP? has the best treatment effect.When Xyn10 A and cellulase were reacted for 24 h under the co-addition,the yield of reducing sugar reached 3.01 g/L,the degree of synergy(DS)reached 1.65,the sugar yield was 12 times higher than that of the mechanical grinding pretreatment,it was believed that lignin content was one of the factors affecting the yield of reducing sugar.The optimal coordination conditions of Xyn10 A synergistic cellulase were p H 5.5 and temperature 50 ?.Compared with the single cellulase group,the synergistic enzyme group could maintain the sugar yield of 3.3 g/L in the reaction system in a wider range from p H 4.5 to p H 6.0,and the relative synergistic effect was about 30% to 50%.Response surface methodology was used to explore the effects of various factors on reducing sugar yield and synergy,it was found that the change of the enzyme loading of cellulase C2730 had the most significant effect on the reducing sugar yield,while Xyn10 A had the most significant effect on the DS,and the interaction between Xyn10 A and ?-glucosidase alone could not significantly change the reducing sugar yield.The total enzyme loading was further promoted to 24 mg/g substrate,and the DS for reducing sugars reached the highest level(1.88).At the total enzyme loading of 72 mg/g substrate,the reducing sugar yield of the synergistic enzyme group at 24 h was 17.41 g/L,which was 45% higher than that of the single cellulase(11.98 g/L).Thecorresponding glucose yield was 84.83%,and the DS was 1.36.The yield of xylose was 81.67%,and the DS was 1.17.Taking the monosaccharide yield as an indicator,the influence of Xyn10 A ratio on synergism was studied,it was found that replacing cellulase with an equal ratio of 12.5% Xyn10 A can increase glucose yield by 78% and xylose yield by 50%,and the highest DS for glucose and xylose could reach 2.57 and1.84 respectively.At the same time,the rate of synergistic hydrolysis increased evidently.Under the same glucose yield,the reaction time of the synergistic enzyme group was shortened by 72 h compared with that of the monocellulase group,and the reaction time for the xylose yield was shortened by 96 hours.It showed that even a small amount of loading of Xyn10 A could make the enzymatic hydrolysis reaction produce more hydrolyzed sugars in a shorter time,which provided the possibility for the industrial application of Xyn10 A.According to the preliminary experiments,the pre-adsorption of Xyn10 A on the lignocellulose substrate did not affect the monosaccharide yield of the hydrolysis process,suggesting that the synergistic effect was more likely to come from substrate-degradation by Xyn10 A rather than Xyn10A-adsorption on substrate.