Evaluation of Pretreatment Methods (Acid and Alkali) in Improving the Enzymatic Saccharification of Sugarcane Baggase: Structural and Chemical Analysis

Abstract

Background: Enhancement of cellulase and xylanase production and improvement of more proficient lignocellulose-degrading enzymes are essential in order to decrease the price of enzymes required in the biomass-to-bioethanol production. Results: The effectiveness of different concentration of alkali and acid pretreatment of sugarcane bagasse for improving the enzymatic saccharification of cellulose has been evaluated. The sugarcane bagasse was characterized to contain 39.52% cellulose, 25.63% hemicelluloses, 30.36% lignin, 1.44% ash and 2.90% other extractives. Afterthat, The sugarcane bagasse was pretreated with two different concentrations (5% and 10%) of H2SO4 and NaOH at 121°C for 60 min. Among them, the best result was obtained when sugarcane bagasse was pretreated with 10% NaOH solution followed by 10% H2SO4, 5% NaOH and 5% H2SO4 solution. The highest cellulose saccharification was 489.5 mg/g from 10% NaOH pretreatment followed by 322.75mg/g, 301.25 mg/g and 276.6 mg/g from 10% H2SO4, 5% NaOH and 5% H2SO4, respectively, which were 55.1, 32.0, 27.1 and 20.6 times higher than the control. Moreover, the FTIR, XRD and SEM analysis showed significant molecule and surface structure changes of the sugarcane bagasse after different pretreatments. Cellulase and xylanase produced by Pseudomonas sp. CVB-10 [MK443365] and Bacillus paramycoides T4 [MN370035] was used to hydrolyze the pretreated sugarcane bagasse and the optimal condition was determined to be 30 h of enzymatic reaction with 3:1 ration of enzymes under the temperature of 55°C, pH 5.5, substrate concentration of 3% and Tween-20 0.5%. Conclusion: Enzyme supernatants produced by the mixed culture of Pseudomonas sp. CVB-10 [MK443365] and Bacillus paramycoides T4 [MN370035] on various pretreated sugarcane baggase have good cellulase and xylanase activities, leading to celluloses and Hemicelluloses conversion in the enzymatic hydrolysis/saccharification that is more proficient.