An Optimised Combination Approach of Physicochemical Methods for Separate Hydrolysis and Fermentation (SHF) Pretreatment of Wheat Straw for High Production of Bio-alcohol

Abstract

Production of bio-ethanol from lignocellulosic waste like wheat straw has been a very attractive approach since earlier. However, production of ethanol is compromised from lignocellulosic waste due to its tough and crystalline structures. To resolve this issue, the combination of physical methods (such as milling, irradiation, steam) and chemical methods (such as NaOH treatment) has been explored in our study for the pre- treatment of wheat straw during separate hydrolysis and fermentation (SHF) steps. Fungus VBVI (Aspergillus terreus) and Saccharomyces cerevisiae were used for the Microbial hydrolysis and Fermentation respectively for the optimization of alcohol production. Interestingly, we observed that content of xylan and lignin from wheat straw gradually decreases during pre-treatment events, which facilitates the overall enhanced alcohol production. Amount 10gL-1 of pre- treated wheat in nutrient media treated with Aspergillus terreus VB (VI) inoculum and was observed high cellulase and xylanase activity rapidly post 120 hrs of inoculation. Later on, Saccharomyces cerevisiae was inoculated for fermentation once the saturated microbial hydrolysis was achieved. After 192 hrs, 3gL-1ethanol was observed to be produced, indicating conversion rate and ethanol yield 45.6% and 18%respectively of the theoretical maximum values reported so far. Our study suggested that strain VBVI (Aspergillus terreus) has a very good potential for enhanced bio-ethanol production from wheat straw. Moreover, different steps of pre-treated method have also been optimized and explored in this study for the overall production of ethanol. Overall, this study reveals out an easier and cheaper approach to scale up the industrial bio-alcohol production.