The rising alarm of the global population and depletion of fossil fuel results in exploration of alternative fuels. Cellulosic ethanol has attracted attention as an alternative fuel for gasoline since it is clean and sustainable. The bio-ethanol production from cellulosic biomass involves three main steps. It includes pre-treatment, enzymatic hydrolysis and fermentation. The enzymatic saccharification of cellulosic biomass is a crucial step for cost-effective ethanol production. Cellulolytic and hemicellulolytic enzymes are required for the conversion of biomass to simple sugars which further convert into bioethanol. However, a major drawback is the high cost and low titer of cellulase production. So, the motive of our research is to enhance the enzyme production and reduce the enzyme loading in the enzymatic hydrolysis process. Our study demonstrates the isolation and identification of novel cellulolytic fungi and optimizing its culture conditions using Design Of Experiment (DOE) software. After optimization, enzyme production was improved 2.2 folds than unoptimized media. Further, in utilization of crude cellulase from isolated strain in biomass hydrolysis and fermentation showed higher saccharification efficiency and metabolic yield of ethanol compared to the commercial enzyme [1].

However, a mixture of cellulases secreted by one fungal strain shows incomplete degradation of biomass to simple sugars due to the suboptimal levels of the enzyme activities. Arabinose plays a crucial role in improving the yield of ethanol production from agricultural residues. Since the isolated fungal strain did not synthesize arabinofuranosidase, the arabinan degrading thermophilic bacterium was used to produce the arabinosidase enzyme for cellulase cocktail preparation. The arabinan degrading gene from thermophilic bacterium were cloned, over expressed, purified and characterized. Further, fungal cellulase and purified bacterial hemicellulase were used to optimize the enzyme cocktail ratio required for biomass saccharification using the mixture design method. By utilizing the simple lattice design approach, the enzyme loading was reduced up to 37.5 % with improved hydrolysis efficiency. This result indicated the effectiveness of the optimized enzyme formulation at a higher cellulase range that can produce a practical yield of sugar for bio-industry.



Publications:

[1]. Ramiya, B., & Chandraraj, K. (2020). Enhanced production of cellulase from a novel strain Trichoderma gamsii M501 throughresponse surface methodology and its application in biomass saccharification, Process Biochemistry, 99, 48–60.

Book chapter:

[1]. Baskaran, R., Natarajan, V., Joy, S., and Krishnan, C., (2021). Biochemical processing of lignocellulosic biomass for ethanol production. In R.N. Krishnaraj and R.K. Sani (Eds.) Biomolecular engineering solutions for renewable specialty chemicals microorganisms, products, and processes. John Wiley and Sons.