Bio Ethanol Production from Rice Straw Saccharification via <i>Avicelase</i> Gene in <i>E. coli</i> Recombinant Strain

Abstract

The most abundant organic carbon source on Earth is cellulosic materials. Its main resources are crop straws which are not commonly used and produce environmental pollution. These resources can be a site of biological hydrolysis to primary sugars by cellulase enzymes, in which avicelase is the most efficient enzyme in the cellulase family. This work aimed to clone the avicelase gene, transfer it to E. coli, optimize its expression, saccharify rice straw to its primary sugars, and ferment it to bioethanol. The avicelase gene was cloned from the Bacillus subtilis strain and cloned into two E. coli (i.e., DH5α and Bl21) strains. The optimized avicelase activity was described by testing the effect of different media and growth conditions including different carbon and nitrogen sources, as well as pHs and shaking or static conditions. Avicelase enzyme was extracted and used to saccharify rice straw. The obtained glucose was subjected to fermentation by Saccharomyces cerevisiae F.307 under an aerobic condition growth for the production of bioethanol. The ethanol yield was 5.26% (v/v), and the fermentation efficiency was 86%. This study showed the ability to clone one of the cellulolytic genes (i.e., avicelase) for the valorization of rice straw for producing renewable energy and bioethanol from cellulolytic wastes such as rice straw.

Keywords

• rice straw
• <i>avicelase</i> gene
• cloning
• expression optimization
• bioethanol