Prospects of reusable endogenous hydrolyzing enzymes in bioethanol production by simultaneous saccharification and fermentation

Abstract

This study was conducted to evaluate the presence, origination and classification of various hydrolyzing enzymes from malt and their specified hydrolyzing effects on various substrates for bioethanol production and to link these characteristics with the future prospects of bioethanol production. These enzymes are categorized as cell wall, starch, protein, lipid, polyphenol and thiol hydrolyzing enzymes based on their substrate specificity. Waste from beer fermentation broth (WBFB) has been evaluated as a rich source of malt derived hydrolyzing enzymes with significant self potential for bioethanol production. However, yeast cells cannot survive at the high temperature required for the saccharification activities of hydrolyzing enzymes during simultaneous saccharification and fermentation (SSF). This dilemma might be resolved by bioethanol production at elevated temperatures via cell-free fermentation systems in the presence of malt hydrolyzing enzymes. Moreover, emerging technologies such as genetic engineering in biomass and biotransformation in cell-free enzymatic systems will likely hasten bioethanol production in the near future. The present study adds new dimensions to eco-friendly bioethanol production from renewable and waste energy resources based on the specific hydrolyzing activities of malt enzymes.