Improving Enzymes for Biomass Conversion: A Basic Research Perspective

Abstract

The cost of enzymes for converting plant biomass materials to fermentable sugars is a major impediment to the development of a practical lignocellulosic ethanol industry. Research on enzyme optimization with the goal of reducing the cost of converting biomass materials such as corn stover into glucose, xylose, and other sugars is being actively pursued in private industry, academia, and government laboratories. Under the auspices of the Department of Energy Great Lakes Bioenergy Research Center, we are taking several approaches to address this problem, including "bioprospecting" for superior key enzymes, protein engineering, and high-level expression in plants. A particular focus is the development of synthetic enzyme mixtures, in order to learn which of the hundreds of known enzymes are important and in what ratios. A core set comprises cellobiohydrolase, endoglucanase, β-glucosidase, endoxylanase, and β-glucosidase. Accessory enzymes include esterases, proteases, nonhydrolytic proteins, and glycosyl hydrolases that cleave the less frequent chemical linkages found in plant cell walls.

Recombinant expression and characterization of an endoglucanase III (cel12a) from Trichoderma harzianum (Hypocreaceae) in the yeast Pichia pastoris

“…The main disadvantage of acid hydrolysis is the generation of fermentation inhibitors (Galbe and Zacchi, 2002). The use of microbial enzymes is an attractive alternative for cellulose depolymerization due to the specificity and efficiency of the enzymes as well as the non-inhibitor feature and rapid hydrolysis (Arantes and Saddler, 2010;Banerjee et al, 2010).…”

Obtaining New Cultures Of Microorganisms That Produces Cellulases And Xylanases From The Sugarcane Bagasse

“…T. harzianum are frequently reported as control agent against fungal pathogens (Arantes and Saddler 2010;Banerjee et al 2010). However, recent studies have also revealed the potential of this fungus for cellulase production and industrial applications (Ahmed et al 2009;Castro et al 2010aCastro et al , 2010b.…”

Optimization of Process Conditions for the Production of Holocellulase by a <i>Bacillus</i> Species Isolated from Nahoon Beach Sediments

“…Presently, commercial production of cellulases and xylanases is mostly from fungi such as Trichoderma and Aspergillus species, which may have attained maximal yield, having undergone extensive strain improvement over the years (Banerjee et al, 2010;Peterson and Nevalainen, 2012). Moreover, these commercial enzymes are still limited by the high cost of production, narrow substrate reaction and instability under industrial process dynamics (Motta et al, 2013).…”

“…Consequently, considerable efforts are being made to increase microbial cellulase and xylanase production by environmental strains (Kim et al, 2007). In that context hemi (cellulolytic) bacterial strains are continuously being sourced from diverse environments with a view to finding better alternative producers or other cellulases and xylanases capable of enhancing existing commercial enzyme cocktail preparations (Banerjee et al, 2010). Therefore investigation on novel bacterial strains adaptable to industrial process dynamics and capable of producing cellulases and xylanases with favourable industrial characteristics is ongoing (Sepahy et al, 2011;de Souza Vandenberghe et al, 2016).…”