… to meet more ambitious targets will require alternative feedstocks. Lignocellulosic biomass from agricultural residues, municipal paper waste, dedicated energy crops and multiple other sources is projected to be a major renewable feedstock for sustainable production of biofuels.
According to Joseph Rich, leader of the USDA Bioproducts and Biocatalysis Research Unit in Peoria, Ill., "Industry is awaiting the microorganism that can produce high levels of ethanol in large-scale fermentation containing the hydrolysate consisting of both pentose and hexose sugars released by mechanical, enzymatic and chemical treatment of lignocellulosic feedstocks."
Enzyme Requirements for Lignocellulosic Feedstocks
Although S. cerevisiae is a proven industrial ethanol producer in traditional starch-based processes, it will be no easy task to provide this microorganism with the ability to convert lignocellulosic biomass to ethanol. The carbohydrate components of lignocellulose (cellulose and hemicellulose) are tightly bound to lignin, making the sugars largely inaccessible to enzymes. "Before enzymatic hydrolysis, pretreatment with acid or alkali is generally needed to fully maximize the release of sugars from any lignocellulosic biomass," says Badal
Developing New Biocatalysts
Producing a yeast strain with optimized sets of cellulases and hemicellulases requires screening thousands of combinations of these biomass-degrading enzymes for enzyme activity. Automation is essential in carrying out these operations. A team of scientists at the NCAUR laboratory has been successful in designing a robotic platform and creating the automated molecular biology routines necessary to screen for the most effective set of enzymes.
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