Engineering Recombinant Organisms for Next-generation Ethanol Production
Eugéne van Rensburg, Riaan den Haan, Daniël C. la Grange, Heinrich Volschenk, Willem H. van Zyl and Johann F. Görgens
from: Biofuels: From Microbes to Molecules (Edited by: Xuefeng Lu). Caister Academic Press, U.K. (2014)
Development of microbes for the production of fuel ethanol continues at a rapid pace, for established first generation processes relying on sugar- and starch-based foodcrops, and second generation processes for conversion of lignocellulose to ethanol by pretreatment-hydrolysis-fermentation. The production of bio-ethanol is dominated by Saccharomyces cerevisiae as fermentative organism, although Escherichia coli, Zymomonas mobilis and Kluyveromyces marxianus, among others, were considered for second generation processes. For S. cerevisiae, key developments for fermentation of raw and cooked starch, as well as lignocellulose, include consolidated bioprocessing (CBP) where enzyme production for substrate hydrolysis and fermentation of released sugars are performed by a single organism. Further yeast developments required for second generation ethanol include engineering of xylose utilization capability, to increase yields from lignocellulose, and increasing the resistance of yeasts to inhibitory compounds formed during lignocellulose pretreatment prior to hydrolysis and fermentation. The present chapter will review the full scope of organism development for ethanol production, followed by examination of S. cerevisiae strain development for xylose utilization, CBP and hardening, as well as metabolic engineering, application of -omics technologies, and synthetic biology as examples of global efforts in organism development for ethanol production read more ...