Formic acid effect on glucose fermentation by Saccharomyces spp to ethanol
Monday, April 28, 2014: 4:25 PM
Grand Ballroom F-G, lobby level (Hilton Clearwater Beach)
Cyprian E. Oshoma1, Darren Greetham1, Edward J. Louis2, Katherine Smart3, Trevor G. Phister4, Chris Powell1 and Chenyu Du1, (1)School of Biosciences, University of Nottingham, Nottingham, United Kingdom, (2)Centre for Genetic Architecture of complex traits, University of Leicester, Leicester, United Kingdom, (3)SAB Miller PLC, Woking, Surrey, United Kingdom, (4)PepsiCo Int., Leicester, NC, United Kingdom

  Present years have been devoted to the bioconversion of lignocelluloses biomass to bioethanol, as the better alternative liquid fuel to fossil fuels. However, one of the hurdles limiting successful bioconversion from the biomass to ethanol is the inhibiting compounds produced in the hydrolysates. These inhibitors hamper the efficient ethanol production due to their toxicity to microbes present in the fermentation.  Formic acid is one of the inhibitors released into the hydrolysates at a concentrations of 10 -30 mM, and much is yet to be known about the yeasts response to this acid. Spot plate and phenotypic microarray methods were used to assess formic acid tolerance of 11 Saccharomyces spp. Tolerance of Saccharomyces cerevisiae NCYC2592 and Saccharomyces arboricolus A07, B07 and C07 strains to formic acid were further investigated using mini fermentation techniques. Samples analysed in the course of fermentation were cell count, glucose concentration, ethanol and glycerol production.  During fermentation increase in formic acid in the media decreased cell count. Lower concentration of formic acid at 40mM increased ethanol production in NCYC2592. However, higher concentrations of the acid affected cell growth and ethanol production of the strains. Glycerol accumulation was equally affected in the fermentation profile, more was accumulated in the absent of formic acid in C07 strain. Overall result proved that lower concentration of formic acid in the media can increase bioethanol production. However, the mechanism of yeast response to formic acid is yet to be elucidated.