Microbial removal of acetate selectively from sugar mixtures
- 203 Downloads
Acetic acid is an unavoidable constituent of the biomass hydrolysates generated from acetylated hemicellulose and lignin, and acetate affects the performance of microbes used to convert these hydrolysates into biofuels or other biochemicals. In this study, acetate was selectively removed from synthetic mixtures of glucose and xylose using metabolically engineered Escherichia coli strains having mutations in the glucose phosphotransferase system (PTS) genes (ptsG, manZ, crr), glucokinase (glk), and xylose (xylA). In batch culture, ALS1060 (ptsG manZ glk xylA) consumed exclusively acetate to depletion, and then consumed the two sugars only at a very slow rate (a growth rate of about 0.01 h−1). We also examined the effects of an additional knockout of either malX, fruA, fruB, bglF, or crr, genes that are involved in other PTSs, and a batch process using KD840 (ptsG manZ glk crr xylA) demonstrated a further reduction in glucose or xylose consumption by E. coli. These results demonstrate the feasibility of using a substrate-selective approach for the pre-treatment of biomass hydrolysate for microbial processes.
KeywordsBiomass hydrolysate Xylose Glucose Ethanol Acetate
This project was supported by the Consortium for Plant Biotechnology Research (CPBR), the National Science Foundation (CBET-0929893), and the Georgia Experiment Station. We also acknowledge S. A. Lee and R. Altman for technical assistance.
- 12.Fonseca BR, Moutta RO, Ferraz FO, Vieira ER, Nogueira AS, Baratella BF, Rodrigues LC, Hou-Rui Z, Silva SS (2011) Biological detoxification of different hemicellulosic hydrolysates using Issatchenkia occidentalis CCTCC M 206097 yeast. J Ind Microbiol Biotechnol 38:199–207Google Scholar
- 27.Sarkanen KV, Ludwig CH (1971) Lignins: occurrence, formation, structure and reactions. Wiley-Interscience, New York, pp 345–372Google Scholar