Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2007
Publication Date: 3/1/2008
Citation: Liu, S., Skinner-Nemec, K.A., Leathers, T.D. 2008. Lactobacillus buchneri strain NRRL B-30929 converts a concentrated mixture of C5 and C6 sugars into ethanol and other products. Journal of Industrial Microbiology and Biotechnology. 35:75-81. Interpretive Summary: New and improved biocatalysts are needed to convert biomass into valuable fuels and chemicals. A novel lactic acid bacterium was isolated as a contaminant of a fuel ethanol production facility. Unlike conventional yeast, this organism uses a mixture of five-carbon and six-carbon sugars commonly found in agricultural residues and other lignocellulosic biomass for production of ethanol and other chemicals, including an antimicrobial peptide. Results will be valuable to researchers developing new biocatalysts for biomass-based biorefinery platforms.
Technical Abstract: Lactobacillus buchneri strain NRRL B-30929 was isolated from a fuel ethanol production facility. This heterofermentative, facultative anaerobe can utilize xylose as a sole carbon source and tolerates up to 12% ethanol. Carbohydrate utilization (API, Biomerieux) and Phenotype Microarrays™ (PM, Biolog) analyses indicated that the strain is able to metabolize a broad spectrum of carbon sources including various monosaccharides (C5 & C6), disaccharides, and oligosaccharides, with better rate under anaerobic conditions. In pH-controlled bioreactors, the bacterium consumed xylose and glucose simultaneously at high concentrations (12.5% each, pH 6.0). The major fermentation products are lactate, acetate, and ethanol. The strain ferments glucose alone (10%, pH 4.0) into lactate and ethanol with a molar ratio of 1.03 :1. Another interesting product recovered in the fermentation broth is a 3.5 kDa peptide which was identified as buchnericin. The simultaneous production of lactate, ethanol, and buchnericin from lignocellulosic biomass has potential application in bio-based refinery platforms.