Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2000
Publication Date: N/A
Technical Abstract: Biomass from agricultural residues is a potential low-cost and environmentally advantageous feedstock for production of value added chemicals. We have developed a series of E. coli strains that convert sugars to either ethanol or L-lactate. The strains utilize a novel genetic strategy for enhanced production stability. The parental strains cannot grow fermentatively because of mutations in the lactate dehydrogenase and pyruvate formate lyase genes. We have transformed each parental strain with a plasmid encoding either the enzyme for L-lactate production (lactate dehydrogenase) or those for ethanol production (alcohol dehydrogenase and pyruvate decarboxylase). Each plasmid is positively selected for when the strains are cultured anaerobically because cells that lose the plasmid stop growing. When cultured anaerobically without antibiotics, either plasmid is retained by over 95% of the cells. In batch fermentations, yield of either ethanol or L-lactate are 90-93% of theoretical.