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Poster Presentation 2-24
Production of Lactic Acid from Lignocellulosic Hydrolysates by Escherichia coli Mutants
Edward St.Martin, Cynthia Sanville Millard, James Frank and Mark Donnelly
Argonne National Laboratory, Chemical and Biological Technology Section 9700 South Cass Avenue, Argonne, IL 60439-4815
Telephone: (630) 252-5784; Fax: (630) 252-9281; E-mail: estmartin@anl.gov
Commercial production of lactic acid is generally catalyzed by strains or consortia of Lactobacillus. We have developed mutants of Escherichia coli lacking pyruvate:formate lyase that produce primarily lactic acid from the fermentation of glucose. These mutant strains of E. coli are prototrophic, grow vigorously, and produce lactic acid as efficiently as the commercial Lactobacillus strains, yielding product concentrations of 100 g/L at productivities over 2 g/L/h. Unlike the heterotrophic Lactobacillus strains, the E. coli strains also produce lactic acid efficiently from crude lignocellulosic hydrolysates lacking complex additives, allowing the use of this potentially less expensive feedstock. Xylose and arabinose both were converted to lactic acid. The E. coli mutants also produce succinic acid efficiently in defined media, generating fermentation broths of higher purity than occurs in existing fermentations potentially reducing purification costs.
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