Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2005
Publication Date: 8/25/2005
Citation: Liu, S., Dien, B.S., Cotta, M.A., Bischoff, K.M., Hughes, S.R. 2005. Lactobacillus brevis: a potential biocatalyst for lignocellulosic biomass to ethanol [abstract]. Society of Industrial Microbiology. Paper #P05.
Technical Abstract: Lignocellulosic biomass offers a plentiful alternative feedstock to grains and sugar cane for the production of fuel ethanol. Lignocellulose contains multiple sugars, which precludes the use of industrial Saccharomyces strains. While there have been major strides made in developing recombinant strains capable of fermenting these complex sugar mixtures selectively to ethanol, further strain development is needed for the field to advance. Previously published reports indicate that Lactobacillus brevis is a robust microorganism well adapted for industrial type fermentations, with representative strains capable of using sugar mixtures similar to those derived from lignocellulosic biomass. We decided to explore in more detail the potential use of L. brevis for ethanol production. L. brevis strain ATCC 367 produced approx. 20 g/l of ethanol when grown on MRS medium containing 60 g/l glucose in pH-controlled fermentations. The only other major fermentation product was lactic acid (34 g/l). L. brevis produces ethanol via the phosphoketolyase pathway. A key enzyme in the pathway is alcohol dehydrogenase, encoded by adhE, which is believed to be a bifunctional enzyme that contains both acetaldehyde dehydrogenase and alcohol dehydrogenase activities. The adhE gene from L. brevis strain ATCC 367 was isolated and characterized, and the gene was expressed in E. coli strain NZN111for the anaerobic production of ethanol.