Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/27/2004
Publication Date: 5/27/2004
Citation: Liu, S., Nichols, N.N., Dien, B.S., Cotta, M.A. 2004. Expression analysis of pyruvate decarboxylase genes from Zymobacter palmae and Sarcina ventriculi in Gram-positive lactic acid bacteria [abstract]. American Society for Microbiology. Paper No. O-099.
Technical Abstract: The current energy supply in the United States is heavily dependent on imported petroleum. The supply of fossil fuels is limited, and its consumption has been associated with a number of environmental problems. Because of this, exploration for other energy sources has become more important. The fact that ethanol can be produced through fermentation by microorganisms using renewable resources has made it as one of the more promising alternative energy sources. Currently, ethanol is produced via fermentation of corn starch derived glucose by yeasts. Expansion of the fermentative production of fuel alcohol to use additional substrates will require the development of new biocatalysts capable of using a variety of sugars, particularly those present in biomass. We have initiated a project to genetically modify fermentative lactic acid bacteria (LAB) to construct a new biocatalyst strain for ethanol production rather than lactic acid fermentation. Pyruvate decarboxylase (PDC) genes from Zymobacter palmae and Sarcina ventriculi were cloned and expressed in E. coli. The PDC genes were linked with several different Gram-positive promoters and transformed via a shuttle vector into LAB. Western blot analysis, using antiserum against an oligo-peptide for S. ventriculi PDC, confirmed the presence of PDC in transformed LAB. Preliminary data from these experiments indicated that the Gram-positive S. ventriculi PDC gene was active in LAB and catalyzed the conversion of pyruvate into acetaldehyde. The genetically engineered strains will be examined for ethanol and other metabolite products in flask fermentations. These strains will be evaluated for further genetic manipulations if necessary.