269702 Metabolic Engineering of Propionibacteria for n-Propanol Production

Tuesday, October 30, 2012: 2:42 PM
Westmoreland Central (Westin )
Ehab M Ammar and Shang-Tian Yang, William G. Lowrie Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, OH

Propionibacteria are widely used in industry for manufacturing of Swiss cheese, vitamin B12 and propionic acid. Little is known about their genetics and only a few reports are available on their metabolic engineering. Most previous metabolic engineering work on propionibacteria aimed at improving the fermentative production of either vitamin B12 or propionic acid. n-Propanol is a common solvent, intermediate in many industrial applications and a promising biofuel. No known microorganism can produce n-propanol naturally in sufficient quantities for manufacturing purposes. In this research, a bifunctional alcohol aldehyde deydrogenase (aad) was cloned from E. coli and overexpressed in propionibacteria. The mutant expressing the aad gene produced n-propanol from propionyl-CoA, which is the precursor for propionic acid biosynthesis. The production of n-propanol was limited by available NADH, which was improved significantly by using a mixture of different carbon sources. To our best knowledge, this is the first report on producing n-propanol by metabolically engineered propionibacteria, which offers a novel route to produce n-propanol from biomass.

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