title: Pathways of propionate degradation by enriched methanogenic cultures.
abstract: A mixed methanogenic culture was highly enriched in a growth medium containing propionate as the sole organic carbon and energy source. With this culture, the pathways of propionate degradation were studied by use of C-radiotracers. Propionate was first metabolized to acetate, carbon dioxide, and hydrogen by nonmethanogenic organisms. Formate was not excreted. The carbon dioxide originated exclusively from the carboxyl group of propionate, whereas both [2-C]- and [3-C]propionate lead to the production of radioactive acetate. The methyl and carboxyl groups of the acetate produced were equally labeled, regardless of whether [2-C]- or [3-C]propionate was used. These observations suggest that in the culture, propionate was degraded through a randomizing pathway.
authors.affiliation: Swiss Federal Institute of Technology, Zürich, and Federal Institute for Water Resources and Water Pollution Control, CH-8600 Dubendorf, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Koch
authors.forename: J
authors.initials: J
authors.lastname: Dolfing
authors.forename: K
authors.initials: K
authors.lastname: Wuhrmann
authors.forename: A J
authors.initials: AJ
authors.lastname: Zehnder