Affiliation:
1. Department of Botany and Microbiology, University of Oklahoma, 770 Van Vleet Oval, Norman, Oklahoma 73019
Abstract
The effects of organic acid anions on the growth of
Syntrophomonas wolfei
was determined by varying the initial concentration of the acid anion in the medium. The addition of 15 mM acetate decreased the growth rate of a butyrate-catabolizing coculture containing
Methanospirillum hungatei
from 0.0085 to 0.0029 per hour. Higher initial acetate concentrations decreased the butyrate degradation rate and the yield of cells of
S. wolfei
per butyrate degraded. Inhibition was not due to the counter ion or the effect of acetate on the methanogen. Initial acetate concentrations above 25 mM inhibited crotonate-using pure cultures and cocultures of
S. wolfei
. Benzoate and lactate inhibited the growth of
S. wolfei
on crotonate in pure culture and coculture. Lactate was an effective inhibitor of
S. wolfei
cultures at concentrations greater than 10 mM. High concentrations of acetate and lactate altered the electron flow in crotonate-catabolizing cocultures, resulting in the formation of less methane and more butyrate and caproate. The inclusion of the acetate-using methanogen,
Methanosarcina barkeri
, in a methanogenic butyrate-catabolizing coculture increased both the yield of
S. wolfei
cells per butyrate degraded and the efficacy of butyrate degradation. Butyrate degradation by acetate-inhibited cocultures occurred only after the addition of
Methanosarcina barkeri
. These results showed that the metabolism of
S. wolfei
was inhibited by high levels of organic acid anions. The activity of acetate-using methanogens is important for the syntrophic degradation of fatty acids when high levels of acetate are present.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
48 articles.
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