Affiliation:
1. National Animal Disease Laboratory, Animal Disease and Parasite Research Division, U.S. Department of Agriculture, Ames, Iowa
Abstract
Certain anaerobic ruminal bacteria synthesize the leucine carbon skeleton by use of a pathway different from that described in other microorganisms. These organisms carboxylate the intact carbon skeleton of isovalerate, synthesizing leucine-
2
-
C
14
from isovalerate-
1
-
C
14
. Strains of
Bacteroides ruminicola
and
Peptostreptococcus elsdenii
were like
Ruminococcus flavefaciens
in that they incorporated appreciable amounts of C
14
from isovalerate-
1
-
C
14
into cellular protein and in that the only labeled amino acid found was leucine. The specific activity of β-isopropylmalate dehydrogenase in extracts from
R. flavefaciens
and from the mixed bacterial population from the rumen was very low as compared with the specific activity of this enzyme in extracts from
Escherichia coli
. This suggests that the pathway of leucine biosynthesis that operates in many aerobic and facultative microorganisms is not the major pathway in rumen bacteria. This was supported by the finding that after fermentation of whole rumen contents with acetate-
2
-
C
14
, leucine from the bacterial cells had a specific activity lower than one would expect if acetate was incorporated directly into carbons 1 and 2 of leucine.
Publisher
American Society for Microbiology
Subject
General Pharmacology, Toxicology and Pharmaceutics,General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine
Cited by
12 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献