Affiliation:
1. Department of Chemistry and Biochemistry, and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309-0215
Abstract
ABSTRACT
There is current interest in biological sources of acetone, a volatile organic compound that impacts atmospheric chemistry. Here, we determined that leucine-dependent acetone formation is widespread in the
Vibrionaceae
. Sixteen
Vibrio
isolates, two
Listonella
species, and two
Photobacterium angustum
isolates produced acetone in the presence of
l
-leucine.
Shewanella
isolates produced much less acetone. Growth of
Vibrio splendidus
and
P. angustum
in a fermentor with controlled aeration revealed that acetone was produced after a lag in late logarithmic or stationary phase of growth, depending on the medium, and was not derived from acetoacetate by nonenzymatic decarboxylation in the medium.
l
-Leucine, but not
d
-leucine, was converted to acetone with a stoichiometry of approximately 0.61 mol of acetone per mol of
l
-leucine. Testing various potential leucine catabolites as precursors of acetone showed that only α-ketoisocaproate was efficiently converted by whole cells to acetone. Acetone production was blocked by a nitrogen atmosphere but not by electron transport inhibitors, suggesting that an oxygen-dependent reaction is required for leucine catabolism. Metabolic labeling with deuterated (isopropyl-d
7
)-
l
-leucine revealed that the isopropyl carbons give rise to acetone with full retention of deuterium in each methyl group. These results suggest the operation of a new catabolic pathway for leucine in vibrios that is distinct from the 3-hydroxy-3-methylglutaryl-coenzyme A pathway seen in pseudomonads.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
23 articles.
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