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Appl. Environ. Microbiol., Nov 1995, 3986-3991, Vol 61, No. 11
MP de Souza and DC Yoch
Dimethylsulfoniopropionate (DMSP) lyase enzymatically cleaves DMSP, an
algal metabolite, to produce acrylate, a proton, and dimethyl sulfide
(DMS), the most abundant volatile sulfur compound emitted from oceans. The
physiology of DMS production by DMSP lyase was studied in vivo in an
Alcaligenes-like organism, strain M3A, a salt marsh bacterial isolate, and
in a marine strain, Pseudomonas doudoroffii. Enzymes from both strains were
induced at optimum rates by 1 mM DMSP and vigorous aeration. P. doudoroffii
was very sensitive to continued aeration and lost activity rapidly; the
enzyme was more stable when aeration ceased. In addition to DMSP, acrylate
and several of its analogs acted as inducers of DMSP lyase in Alcaligenes
sp. strain M3A but not in P. doudoroffii. Turnover of DMSP by P.
doudoroffii was enhanced by 3.5% NaCl or seawater, whereas the Alcaligenes
sp. strain M3A enzyme was not salt dependent and salt did not greatly
affect its activity. The pH profile showed two peaks of DMSP lyase activity
(6.5 and 8.8) for Alcaligenes sp. strain M3A and a single peak at pH 8 for
P. doudoroffii. Enzyme activity in both organisms was inhibited by
methyl-3-mercaptopropionate and homocysteine. Cyanide, azide and
p-chloromercuribenzoate inhibited only the P. doudoroffii DMSP lyase. The
apparent K(infm) values for DMSP for cell cultures of Alcaligenes sp.
strain M3A and P. doudoroffii were ca. 2 mM and <20 (mu)M, respectively.
The differences in the physiology of DMSP metabolism in these two bacterial
isolates may enable them to exist in diverse ecological niches.
Copyright © 1995, American Society for Microbiology
Comparative Physiology of Dimethyl Sulfide Production by Dimethylsulfoniopropionate Lyase in Pseudomonas doudoroffii and Alcaligenes sp. Strain M3A
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208
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