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Appl. Environ. Microbiol., Nov 1996, 3978-3984, Vol 62, No. 11
MJ van der Maarel, M Jansen, R Haanstra, WG Meijer and TA Hansen
The initial step in the anaerobic degradation of the algal osmolyte
dimethylsulfoniopropionate (DMSP) in anoxic marine sediments involves
either a cleavage to dimethylsulfide and acrylate or a demethylation to
3-S-methylmercaptopropionate. Thus far, only one anaerobic bacterial strain
has been shown to carry out the demethylation, namely, Desulfobacterium sp.
strain PM4. The aims of the present work were to study how common this
property is among certain groups of anaerobic bacteria and to obtain
information on the affinities for DMSP of DMSP- demethylating strains.
Screening of several pure cultures of sulfate- reducing and acetogenic
bacteria showed that Desulfobacterium vacuolatum DSM 3385 and
Desulfobacterium niacini DSM 2059 are also able to demethylate DMSP; a very
slow demethylation of DMSP was observed with a salt-tolerant strain of
Eubacterium limosum. From a 10(5) dilution of intertidal sediment a new
marine DMSP-demethylating sulfate- reducing bacterium (strain WN) was
isolated. Strain WN was a short, gram-negative, nonmotile rod that grew on
betaine, sarcosine, palmitate, H2 plus CO2, and several alcohols, organic
acids, and amino acids. Extracts of betaine-grown cells had hydrogenase,
formate dehydrogenase, and CO dehydrogenase activities but no alpha-
ketoglutarate oxidoreductase activity, indicating the presence of the
acetyl coenzyme A-CO dehydrogenase pathway. Analysis of the 16S rRNA gene
sequence of strain WN revealed a close relationship with Desulfobacter
hydrogenophilus, Desulfobacter latus, and Desulfobacula toluolica. Strain
PM4 was shown to group with Desulfobacterium niacini. The K(m) of strain WN
for DMSP, as derived from substrate progress curves in cell suspensions,
was approximately 10 microM. A similar value was found for D. niacini PM4.
Copyright © 1996, American Society for Microbiology
Demethylation of dimethylsulfoniopropionate to 3-S- methylmercaptopropionate by marine sulfate-reducing bacteria
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
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