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11.
Henk M. Jonkers Michael Jansen Marc J. E. C. Van der Maarel H. Van Gemerden 《Archives of microbiology》1999,172(3):150-156
This is the first report describing the complete oxidation of dimethyl sulfide (DMS) to sulfate by an anoxygenic, phototrophic
purple sulfur bacterium. Complete DMS oxidation was observed in cultures of Thiocapsa roseopersicina M11 incubated under oxic/light conditions, resulting in a yield of 30.1 mg protein mmol–1. No oxidation of DMS occurred under anoxic/light conditions. Chloroform, methyl butyl ether, and 3-amino-1,2,4-triazole,
which are specific inhibitors of aerobic DMS oxidation in thiobacilli and hyphomicrobia, did not affect DMS oxidation in strain
M11. This could be due to limited transport of the inhibitors through the cell membrane. The growth yield on sulfide as sole
electron donor was 22.2 mg protein mmol–1 under anoxic/light conditions. Since aerobic respiration of sulfide would have resulted in yields lower than 22 mg protein
mmol–1, the higher yield on DMS under oxic/light conditions suggests that the methyl groups of DMS have served as an additional
carbon source or as an electron donor in addition to the sulfide moiety. The kinetic parameters V
max and K
m for DMS oxidation under oxic/light conditions were 12.4 ± 1.3 nmol (mg protein)–1 min–1 and 2 μM, respectively. T. roseopersicina M11 also produced DMS by cleavage of dimethylsulfoniopropionate (DMSP). Specific DMSP cleavage rates increased with increasing
initial substrate concentrations, suggesting that DMSP lyase was only partly induced at lower initial DMSP concentrations.
A comparison of T. roseopersicina strains revealed that only strain M11 was able to oxidize DMS and cleave DMSP. Both strain M11 and strain 5811 accumulated
DMSP intracellularly during growth, while strain 1711 showed neither of these characteristics. Phylogenetic comparison based
on 16S rRNA gene sequence revealed a similarity of 99.0% between strain M11 and strain 5811, and 97.6% between strain M11
and strain 1711. DMS and DMSP utilization thus appear to be strain-specific.
Received: 26 March 1999 / Accepted: 18 June 1999 相似文献
12.
Abstract Demethylation and cleavage of dimethylsulfoniopropionate (DMSP) was measured in three different types of intertidal marine sediments: a cyanobacterial mat, a diatom-covered tidal flat and a carbonate sediment. Consumption rates of added DMSP were highest in cyanobacterial mat slurries (59 μmol DMSP 1−1 ) and lower in slurries from a diatom mat and a carbonate tidal sediment (24 and 9 μmol DMSP 1−1 h−1 , respectively). Dimethyl sulfide (DMS) and 3-mercaptopropionate (MPA) were produced simultaneously during DMSP consumption, indicating that cleavage and demethylation occurred at the same time. Viable counts of DMSP-utilizing bacteria revealed a population of 2 × 107 cells cm−3 sediment (90% of these cleaved DMSP to DMS, 10% demethylated DMSP to MPA) in the cyanobacterial mat, 7 × 105 cells cm−3 in the diatom mat (23% cleavers, 77% demethylators), and 9 × 104 cells cm−3 (20% cleavers and 80% demethylators) in the carbonate sediment. In slurries of the diatom mat, the rate of MPA production from added 3-methiolpropionate (MMPA) was 50% of the rate of MPA formation from DMSP. The presence of a large population of demethylating bacteria and the production of MPA from DMSP suggest that the demethylation pathway, in addition to cleavage, contributes significantly to DMSP consumption in coastal sediments. 相似文献
13.
The relation between net dimethyl sulfide (DMS) production and changes in near surface (0-5 mm) oxygen concentrations in a sea grass (Zostera noltii Hornem)-covered intertidal sediment ecosystem was examined during a diel cycle. Sediment covered with Zostera was found to be more oxygenated than uncovered sediment during the period of photosynthesis. This phenomenon was probably caused by radial oxygen loss of the Zostera root-rhizome system. The population sizes of the three functional groups of microbes mainly responsible for the concentration of DMS, the dimethylsulfoniopropionate (DMSP)-demethylating, DMSP-cleaving and DMS-oxidizing bacteria, were quantified by most probable number (MPN) methodologies. Sediments with Zostera supported substantially higher populations of both aerobic (149x10(6) cm(-3) DMSP-utilizing and 0.4x10(6) cm(-3) DMS-oxidizing) and anaerobic (43x10(6) cm(-3) DMSP-utilizing and 0.4x10(6) cm(-3) DMS-oxidizing) microorganisms than sediments without Zostera (DMSP-utilizing aerobes and anaerobes both 2x10(6) cm(-3) and DMS-oxidizing aerobes and anaerobes both 0.2x10(6) cm(-3)). Experiments conducted with sediment cores and sediment slurries suggested that the net production of DMS in these sediments was significantly lower during oxic periods than during anoxic periods. Intact sediment cores with and without Zostera produced DMS when incubated under anoxic/dark conditions (97.0 and 53.6 nmol DMS m(-2) h(-1), respectively), while oxic/light-incubated cores did not produce detectable amounts of DMS. In addition, kinetic parameter values (V(max) and K(m)) for DMSP degradation in cell suspensions of isolated DMSP-demethylating and DMSP-cleaving bacteria were measured and compared to documented values for other strains. Both V(max) and K(m) values for DMSP-demethylating organisms were found to be relatively low (14.4-20.1 nmol DMSP mg protein(-1) min(-1) and 4.1-15.5 μM, respectively) while these parameter values varied widely in the group of the DMSP-cleaving organisms (6.7-1000 nmol DMSP mg protein(-1) min(-1) and 2-2000 μM, respectively). It was hypothesized that a diel rhythm in DMS emission occurred, with a relatively low net production during the day and a high net production during the night. Environmental changes which result in increased anoxic conditions in coastal sediments, such as an increase in eutrophication, may therefore result in increased atmospheric DMS emission rates. 相似文献
14.
Tetrahydrofolate was shown to function as a methyl acceptor in the anaerobic demethylation of dimethylsulfoniopropionate
to methylthiopropionate in cell extracts of the sulfate-reducing bacterium strain WN. Dimethylsulfoniopropionate-dependent
activities were 0.56 μmol methyltetrahydrofolate min–1 (mg protein)–1 and were higher than required to explain the growth rate of strain WN on dimethylsulfoniopropionate. The reaction did not
require ATP or reductive activation by titanium(III)-nitrilotriacetic acid. Preincubation of the extract under air significantly
decreased the activity (35% loss in 3 h). Three other dimethylsulfoniopropionate-demethylating sulfate reducers, Desulfobacterium niacini, Desulfobacterium vacuolatum, and Desulfobacterium strain PM4, had dimethylsulfoniopropionate:tetrahydrofolate methyltransferase activities of 0.16, 0.05, and 0.24 μmol min–1 (mg protein)–1, respectively. No methyltransferase activity to tetrahydrofolate was found with betaine as a substrate, not even in extracts
of betaine-grown cells of these sulfate reducers. Dimethylsulfoniopropionate demethylation in cell extracts of strain WN was
completely inhibited by 0.5 mM propyl iodide; in the light, the inhibition was far less strong, indicating involvement of
a corrinoid-dependent methyltransferase.
Received: 24 June 1997 / Accepted: 29 August 1997 相似文献
15.
Abstract The metabolism of the methylated osmolytes glycine betaine (GB) and dimethylsulfoniopropionate (DMSP) was studied in a bacterium (strain MD 14–50) isolated from a colony of the cyanobacterium Trichodesmium . MD 14–50 when grown on DMSP cleaved dimethylsulfide (DMS) from DMSP and oxidized acrylate. In contrast to DMSP, GB was metabolized by sequential N-demethylations. Low concentrations (100 μM) of DMSP or GB allowed the growth of MD 14–50 on glucose at higher salinities than in their absence. At elevated salinities, DMSP was accumulated intracellularly with less catabolism and DMS production. Thus, DMSP and GB were catabolized by different mechanisms but functioned interchangeably as osmolytes. 相似文献
16.
Cleavage of dimethylsulfoniopropionate and reduction of acrylate by Desulfovibrio acrylicus sp. nov.
Marc J. E. C. van der Maarel S. van Bergeijk A. F. van Werkhoven A. M. Laverman W. G. Meijer Wytze T. Stam T. A. Hansen 《Archives of microbiology》1996,166(2):109-115
From anoxic intertidal sediment, a dimethylsulfoniopropionate (DMSP)-cleaving anaerobe (strain W218) was isolated that reduced
the acrylate formed to propionate. The bacterium was vibrio- to rod-shaped and motile by means of multiple polar flagella.
It reduced sulfate, thiosulfate, and acrylate, and used lactate, fumarate, succinate, malate, pyruvate, ethanol, propanol,
glycerol, glycine, serine, alanine, cysteine, hydrogen, and formate as electron donors. Sulfate and acrylate were reduced
simultaneously; growth with sulfate was faster than with acrylate. Extracts of cells grown in the presence of DMSP contained
high DMSP lyase activities (9.8 U/mg protein). The DNA mol% G+C was 45.1. On the basis of its characteristics and the 16S
rRNA gene sequence, strain W218 was assigned to a new Desulfovibrio species for which the name Desulfovibrio acrylicus is proposed. A variety of other sulfate-reducing bacteria (eight of them originating from a marine or saline environment
and five from other environments) did not reduce acrylate.
Received: 22 March 1996 / Accepted: 8 May 1996 相似文献
17.
C. Vogt Andreas Rabenstein Jörg Rethmeier Ulrich Fischer 《Archives of microbiology》1998,169(3):263-266
By the method of cold alkali hydrolysis, 29 marine benthic cyanobacteria were screened for production of alkali-labile precursors
of dimethyl sulfide (DMS) including dimethylsulfoniopropionate (DMSP), a compound of significant importance in marine environments.
Concentrations of DMS precursors ranged from undetectable to 0.8 mmol (g Chl a)–1. The data correspond to some previous investigations concerning DMSP content of marine cyanobacteria and suggest that marine
benthic cyanobacteria are only minor producers of DMSP.
Received: 3 July 1997 / Accepted: 21 October 1997 相似文献