Sequential Method for the Field Determination of Nanomolar Concentrations of Dimethyl Sulfoxide in Natural Waters

Vila‐Costa²,

Alonso‐Sáez³

et al. 2009

Aquat. Microb. Ecol.

The contribution of dimethylsulfoniopropionate (DMSP) to the fluxes of carbon and sulfur through phytoplankton and bacterioplankton was investigated throughout an annual cycle in the Blanes Bay Microbial Observatory (coastal NW Mediterranean). DMSP accounted for 0.3 to 7% of biovolume-estimated phytoplankton carbon and 4 to 93% of calculated phytoplankton sulfur, with higher contributions in 'summer' (highly irradiated, oligotrophic waters, May to September) and lower in 'winter' (October to April). DMSP biosynthesis rates accounted for 0.8 to 7% of carbon fixation and 11 to 88% of sulfur assimilation through primary production, with slightly higher shares in summer. Upon release from the algal cells, DMSP supplied 0.5 to 6% of the total carbon demand of heterotrophic bacteria, and 3 to 100% of the sulfur demand over the year. Uncertainties associated with these calculations are due to a scarce knowledge of C:S ratios in marine bacteria. Bacterial DMSP-sulfur assimilation (measured with 35 S-DMSP) was positively correlated with bacterial heterotrophic production rates (measured with 3 H-leucine). In summer waters, characterized by higher ratios of particulate DMSP to chlorophyll a (DMSP p :chl a), DMSP-sulfur assimilation by bacteria was higher and contributed a larger share of the bacterial sulfur demand. We propose that the DMSP:chl a ratio is a good indicator of the relative role of DMSP in the carbon and sulfur fluxes through the first levels of the planktonic food web.

Section: Methodsmentioning

confidence: 99%

Annual DMSP contribution to S and C fluxes through phytoplankton and bacterioplankton in a NW Mediterranean coastal site

Vila‐Costa²,

Alonso‐Sáez³

et al. 2009

Aquat. Microb. Ecol.

“…Concentrations of DMSP, DMS, and dimethyl sulfoxide (DMSO) were determined for the surface water samples (12 out of 42 samples) following reaction, purge, cryotrapping, and sulfur-specific gas chromatography procedures described by Simó et al (43). Dissolved compounds were measured in GF/Ffiltered seawater, and the filters were treated for determination of particulate DMSP and DMSO.…”

Section: Methodsmentioning

confidence: 99%

Bacterial Community Structure Associated with a Dimethylsulfoniopropionate-Producing North Atlantic Algal Bloom

González

Massana

et al. 2000

Appl Environ Microbiol

398

353

The bacteria associated with oceanic algal blooms are acknowledged to play important roles in carbon, nitrogen, and sulfur cycling, yet little information is available on their identities or phylogenetic affiliations. Three culture-independent methods were used to characterize bacteria from a dimethylsulfoniopropionate (DMSP)-producing algal bloom in the North Atlantic. Group-specific 16S rRNA-targeted oligonucleotides, 16S ribosomal DNA (rDNA) clone libraries, and terminal restriction fragment length polymorphism analysis all indicated that the marine Roseobacter lineage was numerically important in the heterotrophic bacterial community, averaging >20% of the 16S rDNA sampled. Two other groups of heterotrophic bacteria, the SAR86 and SAR11 clades, were also shown by the three 16S rRNA-based methods to be abundant in the bloom community. In surface waters, the Roseobacter, SAR86, and SAR11 lineages together accounted for over 50% of the bacterial rDNA and showed little spatial variability in abundance despite variations in the dominant algal species. Depth profiles indicated that Roseobacter phylotype abundance decreased with depth and was positively correlated with chlorophyll a, DMSP, and total organic sulfur (dimethyl sulfide plus DMSP plus dimethyl sulfoxide) concentrations. Based on these data and previous physiological studies of cultured Roseobacter strains, we hypothesize that this lineage plays a role in cycling organic sulfur compounds produced within the bloom. Three other abundant bacterial phylotypes (representing a cyanobacterium and two members of the ␣ Proteobacteria) were primarily associated with chlorophyll-rich surface waters of the bloom (0 to 50 m), while two others (representing Cytophagales and ␦ Proteobacteria) were primarily found in deeper waters (200 to 500 m).The bacterial communities associated with oceanic algal blooms play critical roles in carbon and nitrogen cycling through their influence on the formation and fate of dissolved organic matter (4, 7), nutrient availability (24), sinking flux (45), and many other processes. In blooms dominated by algal species that produce dimethylsulfoniopropionate (DSMP), bloom-associated bacteria also play an important role in organic-sulfur cycling. Degradation of DMSP by marine bacteria is one of the primary routes for the formation of dimethyl sulfide (DMS), a volatile sulfur compound that influences global climate through effects on backscatter and cloud formation (6). Recent studies have suggested that marine bacteria may control DMS formation through the expression of a competing pathway that routes the sulfur in DMSP through methanethiol (MeSH) rather than to DMS (21, 27, 46). New evidence is pointing to one particular lineage of marine bacteria as a key participant in DMSP biogeochemistry in the ocean. Both culture-independent (i.e., 16S rRNA-based) and culture-dependent studies indicate that members of the ␣ Proteobacteria belonging to the Roseobacter lineage are abundant in coastal and open-ocean environments (15,17,18), where they ar...

“…DMS, DMSP and DMSO were analyzed following methods of reaction, purge, cryogenic trapping and sulfur-specific gas chromatography described elsewhere (Simó et al 1996(Simó et al , 1998b. Analytical error was ≤10% (coefficient of variation) and detection limit was 3 pmol S. Compounds measured in 5 to 50 ml aliquots of seawater filtered through Whatman GF/F glass fiber filters (nominal pore size: 0.7 µm) were operationally considered as 'dissolved'.…”

Section: Methodsmentioning

confidence: 99%

Biological turnover of DMS, DMSP and DMSO in contrasting open-sea waters

Pedrós-Alió²,

Malin³

et al. 2000

Mar. Ecol. Prog. Ser.

118

Speciation and turnover of the methylated sulfur compounds dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) were studied in waters of the open western Mediterranean, the near-coastal North Sea and the subpolar North Atlantic, with chlorophyll a concentrations spanning 2 orders of magnitude (0.12 to 13 µg l -1 ). Particulate DMSP (DMSP p : 5 to 340 nM) was the predominant pool in most waters. Dissolved and particulate dimethyl sulfoxide were also found at significant concentrations (DMSO d : 2 to 25 nM, DMSO p : 3 to 16 nM). Biological DMSP consumption rates were estimated from the time course of total (dissolved + particulate) DMSP concentration in dark incubations. Dimethyl sulfide production and consumption rates were determined by the 'inhibitor addition' method. High DMS production and consumption rates were found during a bloom of Phaeocystis sp. in North Sea waters. In all samples, turnover time constants for total DMSP and DMS were of the same order, ranging from 0.7 to 5.4 and from 0.3 to 2.1 d, respectively. DMS formation was the fate for 9 to 96% of the DMSP consumed. Use of chloroform as an inhibitor gave estimates of DMS production and consumption rates approximately 70% higher than those obtained with dimethyl disulfide and dimethyl selenide. In some incubation experiments, the time course of DMSO concentration has been followed along with DMS and DMSP for the first time. Evidence for active biological cycling (production and consumption) of DMSO in seawater is presented. KEY WORDS: Dimethyl sulfide · Dimethylsulfoniopropionate · Dimethyl sulfoxide · DMS · DMSP · DMSO · Inhibitor technique · Bacteria · Phytoplankton Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 203: [1][2][3][4][5][6][7][8][9][10][11] 2000 Hence, because of its biogeochemical, ecological and biochemical implications, interest in methylated sulfur is currently increasing and diversifying . In the epipelagic marine environment, methylated sulfur undergoes a maze of transformation processes involving a number of chemical species, including DMSP, DMS, dimethyl sulfoxide (DMSO) and methanethiol (CH 3 SH). Increasing understanding of methylated sulfur cycling requires combining the study of individual production and turnover processes relative to the distribution of the particulate and dissolved pools of these different compounds.DMSP release from phytoplankton and its degradation involves all levels of the food web, from viruses and bacteria to grazers (Dacey & Wakeham 1986, Belviso et al. 1990, Kiene & Bates 1990, Stefels & van Boekel 1993). Cleavage of DMSP by bacterial and algal DMSP-lyases is considered to be the main source of aqueous DMS, which in turn can be utilized by bacteria (e.g. Kiene & Bates 1990, Taylor 1993, Wolfe & Kiene 1993a. Alternative routes for microbial DMSP utilization exist, involving either uptake as osmotic solute (Wolfe 1996), double demethylation or demethylation and demethiolation to CH 3 SH (Taylor & Gilch...