Previous Article | Next Article ![]()
Applied and Environmental Microbiology, December 2005, p. 7650-7660, Vol. 71, No. 12
0099-2240/05/$08.00+0 doi:10.1128/AEM.71.12.7650-7660.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Marine Microbiology, Department of Biology and Environmental Sciences, University of Kalmar, SE-39182 Kalmar, Sweden,1 Institut de Ciències del Mar-CMIMA (CSIC), ES-08003 Barcelona, Catalonia,2 Department of Microbiology and Cell Biology, University of La Laguna, ES-38206 La Laguna, Tenerife, Spain,3 Department of Marine Sciences, University of South Alabama, Mobile, Alabama 36688, and Dauphin Island Sea Lab, Dauphin Island, Alabama 36528,4 Department of Marine Sciences, University of Georgia, Athens, Georgia 306025
Received 27 May 2005/ Accepted 22 July 2005
Processing of the phytoplankton-derived organic sulfur compound dimethylsulfoniopropionate (DMSP) by bacteria was studied in seawater microcosms in the coastal Gulf of Mexico (Alabama). Modest phytoplankton blooms (peak chlorophyll a [Chl a] concentrations of
2.5 µg liter1) were induced in nutrient-enriched microcosms, while phytoplankton biomass remained low in unamended controls (Chl a concentrations of
0.34 µg liter1). Particulate DMSP concentrations reached 96 nM in the enriched microcosms but remained approximately 14 nM in the controls. Bacterial biomass production increased in parallel with the increase in particulate DMSP, and nutrient limitation bioassays in the initial water showed that enrichment with DMSP or glucose caused a similar stimulation of bacterial growth. Concomitantly, increased bacterial consumption rate constants of dissolved DMSP (up to 20 day1) and dimethylsulfide (DMS) (up to 6.5 day1) were observed. Nevertheless, higher DMSP S assimilation efficiencies and higher contribution of DMSP to bacterial S demand were found in the controls compared to the enriched microcosms. This indicated that marine bacterioplankton may rely more on DMSP as a source of S under oligotrophic conditions than under the senescence phase of phytoplankton blooms. Phylogenetic analysis of the bacterial assemblages in all microcosms showed that the DMSP-rich algal bloom favored the occurrence of various Roseobacter members, flavobacteria (Bacteroidetes phylum), and oligotrophic marine Gammaproteobacteria. Our observations suggest that the composition of the bacterial assemblage and the relative contribution of DMSP to the overall dissolved organic sulfur/organic matter pool control how efficiently bacteria assimilate DMSP S and thereby potentially divert it from DMS production.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»