González, J.M., R.P. Kiene and M.A. Moran. In Press. Transformations of sulfur compounds by an abundant lineage of marine bacteria in the alpha-subclass of the Proteobacteria. Applied and Environmental Microbiology.
      Members of a group of marine bacteria that is numerically important in
    coastal seawater and sediments were characterized with respect to their
    ability to transform organic and inorganic sulfur compounds.  Fifteen
    strains representing the Roseobacter group (a phylogenetic cluster of
    marine bacteria in the alpha-subclass of Proteobacteria) were
    isolated from seawater, primarily from the southeastern U.S.  Although over
    half the isolates were obtained without any selection for sulfur metabolism,
    all were able to degrade the sulfur containing osmolyte dimethylsulfoniopropionate 
    (DMSP), with production of dimethylsulfide (DMS).  Five isolates also 
    degraded DMSP with production of methanethiol, indicating the unusual 
    occurrence of both cleavage and demethylation pathways for DMSP in the same 
    organism.  Five isolates were able to reduce DMSO to DMS, and several also 
    degraded DMS and methanethiol.  Sulfite oxygenase activity and methanesulfonic 
    acid oxygenase activity were also present for some of the isolates.  The 
    ability to incorporate reduced sulfur in DMSP and methanethiol into cellular 
    material was studied in one of the isolates.  A group specific 16S rRNA probe 
    indicated that uncultured bacteria in the Roseobacter group increase 
    in relative abundance in seawater enriched with DMSP or DMS.  Because this 
    group typically accounts for >10% of the 16S rDNA pool in coastal seawater 
    and sediments of the southern U.S., clues about its potential biogeochemical 
    role are of particular interest.  Studies of culturable representatives suggest 
    that the group could mediate a number of steps in the cycling of both organic 
    and inorganic forms of sulfur in marine environments.