González, J.M. and M.A. Moran. 1997. Numerical dominance of a group of marine bacteria in the alpha-subclass of Proteobacteria in coastal seawater. Appl. Environ. Microbiol. 63:4237-4242.
         A cluster of marine bacteria within the alpha-3 subclass of
    Proteobacteria was found to account for up to 28% of the 16S rDNA
    sequences in seawater samples from the coast of the southeastern U.S.  Two
    independent oligonucleotide probes targeting 16S rDNA of this "marine alpha"
    cluster indicate that the group dominates bacterioplankton communities in
    estuarine and nearshore regions of the southeastern U.S. coast.  Marine
    alpha bacteria decline predictably in abundance with decreasing salinity
    along estuarine transects and are not detectable in low salinity
    (5o/oo) or freshwater samples.  Sequences of 16S rDNA obtained
    from seawater by PCR using one group-specific oligonucleotide as a primer
    confirm that the oligonucleotide targets only members of this phylogenetic
    cluster.  Likewise, sequences of 16S rDNA obtained from seawater by PCR
    using several different pairs of non-specific primers show an unusually high
    abundance of marine alpha sequences (52 to 84%) among the clones and
    indicate a PCR bias toward the group.  Members of the marine alpha group
    were readily cultured from coastal seawater, accounting for 40% of the
    colonies isolated on low-nutrient marine agar based on hybridizations with
    the group-specific 16S rDNA probe and sequence analysis.  This is the first
    description of a numerically dominant cluster of coastal bacteria,
    identified by molecular techniques, that can be readily cultured and studied
    in the laboratory.