Table 4.

Contributions of the three major bacterial lineages to algal-bloom DNA as determined by various 16S rRNA-based techniques

Sample no.Phylogenetic group% Contribution to algal-bloom DNA based on:
Group-specific probeScreened 16S rDNA clonesSequenced 16S rDNA clonesaT-RFLP analysisb
1 Roseobacter 21.551235
SAR8615.916135.3
SAR1119.0161810.0
Σf 56.4374350.3
11 Roseobacter 27.471448.0
SAR868.718356.0
SAR1132.02422.0
Σ68.1275376.0
60 Roseobacter 30.12110.5
SAR86NDd 005.7
SAR11ND1234c 10.5
Σ143526.7
All samplese Roseobacter 22.5 ± 15.95939.8 ± 12.9
SAR867.0 ± 6.411164.7 ± 2.1
SAR1111.8 ± 11.2101914.4 ± 5.9 
  • a Percent contribution to sequenced clones is adjusted to account for bias toward Roseobactersequences in original selection of the clones and underrepresentation of sequences with multiple mismatches to the group-specific probe.

  • b Based on identification of unambiguous peaks as a percentage of the total area under the chromatogram.

  • c The two chimeric sequences are not included.

  • d ND, not determined.

  • e Group-specific probe data are based on 41 (Roseobacter), 11 (SAR86), or 9 (SAR11) samples; 16S rDNA data are based on 3 samples; and T-RFLP data are based on 17 samples. Values are averaged across stations and depths.

  • f Σ, total bacterial rRNA genes or rDNA amplicons accounted for by the three major lineages.