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 probe	Screened 16S rDNA clones	Sequenced 16S rDNA clonesa	T-RFLP analysisb
1	Roseobacter	21.5	5	12	35
	SAR86	15.9	16	13	5.3
	SAR11	19.0	16	18	10.0
	Σf	56.4	37	43	50.3
11	Roseobacter	27.4	7	14	48.0
	SAR86	8.7	18	35	6.0
	SAR11	32.0	2	4	22.0
	Σ	68.1	27	53	76.0
60	Roseobacter	30.1	2	1	10.5
	SAR86	NDd	0	0	5.7
	SAR11	ND	12	34c	10.5
	Σ		14	35	26.7
All samplese	Roseobacter	22.5 ± 15.9	5	9	39.8 ± 12.9
	SAR86	7.0 ± 6.4	11	16	4.7 ± 2.1
	SAR11	11.8 ± 11.2	10	19	14.4 ± 5.9

^aPercent contribution to sequenced clones is adjusted to account for bias toward Roseobacter sequences in original selection of the clones and underrepresentation of sequences with multiple mismatches to the group-specific probe. 

^bBased on identification of unambiguous peaks as a percentage of the total area under the chromatogram. 

^cThe two chimeric sequences are not included. 

^dND, not determined. 

^eGroup-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. 

^fΣ, total bacterial rRNA genes or rDNA amplicons accounted for by the three major lineages.