TABLE 4

Percentages of isotopic labeling of OTUs in winter samplesa with [15N]urea or [13C]bicarbonate

DomainDivision/classFamily/genus% labelingb with:
15N13C
BacteriaProteobacteriaUnclassified3518
AlphaproteobacteriaSAR11 (Surface 1)3014
ArchaeaCrenarchaeotaMarine group I2727
BacteriaGammaproteobacteriaOceanospirillales3912
AlphaproteobacteriaSAR11 (Surface 2)3122
VerrucomicrobiaVerrucomicrobiaceae133
AlphaproteobacteriaRhodobacteraceae1915
GammaproteobacteriaAlteromonadaceae2817
DeltaproteobacteriaSAR324 (marine group B)4913
AlphaproteobacteriaSAR11 (Chesapeake Delaware Bay)3217
VerrucomicrobiaVerrucomicrobiaceae136
DeltaproteobacteriaNitrospinaceae169
AlphaproteobacteriaRhodobacteraceae137
BacteroidetesCryomorphaceae42−9
AlphaproteobacteriaSAR11 (Surface 4)3216
AlphaproteobacteriaSAR11 (Deep 1)3714
AlphaproteobacteriaRhodospirillaceae2920
ActinobacteriaAcidimicrobiales (SVA0996)325
  • a Only OTUs that accounted for more than 0.5% of reads across libraries from gradient fractions are shown. OTUs are shown in rank order, with the first being the most abundant.

  • b Percentages were calculated from 16S rRNA gene OTU frequencies in Illumina libraries with respect to densities of fractions. Percentages in boldface are at or above the 30% and 15% thresholds used as indicators that uptake of 15N- and 13C-labeled substrates occurred, respectively.