TABLE 2

Percentages of isotopic labeling of DNA with 15N or 13C, calculated from qPCR data of SIP fractions

DomainSeasonSubstrate% incorporationa
BacteriaSummer15NH431
15NO3−4
[15N]urea−2
ArchaeaSummer15NH431
15NO3−5
[15N]urea2
BacteriaWinter15NH49
15NO36
[15N]urea30
ArchaeaWinter15NH423
15NO317
[15N]urea35
BacteriaWinter[13C]bicarbonate17
ArchaeaWinter[13C]bicarbonate18
  • a Percentages in boldface are above the 30% and 15% thresholds used as indicators that uptake of 15N- and 13C-labeled substrates had occurred, respectively.