TABLE 4.

DNA yield and qPCR-based enumeration of the amoA gene before and after modification of the extraction methoda

DNA extraction method and sampling depth (m)DNA yield (ng ml−1)Total copy no. (103 ml−1) in:% Recovery in seeded samples
Seeded samplesNonseeded samples
Phenol-chloroform
    101.64 (0.06)150 (6.4)1.05 (0.12)18.4 (0.5)
    900.21 (0.02)313 (0.09)36.3 (1.05)28.9 (3.3)
New method
    102.01 (0.18)664 (72.1)18.2 (2.8)79.4 (6.0)
    900.90 (0.08)690 (14.9)172 (1.58)64.2 (2.0)
  • a Data are calculated by the volume-based method (equation 1) and are means (SEs) for six (10-m samples) or four (90-m samples) replicates.