TABLE 5.

16S rRNA gene copy numbers for the groups of methanogens quantified by RT-PCR in the fresh and mature sludges

Target16S rRNA gene copy no. (copies g−1 sludge) ina:
Fresh sludgeMature sludge
Methanoculleus3.9 × 108 (1.2 × 108)9.0 × 108 (2.2 × 108)*
Uncultured group5.7 × 106 (1.3 × 106)*2.3 × 106 (4.3 × 105)
Methanothermobacter1.6 × 106 (6.0 × 105)1.4 × 106 (7.4 × 105)
MethanosaetaNDND
MethanosarcinaNDND
  • a Standard deviations are given in parentheses (n = 5). Asterisks indicate significant differences at P < 0.05, after Student's t test with SPSS 15.0. ND, not detected (<600 gene copies g−1 sludge).