Variations in the Extraction and Clean-Up Efficiency of DNA Isolates During Anaerobic Digestion of Wastewater Sludge at Mesophilic and Thermophilic Temperatures

The effect of anaerobic sludge digestion on the isolation of DNA and clean-up efficiency of obtained DNA isolates was studied. Sludge samples were taken from a mesophlic full-scale, and batch digesters operated under mesophilic and thermophilic conditions. Declines over 90% in the extraction yield were observed over time for the batch reactors. The purity of the DNA isolates was assessed by purity ratios: Abs260/280 and Abs260/230. Before the clean-up, the latter declined as a result of digestion in all reactors. DNA mass calculations showed that the mesophilic reactors had the highest recovery (≥ 80%) during the clean-up. The observations of the current investigation strongly indicate that the change in DNA extraction yield was at least partly due to the change of DNA extraction efficiency and not just the change of the actual DNA content. This is an important consideration for the quantification of biomass, specific genes, and microbial populations