Qualitative and quantitative evaluation of the impact of G2-Enhancer on DNA extraction from deep-soil samples

Soil DNA extraction is often challenged by many factors that can affect both yield and pureness of the recovered DNA. Clay particles lead to lower DNA extraction efficiency and further PCR inhibitors can negatively affect downstream analyses when applying DNA sequencing. These effects are even more important when related with a lower biomass samples, as usually observed at deeper soil layers in comparison with the topsoil. Most studies elude these complications using an indirect DNA extraction, with prior isolation of the cells from the matrix; however, such method introduces relevant biases, influencing the microbial community composition. To overcome these issues, we applied a direct DNA extraction method combined with the use of the commercial product G2 DNA/RNA Enhancer, a highly mutagenized fish -sperm DNA, to improve the yield of DNA recovered from clay-rich and DNA limited soils . Specifically the samples used in this study came from soil layers between 1.00 to 2.20 m below ground level. Furthermore, our results show that at a sequence diversity level, no bias seems to be attributable to the application of G2. This can open opportunities to gather a better understanding in topics of increasing interest such as vertical microbial characterization along soil profiles and environmental DNA recovery in samples of low biomass.