An improved method for purifying genomic DNA from forest leaf litters and soil suitable for PCR

An improving knowledge of bacterial community within natural environments including forest soils and leaf litters requires extraction of nucleic acids directly from environmental samples since molecular approaches provide less biased access to a larger portion of uncultivable microorganisms. However, when DNA was extracted successfully from these samples, it might still have been difficult to apply it as a template for polymerase chain reaction (PCR) amplifications due to the effect of PCR inhibitors. Various compounds from plant tissues including polysaccharides, phenolic compounds and especially humic acids can inhibit PCR amplification. Some of these inhibitors could inhibit PCR amplification by chelating the Mg2+ (cofactor for Taq polymerase), or by binding to target DNA, and PCR amplification would consequently be interfered with. Therefore, eliminating the effects of these PCR inhibitors is one of the most important steps for PCR-based molecular techniques. Four different methods were assessed in this study to purify the genomic DNA extracted from F, L layer leaf litters and forest soil in an exotic pine plantation of southeast Queensland, Australia