Abstract

Direct extraction of DNA from soils is a useful way to gain genetic information on the soil source. However, DNA extraction from soils, especially forest soils, may be contaminated by humic substances due to their similar physical and chemical characteristics to soil. Even commercial soil DNA extraction kits fail to retrieve DNA from these soils. Using the potential changes of specific charge of DNA and humic substances in a pH solution, we performed two electrophoreses in different pH buffers to eliminate the interfering substances. The method produced high quality soil DNA, which is applicable for PCR amplification.

Key words: DNA extraction, forest soil, humic substances, pH, specific charge, two-step electrophoreses.