Evaluation of Soil DNA from Arable Land in Japan Using a Modified Direct-extraction Method

Using a widely used commercial DNA extraction kit and a newly modified direct DNA extraction method proposed in this report, soil DNA was extracted from arable land in diverse geological locations in Japan and the quality and quantity of the DNA were examined. A modified direct DNA extraction method was developed, consisting of one-step extraction and two-step purification using potassium acetate and a DEAE-cellulose column, respectively, and designated as a DSPD (Differential Salt Precipitation and DEAE-cellulose) method. The total time needed to process six soil samples with this method was less than two hours, including the time taken to set up the DEAE-cellulose columns. Other advantages of our DSPD method are the use of non-hazardous reagents and running costs only 5-10% of the commercial kits currently used in soil microbiological research. This DSPD method was tested using 24 soil samples collected from diverse locations in Japan and showed that it is a reliable technique for DNA extraction from a wide range of soil types when compared with commercial DNA extraction kits. This DSPD method will therefore contribute to the molecular and genomic analyses of microbial populations and ecosystems that require numerous samples of soil DNA.