An Improved DNA Extraction Method Using Skim Milk from Soils That Strongly Adsorb DNA

Abstract

DNA extraction has been difficult from some types of soil. Seven soil samples from agricultural fields and a forest, which were mainly volcanic ash soils, were used. Soil DNA could be extracted from only two of them using a commercially available kit exploiting bead-beating. When skim milk was added to the extraction buffer at 40 mg g-1 soil, DNA could be detected by electrophoresis from all the samples, indicating that the DNA from lysed cells was adsorbed by soil colloids. The addition of skim milk did not affect PCR-DGGE profiles. The improved method is applicable to the analysis of molecular communities in soils which strongly adsorb DNA.