To obtain pure DNA directly from some complex forest soils are still very difficulty at present,though many methods even commercial kits have been attempted.This paper reports an economic and efficient method for further purifying crude DNA extracted from forest soils with two steps.First,the crude DNA was dissolved using the extraction buffer,which removed the debris by chloroform-isoamyl alcohol,and then reprecipitated the DNA by isopropanol;second,the recovered DNA was further purified with silica spin column.Results show that 82-91% of the humic acids was removed by step one.The remaining humic acids could be completely effaced through the second step.The recovered DNA following this protocol was quite pure and ready for sensitive conventional PCR reactions.This is an economic,efficient,and timesaving method.Moreover,crude DNA extracted by other methods can be also further purified with this new way.
