[Comparison of direct and indirect environmental DNA extraction methods for samples from a high-temperature...

Two different direct DNA extraction methods and one indirect DNA extraction method were applied to recover environmental DNA from six mat samples, which were sampled closely around a high-temperature spring vent in Tengchong Rehai of the western Yunnan province. As the criteria, quantity and purity of the extracted crude DNA, the result of PCR amplification for denaturing gradient gel electrophoresis (DGGE) before and after crude DNA purification, and the Shannon-wiener index of DGGE profiles were used to evaluate the direct and indirect DNA extraction methods. For the samples of less biomass, the indirect method yielded available crude DNA with high purity, and the DNA was amplified without purification by PCR for DGGE. The two direct methods extracted less DNA than indirect method from the samples of less biomass, and the crude DNA extraction could not be amplified by PCR. Despite the lower quantity of DNA yield, the indirect DNA extraction method for the other' mat samples presented more diverse bacterial community than that of the direct DNA extraction methods according to the Shannon-wiener index of the PCR-DGGE profiles.