Abstract: Owing to the complexity of soil physical and chemical properties and the structural particularity of fungal cell wall, the extraction of fungal DNA is more difficult than that of bacterial DNA from soil samples. The soils in North China have their own special properties, compared with the others. Therefore, it is necessary to optimize the extraction method of fungal DNA from soils in North China to study their fungal diversity and composition. Based on the 28S rDNA-PCR-DGGE analysis with fungal universal primers, seven extraction methods were evaluated by adding twelve fungi with greater difference in taxonomy into sterilized black soil. The results showed that two methods were more efficient for the study of soil fungal diversity, i . e ., (1) grinding soil samples in liquid nitrogen, treating them with cellulase, snailase and lysozyme (6, 3, and 1mg·ml^-1, respectively) for 60 minutes at 37 ℃, and lysing with 2% SDS for 30 minutes in 65 ℃ water bath, and (2) freezing and thawing soil samples at -65 ℃ for three times, treating them with cellulase, snailase and lysozyme (6, 3 and 1 mg·ml^-1, respectively) at 37 ℃ for 180 minutes, and lysing with 2% SDS for 30 minutes at 65 ℃. The fungal DNA was extracted from three natural soils with greater differences in physical and chemical properties in North China by using the second method, and the 28S rDNA-PCR-DGGE profiles showed that the fungal DNA bands were comparatively rich, suggesting that this method could be used in fungal diversity research of North China soils.

Key words: Chorthippus dubius, Biology, Spatial pattern, Population dynamics