Abstract:

Archaea have been discovered in non-extreme environments recently but not in Chinese pristine soils so far. This study was conducted to assess the presence of Archaea in two Asian pristine soils from Xinjiang and Guangxi of China and in two North American soils from southern Arizona region of the United States. Four 16S rDNA clone libraries were generated and 16S rDNAs related to 28 Crenarchaeota were identified in all four soils. All of the 16S rDNA sequences grouped closely with non-thermophilic terrestrial Crenarchaeotae, which is distinct from marine and freshwater crenarchaeotal clusters. Phylogenetic analysis indicated that the recovered 28 crenarchaeotal 16S rDNA sequences belong to two distinct clades that can be distinguished on the basis of either 16S rDNA sequence or G+C content. Our results demonstrate the presence of non-thermophilic Crenarchaeota in two Chinese and two American pristine soils for the first time in these regions, indicating that the range of these organisms is not restricted to extreme conditions. In addition, Clade 2 contains clones only from the American soils, indicating that the geographic locations and soil char-acteristics may influence the types of terrestrial crenarchaeotal populations.