Abstract: In this study, four core samples were collected from the DK-6 bore holes of gas hydrate-rich deposit districts in the permafrost zone of Qilian Mountains, Qinghai Province of Northwest China, with the total bacterial genome in the samples analyzed. Four 16S rDNA gene libraries were created by PCR. There were 44 OTUs, including five categories, i.e., Firmicutes, Bacteroidetes, Proteobacteria (α-, β-, and γ-Proteobacteria), Actinobacteria, and Deinococcus-Thermus, in the four gene libraries. The microbial communities of different lithology showed a relatively large composition difference, and had different dominant species. Lithology played a certain decisive role to the growth of bacteria. Bore holes DK6-12 (117.5 m) and DK6-17 (161.9 m) were of mudstone, in which, Alcaligenes xylosoxidans was the dominant bacterium. K6-23 (194.6 m) was of fine sandstone, in which, a large number of Spirosoma panaciterrae was found in cloning sequences. DK6-25 (213 m) was of coal, with the highest abundance of Pantoea ananatis. Most of the microbes presented in the four samples could metabolize organic hydrocarbon. Our results indicated that in the gas hydrate-rich deposit districts in permafrost zone, environmental factors limited the diversity of microbes.

Key words: Exotic weeds, Invasion, Species interaction, Allelopathy, Chemical mechanism