Abstract: Phosphate-solubilizing bacteria (PSB) were isolated from 100 soil samples collected from a phosphorous-rich area around the Dianchi Lake of Yunnan Province, Southwest China. The chemotatic PSB strains were screened by cheA gene detection, and their chemotaxis was verified by the method of soft agar plate. The tricalcium phosphate (TCP)solubilizing activities of PSB were determined with molybdenum blue spectrophotometry. Based on 16S rRNA sequences, the phylogenic relationships of the PSB were analyzed. A total of 145 PSB strains with a diameter of phosphatesolubilizing halo zone ranged from 0.5 cm to 2 cm were isolated, among which, 37 strains were chemotactic. The 37 chemotactic strains showed chemotaxis towards four test attractants, and exhibited TCPsolubilizing activity. Phylogenic analysis revealed that the 37 chemotatic strains were belonged to 17 species of 10 genera, in which, Pseudomonas was dominant (9 strains of 5 species), followed by Enterobacter (8 strains of 3 species). Only one species (Bacillus aryabhattai) was isolated from Bacillus, but 9 strains were identified.

Key words: phosphorous-rich area around Dianchi Lake, phosphate-solubilizing bacteria, chemotaxis, phylogenetic diversity.