Isolation and whole genome sequencing analysis of phosphatesolubilizing bacteria from Jingdezhen Kaolin

【Objective】To isolate phosphate-solubilizing bacteria from Jingdezhen Kaolin and conducted whole genome sequencing analysis， in order to provide a research basis for the exploration of phosphorus-solubilizing microorganisms and their phosphorus-solubilizing characteristics and mechanisms. 【Method】Phosphate solubilizing bacteria were isolated from Jingdezhen Kaolin， and the ability of the strains to decompose inorganic and organic phosphorus were initially evaluated using soluble phosphorus index. The phosphorus solubilization ability of the strains was quantitatively analyzed using Mo-Sb colorimetric method and the alkaline phosphatase activity of the strains were measured using alkaline phosphatase （AKP/ALP） reagent kit. The strains were identified using 16S rDNA， and the strains with the strongest phosphorus solubilization ability were selected for whole genome sequencing， and their phosphorus solubilization-related genes were analyzed. 【Result】Five strains of phosphate-solubilizing bacteria， named GP1， GP2， GP3， GP4 and GP5， were isolated from Jingdezhen Kaolin， which could dissolve both organic and inorganic phosphorus. All five strains could produce alkaline phosphatase. Among them， GP1 had the strongest ability to dissolve inorganic phosphorus and its fermentation broth contained the highest content of soluble phosphorus （61.77 mg/L）. GP4 had the strongest ability to decompose organic phosphorus， with the highest content of soluble phosphorus in its fermentation broth （30.22 mg/L）. The sequencing results of 16S rDNA showed that GP1 and GP3 belonged to the genus Burkholderia sp.， GP2 belonged to the genus Paraburkholderia sp.， and GP4 and GP5 belonged to the Luteiobacter sp. The results of the housekeeping gene identification indicated that GP1 was Burkholderia pyrrocinia. The results of gene annotation showed that strain GP1 contained eight inorganic phosphorus solubilization related genes （pqqA， pqqB， pqqC， pqqD， pqqE， gdh， gltA， ppa）， four organic phosphorus solubilization genes （phoA， phnA， phnW， phnY）， eight phosphorus compound transport genes （ugpB， ugpA， ugpE， ugpC， pstB， pstA， pstC， pstS）， and two phosphorus deficiency responsive dual component regulatory genes （phoR， phoB）. 【Conclusion】Phosphate-solubilizing bacteria exist in Jingdezhen Kaolin， and the isolated bacteria from it have good ability to decompose organic and inorganic phosphorus.， which is a good potential resource for the development of microbial fertilizer. The mechanism by which GP1 solubilizes Ca₃ （PO₄）₂ may be by secretion gluconic acid， citric acid， and inorganic pyrophosphatase. The mechanism by which GP1 decomposes organic phosphorus may be through the secretion of alkaline phosphatase and C-P bond lyases. GP1 also has the potential to adapt to low phosphorus environments.