Screening of high-efficiency phosphorus-solubilizing bacteria in the rhizosphere of Camellia oleifera and their phosphorus solubilizing characteristics
[Objective]A strain of highly efficient phosphorus-solubilizing bacteria was isolated from the rhizosphere soil of Camellia oleifera,and its phosphorus-solubilization characteristics and effects on the growth of C.oleifera were investigated.[Method]Inorganic phosphorus selection medium was used for the screening of the phosphorus-solubilizing bacteria.The morphological characteristics were observed,and the taxonomic status was determined.The growth curve was determined to identify the optimal growth time of the strain.Functional selection medium was used to determine the strain's ability of nitrogen fixation,potassium solubilization,protease solubilization,cellulase solubilization,amylase solubilization,and iron-producing carriers,as well as to determine the content of its secretion of indole-3-acetic acid(IAA).Antagonistic experiments against the pathogen of Camellia anthracnose were conducted to evaluate its disease resistance.The optimal salt concentration,suitable nitrogen and carbon sources and optimal calcium phosphate addition were determined.The fermented broth of the phosphate-solubilizing bacteria was applied to potted C.oleifera through root irrigation and foliar spraying,and the activities of phenylalanine ammonialyase(PAL),polyphenol oxidase(PPO),peroxidase(POD)in leaves,as well as urease and acid phosphatase activities in the soil and soil content of effective phosphorus,were measured.[Result]The efficient phosphate-solubilizing strain CSUFT-GXP-084 was isolated,with a D/d value of 3.67.The dissolved phosphorus content was 60.35 mg/L.Molecular identification confirmed it as Burkholderia territorii.The strain exhibited nitrogen fixation,protease,and iron carrier production ability,with an IAA secretion content of 4.42 mg/L.It inhibited the growth of five kinds of pathogens causing anthracnose in C.oleifera.Additionally,the salt tolerance range of strain CSUFT-GXP-084 was 0%～5%.The most suitable nitrogen and carbon sources for the phosphorus solubilization ability of the strain CSUFT-GXP-084 were ammonium sulfate,and the optimal amount of calcium phosphate was 2 g/L.Foliar spraying of the CSUFT-GXP-084 bacterial solution had greater effects on the PAL,PPO,and POD activities of the oil tea leaves,while root irrigation had greater effects on urease and acid phosphatase activities in the soil.The effective phosphorus content in the soil increased by 1.58 times and 1.70 times compared with CK after the root irrigation and leaf spraying treatments,respectively.[Conclusion]The strain CSUFT-GXP-084 demonstrates a high phosphorus solubilization ability,enhancing enzyme activity of C.oleifera leaves,soil enzyme activity,and effective phosphorus content in the soil;thus,it holds potential applications in microbial fertilizers and biocontrol agents.
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