The Composition and Phosphate-Solubilizing Capability of Phosphate-Solubilizing Bacteria in the Rhizosphere of Wild Camellia oleifera in Mountain Lushan

Camellia oleifera, a unique edible oil tree species in China, is of important economic value. However, the shortage of phosphorus in the soil is one of the important factors limiting the growth of C. oleifera. Here, we investigated the population size and composition of culturable phosphate-solubilizing bacteria (PSB) in the rhizosphere soil of wild C. oleifera in Mountain Lushan, China. PSB were isolated using a dilution coating plate method and identified by 16S rRNA sequencing. The phosphate-solubilizing capability of the isolated PSB was evaluated by a semi-quantitative method (the ratio of phosphate solubilization halo diameter versus colony diameter). The results showed that large amounts of PSB existed in the rhizosphere soil of wild C. oleifera (0.28–1.08×107 CFU/g soil) and the population size of PSB differed from investigated trees. A total of 100 strains of PSB were isolated from the rhizosphere soil, belonging to Bacillus, Burkholderia, Pantoea, Paraburkholderia, and Pseudomonas, respectively. Of these strains, Burkholderia showed the highest isolation frequency and phosphate-solubilizing capability, accounting for 61% of the isolates. The phosphate solubilization index of 100 strains varied from 1.02 to 3.04 after a 6-day incubation, and Bacillus strains were easy to lose their phosphate-solubilizing capability during the incubation. Our result suggested that Burkholderia was the dominant genus of PSB in the rhizosphere of C. oleifera and could be utilized for facilitating the uptake of P.