Solubilizing effect of Entoloma clypeatum on insoluble phosphorus

Abstract:

[Background] Ectomycorrhizal fungi (ECMF) can promote plants to absorb insoluble phosphorus in the soil. [Objective] To study the mycelial growth and phosphorus solubilization of Entoloma clypeatum with different insoluble phosphorus sources, so as to provide a basis for further research and application of the fungus. [Methods] An ECMF strain was isolated by the tissue culture method and identified based on the internal transcribed spacer (ITS) sequence. The effects of lecithin, aluminum phosphate, calcium phytate, and iron phosphate on the mycelial growth, available phosphorus content, phosphorus solubility, pH, citric acid content, and acid phosphatase content of the strain were determined under pure culture conditions. [Results] The strain was identified as E. clypeatum, and its mycelia grew normally in solid and liquid media with different phosphorus sources. The mycelial growth was slow in the solid media, and the dry weight of mycelial pellets in the liquid medium supplemented with lecithin was the highest. The available phosphorus content (75.029 mg/L) and phosphorus-solubilizing rate (9.31%) of the strain were the highest in the medium containing calcium phytate and the lowest (25.880 mg/L and 0.55%, respectively) in the medium supplemented with lecithin. The pH of each fermentation broth decreased over time. The citric acid content was the highest (19.4 mmol/L) in the medium supplemented with phytic acid calcium and the lowest (12.4 mmol/L) in the medium supplemented with lecithin, which were 1.9-5.1 times that of the control group. The acid phosphatase content in the media supplemented with different insoluble phosphorus sources was 1.3-3.2 times that of the control. It was the highest (0.006 7 U/mL) in the medium with calcium phytate as the insoluble phosphorus source, with significant differences from that in the other three treatments (P<0.05). The available phosphorus content was positively correlated with phosphorus-solubilizing rate (P<0.05) and citric acid content (P<0.01) and negatively correlated with pH and mycelial pellet dry weight. [Conclusion] E. clypeatum capable of solubilizing insoluble phosphorus serves as an excellent choice to reduce the use of phosphate fertilizer. The findings provide a reference for the development and utilization of E. clypeatum and further research on the phosphorus-solubilizing mechanism of ECMF.