Isolation and characterization of two phosphate-solubilizing fungi from rhizosphere soil of moso bamboo and their functional capacities when exposed to different phosphorus sources and pH environments.

Phosphate-solubilizing fungi (PSF) generally enhance available phosphorus (P) released from soil, which contributes to plants' P requirement, especially in P-limiting regions. In this study, two PSF, TalA-JX04 and AspN-JX16, were isolated from the rhizosphere soil of moso bamboo (Phyllostachys edulis) widely distributed in P-deficient areas in China and identified as Talaromyces aurantiacus and Aspergillus neoniger, respectively. The two PSF were cultured in potato dextrose liquid medium with six types of initial pH values ranging from 6.5 to 1.5 to assess acid resistance. Both PSF were incubated in Pikovskaya's liquid media with different pH values containing five recalcitrant P sources, including Ca3(PO4)2, FePO4, CaHPO4, AlPO4, and C6H6Ca6O24P6, to estimate their P-solubilizing capacity. No significant differences were found in the biomass of both fungi grown in media with different initial pH, indicating that these fungi could grow well under acid stress. The P-solubilizing capacity of TalA-JX04 was highest in medium containing CaHPO4, followed by Ca3(PO4)2, FePO4, C6H6Ca6O24P6, and AlPO4 in six types of initial pH treatments, while the recalcitrant P-solubilizing capacity of AspN-JX16 varied with initial pH. Meanwhile, the P-solubilizing capacity of AspN-JX16 was much higher than TalA-JX04. The pH of fermentation broth was negatively correlated with P-solubilizing capacity (p