Isolation and evaluation of two phosphate-dissolving fungi

Abstract:

[Objective] To isolate phosphate-solubilizing strains from crop rhizosphere soil for functional composite microbial community and bio-fertilizer production.[Methods] The phosphate-solubilizing capacity was evaluated by the halo zone of dissolving phosphate and molybdenum antimony colorimetric. Phosphate-solubilizing fungi were identified based on their morphological and cultural characteristics and β-tubulin sequence analysis. Acid producing substances of phosphate solubilizing fungus were analyzed by GC-MS and the biological compatibility of microbial strains was tested by medium method.[Results] Two phosphate-solubilizing fungi were screened from soybean rhizosphere soil, P1-1, P2-2, which were identified as Aspergillus niger and A. tubingensis. The volatile acids (oxalic acid, gluconic acid, lactic acid and glycerol acid) were detected in both fungi. They were compatible with a group of nematicidal microorganisms (Purpureocillium lilacinum + Streptomyces olivaceus + Ochrobactrum pseudogrignonense). The D/d (diameter of the halo zone/diameter of the colony) value of P1-1 and P2-2 was detected after culturing on three media with Ca₃(PO₄)₂, Zn₃(PO₄)₂ and phosphorite at 25℃ for 5 days, and the available phosphorus contents were detected after 5 days culturing in liquid medium containing Ca₃(PO₄)₂, Zn₃(PO₄)₂ and phosphorite. The results indicated that the two phosphate-dissolving fungi had similar capability in dissolving phosphorus.[Conclusion] Two high-efficient phosphate solubilize fungi were obtained, and they could activate a variety of insoluble phosphorus sources accompanied by the production of volatile acidic substances. The two strains showed good biological compatibility with a group of nematicidal microorganisms.