Fe-P solubilization by Talaromyces helicus (L7B) is influenced by nutrients availability

DELLA MÓNICA, IVANA F.; GODEAS, ALICIA M.; SCERVINO, JOSÉ MARTÍN

Congreso; 7th Symposium on Phosphorus in Soils and Plants; 2022

Phosphorus (P) is an essential nutrient for plant growth and development. It is found as insoluble forms in soils but can be solubilized by soil microbiota. Here, we studied the fungal strain Talaromyces helicus (L7B) as iron phosphate (FeP, 7g/l) solubilizer under different nutritional conditions: 2 concentrations (low:0,1g/l, high:1g/l) of inorganic-N (Ammonium Nitrate:AN and Ammonium Sulphate:AS) and organic-N (Asparagine:A and Tryptophan:T), and 10g/l of Carbon (Glucose:G, Saccharose:S, Fructose:F). LB7 was grown in liquid medium and agitation for 96h and biomass, soluble P, pH, phosphatases, and organic acids (OA) production was measured. Biomass production was highest with F (regardless N) and high-AN (regardless C). Fungal growth was accompanied by pH decrease, particularly with inorganic-N sources. High-N-F lead to high solubilization. High-T-F combination produced the highest solubilization (722,41±118,84 ug P/ml). Organic-N sources (low concentration), regardless C sources, produced low solubilization, while with inorganic-N sources (low) the solubilization rates depended on the N-C combination. The lowest FeP solubilization was present in low-T-G, coinciding with the lowest pH decrease, biomass and phosphatases production. The highest total-OA was produced in high-AS-S (1,8767±0,3791mM) coinciding with high pH decrease; the lowest was produced in high-A-F treatment where scarce pH decrease was found. Formate was the highest-OA produced with inorganic-N with G and S, while with F the major OA produced were gluconate and succinate. Citrate was the highest OA in all organic-N sources treatments, except for A-S (pyruvate) and T-F (acetate). Here we showed that T. helicus can solubilize FeP, and that this solubilization depend directly on nutrients amount and quality. It seems that the two most important mechanisms involved in this process are the OA release (particularly citrate and formate) and pH drop. The better understanding of fungal P solubilization and the nutritional conditions that affect this process could bring a better use of soil resources.