Solubilização de fosfato por Aspergillus sp e Penicillium sp em condições de déficit hídrico

Abstract

Phosphorus is essential for plant development, but its low availability in soils compromises agricultural productivity, requiring intensive use of phosphate fertilizers. However, up to 70% of applied phosphorus becomes unavailable to plants, contributing to environmental contamination. Water scarcity further exacerbates this scenario, making the use of drought-tolerant phosphate-solubilizing microorganisms (PSMs) particularly relevant. Thus, this study aimed to evaluate the potential of Aspergillus sp. and Penicillium sp. as phosphate solubilizers under water deficit simulated with PEG. The fungi were maintained in the laboratory through periodic subculturing on Potato-Dextrose-Agar (PDA) at 35°C. Phosphate solubilization capacity was assessed in liquid Pikovskaya medium containing Ca₃(PO₄)₂, AlPO₄, FePO₄, and commercial fertilizers (Termo Fino, Termo Forte, Termo Gran, Tal Qual, and MV27), with and without PEG. Additionally, the production of phytase and acid phosphatase enzymes was evaluated in TLE medium using rice husk, soybean meal, and corn stover as carbon sources at 3, 5, 7, and 10 days. Both fungi solubilized the three inorganic phosphate sources, with values ranging from 12 to 367 µg P/mL. Penicillium sp. showed the highest indices, reaching 367 µg P/mL with AlPO₄ in the presence of PEG. Fertilizer solubilization ranged from 0.27 to 733 µg P/mL, with the highest values recorded for Aspergillus sp. and Penicillium sp. after seven days with PEG, in the fertilizers Termo Forte Simplex and Termofosfato Gran, respectively. Regarding acid phosphatase production, Aspergillus sp. and Penicillium sp. reached 173.5 and 208 U/mL, respectively, using soybean meal on day 5. For phytase, the highest values were 2.230 U/mL for Aspergillus sp. and 1.720 U/mL for Penicillium sp., both with rice husk on day 10. The results highlight the potential of these fungi as promising bioinputs to enhance phosphorus availability under water stress conditions, reducing the dependence on chemical fertilizers.