Avaliação da capacidade de solubilização de fosfato por isolados dos gêneros Penicillium e Aspergillus

Abstract

Tropical soils are often deficient in available phosphorus, a major limitation to agricultural productivity. The biological solubilization of insoluble phosphates by soil fungi is a promising strategy to enhance phosphorus availability in agroecosystems. In this context, the present study aimed to select fungal isolates (Aspergillus and Penicillium) with high phosphate-solubilizing capacity. Sixteen isolates were evaluated in Pikovskaya’s (PVK) and NBRIP media containing an insoluble phosphate source. The solubilization index (SI) was calculated, and extracellular acid phosphatase activity was quantified using p-nitrophenyl phosphate (pNPP) as substrate, according to Tabatabai and Bremner (1969). The isolates showed SI values ranging from 0.93 to 1.52, with Aspergillus niger 11799 being the most effective isolate. No direct correlation was observed between SI and phosphatase activity, indicating the involvement of complementary mechanisms in phosphate solubilization. In conclusion, certain isolates, especially Aspergillus niger 11799, are promising for use as microbial agents in phosphorus management of agricultural soils. These phosphate-solubilizing fungi can serve as microbial inoculants capable of mobilizing soil phosphorus, thereby reducing reliance on chemical phosphate fertilizers.