Phosphate solubilization by filamentous fungi from Antarctic lichens and sediments

We aimed to investigate the phosphate solubilization by filamentous fungi isolated from Antarctic lichen and sediment. The results yielded a total of 80 strains, 9 of which were positive for phosphate solubilization in solid NBRIP medium. Cladosporium sp. 1EM.P1 and Penicillium steckii 5Y.P4 showed the largest halos, indicating their potential in phosphate solubilization. Cladosporium sp. 1EM.P1 was the most efficient phosphorus (P) solubilizer with maximum P levels of 106.14 mg/L at 15 °C and 80.89 mg/L at 25 °C. This strain also showed solubilization activity at 0.5 M NaCl with P levels of 127.93 mg/L. At pH 8.0, the P content was 137.93 mg/L, and glucose was the best carbon source (P 146.55 mg/L). Moreover, the isolated fungus showed activity only with tricalcium phosphate as an inorganic phosphate source. During the solubilization process, Cladosporium sp. 1EM.P1 released formic, malic, and succinic acids by the 15th day of incubation (P 208.99 mg/L). These findings indicate that Cladosporium sp. 1EM.P1 from Antarctic sediment has the potential to solubilize phosphate and thus unveils new possibilities for the agricultural sector, aimed to reducing reliance on chemical fertilizers.