Systematic Investigation of Phosphate Decomposition and Soil Fertility Modulation by the Filamentous Fungus <i>Talaromyces nanjingensis</i>

Phosphate-solubilizing microbes (PSMs) in soil play a crucial role in converting insoluble phosphates into plant-available soluble phosphorus. This paper systematically presents a comprehensive array of qualitative and quantitative techniques to assess the phosphate-decomposing capabilities of microbes. Additionally, it introduces two optimized media, namely improved Monkina medium No. 1 and No. 2, which are particularly suitable for detecting the solubilization abilities of microbes toward insoluble organic phosphates. <i>Talaromyces nanjingensis</i>, a novel fungal species recently isolated from the rhizosphere soil of <i>Pinus massoniana</i>, demonstrates remarkable phosphate-solubilizing abilities. Across multiple temperature gradients (15 °C, 20 °C, 25 °C, 30 °C, and 37 °C), it effectively decomposes both insoluble inorganic and organic phosphates. This is achieved through the secretion of organic acids, including gluconic acid (6.10 g L⁻¹), oxalic acid (0.93 g L⁻¹), and malonic acid (0.17 g L⁻¹), as well as phosphate-solubilizing enzymes. Moreover, under low-, medium-, and high-temperature conditions, <i>T. nanjingensis</i> can decompose insoluble phosphates in three types of soil with varying pH levels, thereby enhancing the overall soil fertility. Genomic analysis of <i>T. nanjingensis</i> has identified approximately 308 genes associated with phosphate decomposition and environmental adaptability, validating its superior capabilities and multi-faceted strategies for phosphate mobilization. These findings underscore the wide applicability of <i>T. nanjingensis</i> in maintaining soil phosphorus homeostasis and optimizing the phosphorus use efficiency, highlighting its promising potential for agricultural and environmental applications.