Characterization of periodic inoculation with Talaromyces affecting the bioavailability of rhizosphere lead in soil-Houttuynia cordata.

Periodic inoculation of the phosphate solubilizing fungus Talaromyces enhanced soil lead (Pb) immobilization and the growth of Houttuynia cordata. Four treatments were established: a control treatment, a single inoculation treatment, a treatment inoculated every 10 days, and a treatment inoculated every 20 days. The results demonstrated that, Talaromyces inoculation decreased soil pH and increased available phosphorus (AP) content by 15.4-24.4 mg/kg via the solubilization of insoluble-P, with periodic inoculation further enhancing phosphorus release. Additionally, periodic inoculation further promoted Pb biomineralization, reducing diethylene triamine pentaacetic acid (DTPA)-extractable lead by 22.7-35.8 mg/kg. This process significantly alleviated Pb toxicity in H. cordata, increasing biomass by up to 44.7 %, and reducing Pb accumulation in roots and shoots by 35.08 mg/kg and 15.37 mg/kg, respectively. Following periodic inoculation, Talaromyces became the dominant fungus. Functional bacteria such as Proteobacteria and Sphingomonas were enriched, and the complexity of the co-occurrence network significantly increased. Redundancy analysis identified AP, Urease activity, and DTPA-extractable Pb as core drivers of microbial community variation. This study demonstrates that periodic fungal inoculation optimizes the rhizosphere micro-ecosystem, enabling simultaneous remediation of heavy metal pollution and enhanced agricultural productivity.