Effect of a Spent Mushroom Substrate-based fungal-bacterial consortium on the degradation of phenanthrene and pyrene and microbial communities in soils

Purpose: The study aims to cultivate a sustainable fungal-bacterial consortium, utilizing spent mushroom substrate (SMS) as a support, to enhance the degradation of phenanthrene (Phe) and pyrene (Pyr) in contaminated soils, overcoming the limitations and secondary pollution risks associated with conventional physicochemical remediation methods. Methods: The methodology combined SMS characterization, adsorption kinetics, and isotherm analysis to assess the PAH adsorption capacities. A highly efficient microbial consortium was acclimated and applied across various treatment groups, with degradation dynamics monitored using GC-MS. Enzymatic activities and high-throughput sequencing were employed to investigate fungal-bacterial interactions and community dynamics. Results: The study revealed a superior adsorption capacity for Phe over Pyr, with the MBSMS group(Sterilized SMS+PAH-degrading microbial consortium) achieving maximum degradation efficiencies of 94.28% for Phe and 80.67% for Pyr. Fungal extracellular oxidases were found to play a predominant role in PAH degradation, while sterilized SMS enhanced functionality by eliminating bacterial competition. Microbial community restructuring favored Ascomycota and Allorhizobium, shifting bacterial co-occurrence networks from competitive to mutualistic interaction patterns. Functional predictions indicated glutathione transferase upregulation, key in PAH detoxification, particularly in SMS treatments. Furthermore, fungal communities exhibited elevated non-specific monooxygenase activity, further supporting PAH degradation. Conclusion: SMS synergistically enhances PAH adsorption, nutrient provision, and niche optimization, fostering cross-kingdom symbiosis. The complementary roles of fungal enzymatic activation and bacterial mineralization, coupled with the ecological resilience of sterilized SMS, establish a multifunctional bioremediation system. This approach not only achieves high-efficiency PAH removal but also valorizes agricultural waste, providing a scalable and eco-friendly strategy for soil rehabilitation.