Tolerance of three fungal species to heavy metal manganese and the adsorption of the metal

[Objective] To explore the tolerance of three fungal species to manganese ion, the optimal conditions for them to adsorb Mn²⁺ in solution, and the mechanism for the adsorption, and thus to provide technical reference for the control of manganese ion pollution. [Methods] The minimum inhibitory concentration (MIC) of Trichoderma harzianum, T. atroviride and T. asperellum was determined and the optimal adsorption conditions were explored. Based on scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR), fungal cells before and after the adsorption were analyzed. [Results] T. harzianum, T. atroviride, and T. asperellum could tolerate the maximum manganese concentration of 1 600 mg/L, 1 800 mg/L, and 2 000 mg/L, respectively. The optimum adsorption conditions are pH 7, adsorption time of 80 h, and temperature of 28 °C, and the highest adsorption rate was up to 23.7%. The functional groups involved in the adsorption of T. harzianum were −OH, and −C−N− and−C=O in the amine group, and those of T. asperellum were −OH and −NH. The functional groups of T. atroviride were −C−H, and phosphate groups P=O, P−OH, and PO₄³⁻. [Conclusion] The screened T. harzianum, T. atroviride, and T. asperellum showed strong adsorption of heavy metal manganese, which can serve as a reference the treatment of manganese pollution in soil.