Intrinsic enzyme‐like activity of magnetite particles is enhanced by cultivation with Trichoderma guizhouense

Summary Fungal–mineral interactions can produce large amounts of biogenic nano‐size (~ 1–100 nm) minerals, yet their influence on fungal physiology and growth remains largely unexplored. Using Trichoderma guizhouense NJAU4742 and magnetite (Mt) as a model fungus and mineral system, we have shown for the first time that biogenic Mt nanoparticles formed during fungal–mineral cultivation exhibit intrinsic peroxidase‐like activity. Specifically, the average peroxidase‐like activity of Mt nanoparticles after 72 h cultivation was ~ 2.4 times higher than that of the original Mt. Evidence from high resolution X‐ray photoelectron spectroscopy analyses indicated that the unique properties of magnetite nanoparticles largely stemmed from their high proportion of surface non‐lattice oxygen, through occupying surface oxygen‐vacant sites, rather than Fe redox chemistry, which challenges conventional Fenton reaction theories that assume iron to be the sole redox‐active centre. Nanoscale secondary ion mass spectrometry with a resolution down to 50 nm demonstrated that a thin (