Static magnetic field enhances Cladosporium sp. XM01 growth and fungal Mn(II) oxidation.

Fungal Mn oxidation is a crucial pathway in the biogeochemical cycling of toxic substances. However, few studies have aimed to promote the process of fungal Mn oxidation or systematically establish the mechanism of action. The effects of static magnetic field (SMF) treatment on the growth and Mn(II) oxidation capability of an Mn-oxidizing fungus, Cladosporium sp. XM01, were investigated. Results showed that 20.1 mT SMF treatment promoted the growth of strain XM01, and increased the Mn(II) removal rate by accelerating the adsorption and oxidation of Mn(II). In addition, the results of RNA sequencing suggested that SMF mainly stimulated energy metabolism and protein synthesis, accelerating the growth of strain XM01. Notably, KEGG pathway enrichment analysis found that SMF treatment significantly up-regulated the pathway of oxidative phosphorylation system, which is capable of stimulating the generation of superoxide (O). Moreover, exposure to 20.1 mT SMF significantly promoted the activities of antioxidant enzymes including SOD and CAT. These results indicate that SMF treatment stimulates the generation of O by strain XM01, and therefore, accelerates Mn(II) oxidation. This is a novel study using external SMF treatment to enhance fungal Mn(II) oxidation.