Production of humic substances from cotton stalks biochar by fungal treatment with Ceriporiopsis subvermispora

This study evaluated the biodepolymerization of biochar from cotton stalks gasification using four fungal strains Phanerochaete chrysosporium, Ceriporiopsis subvermispora, Postia placenta, and Bjerkandera adusta. After the biological treatment, the liquid and solid phases were analyzed using UV–Vis and FT-IR spectroscopy. The biochar’s largest depolymerization was obtained by C. subvermispora. The depolymerization kinetic of C. subvermispora showed the production of laccase and manganese peroxidase and a correlation between the depolymerization and the production of ligninolytic enzymes. The highest production of ligninolytic enzymes and depolymerization was observed after 24 days. The modifications in the UV–Vis and FT-IR spectra exhibited the presence of functional groups related with humic substances from cultures with C. subvermispora and cotton stalks biochar.