Methyl Red degradation by a subseafloor fungus Schizophyllum commune 15R-5-F01: efficiency, pathway, and product toxicity.

Abstract

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. S. commune 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L^-1 Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. S. commune 15R-5-F01 is capable of achieving repeated cycles of Methyl Red reduction with sustained degradation duration minimum of 6 cycles. It showed a maximum Methyl Red biodegradation capacity of at least 558 mg g^-1 dry mycelia and a bioadsorption capacity of 57 mg g^-1. Gas chromatography-mass spectrometry analysis confirmed the azo reduction of Methyl Red into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Enzymatic activity assays indicated the involvement of lignin peroxidases, laccases, and manganese peroxidase in the biodegradation process. Phytotoxicity tests on Triticum eastivum, Oryza sativa, and Vigna umbellata seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies S. commune 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater.