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

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. 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 dry mycelia and a bioadsorption capacity of 57 mg g. 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 , , and seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater.