Biodegradation of methyl red dye by a novel actinobacterium Zhihengliuella sp. ISTPL4: Kinetic studies, isotherm and biodegradation pathway

Abstract

Among azo dyes, methyl red dye is mutagenic and its persistence causes serious impacts on the environment and human health. The current study is the first report of methyl red dye degradation by an actinobacterium, Zhihengliuella sp. ISTPL4. Strain showed 98.87% of 500 mg/L methyl red dye degradation within 12 h. Optimization of the efficient decolorization by the strain, Quadratic regression model analysis was done by using R software. The kinetic studies revealed the biosorption of dye and explained by Freundlich isotherm model where maximum adsorption was observed (0.99) followed by a pseudo second order reaction. N,N -dimethyl-p-phenylaminediamine (DMPD), and 2-aminobenzoic acid (2-ABA) were detected as key metabolites. Whole genome sequencing analysis showed the presence of azoreductase enzyme. FTIR analysis showed the reductive cleavage of the methyl red azo bond. Furthermore, the degradation pathway of methyl red has been proposed. With these results, we propose a novel application of Zhihengliuella sp. ISTPL4 in methyl red dye degradation at higher concentration.