New cost-effective mediator enhanced enzymatic degradation of aniline blue

Aim: In this study, the effects of various agricultural wastes as low-cost, readily available alternatives to chemical mediators for the enzymatic degradation of aniline blue were investigated. Methodology: Enzymes for degrading aniline blue were obtained through solid-state fermentation (SSF) of Pleurotus eryngii. Agricultural waste including grape skin/seed and orange peel, rich in organic acids, were used instead of chemical reagents as mediators. The degradation products were subjected to liquid chromatography-mass spectrometry (LC-MS) analysis. Results: The results show that the enzymes manganese peroxidase and versatile peroxidase were associated with aniline blue degradation. The organic acid-rich agricultural waste (grape seed/skin, orange peels) serving as substitutes for chemical reagents as mediators reduced the cost of the mediator by 99.8% at best, and the 2 hr degradation rate of aniline blue was 97.4% and 95.8%, respectively, increased by at least 4.3%. The LC-MS analysis revealed that aniline blue was degraded into smaller compounds with significantly lower toxicity. Interpretation: Overall, the enzyme–organic acid-rich agricultural waste mediator (grape seed/skin) system effectively degraded aniline blue. This cheap and efficient method for aniline blue degradation can serve as an environmentally friendly technology to treat waste with waste. Key words: Agricultural waste, Aniline blue, Enzymatic degradation, Organic acids, Pleurotus eryngii