Decolorization of heterocycle dye Neutral Red by white-rot fungus Perenniporia subacida

Abstract

A white-rot fungus Perenniporia subacida was developed for decolorizing twelve structurally various dyes from anthraquinone, azo, heterocycle, thiazine, and triphenylmethane groups. Among them, heterocycle dye Neutral Red with preferable decolorization performance was selected for further experiments and this strain could be utilized sequentially for three consecutive cycles with declining decolorization (%). After a 10-day incubation period, higher dye uptake (96.56%) was obtained at constant inoculum and agitation speed with the optimum physicochemical parameters like initial pH at 4.0, temperature at 35°C, initial dye concentration at 100 mg/L, and ionic strength at 0.1 mol/L. Noteworthy induction of various dye decolorizing enzymes viz. lignin peroxidase, laccase, manganese peroxidase, tyrosinase, and nicotinamide-adenine dinucleotide hydrogen-2,6-dichlorophenol indophenol reductase compared to control, point out toward their involvement in overall decolorization and degradation process. Analytical studies like fourier transform infrared spectroscopy and gas chromatography–mass spectroscopy were used to identify the degraded metabolites and scrutinize the degradation process. Phytotoxicity studies indicated that the fungal treatment favors detoxification of dye Neutral Red. It is suggested that P. subacida has great potential for decolorizing heterocycle dyes.

Keywords:

• Perenniporia subacida
• Heterocycle dye
• Dye decolorization
• Reusability
• Metabolites characterization
• Detoxification

Acknowledgments

We express our gratitude to Prof. Yu-Cheng Dai (Beijing Forestry University, China), Prof. Wei-Fa Zheng (Xuzhou Normal University, China), and Dr. Hai-Jiao Li (Beijing Forestry University, China) for improving the manuscript. This study was supported by the Fundamental Research Funds for the Central Universities (Nos. BLYJ201304, JC2013-1) and the Program for New Century Excellent Talents in University (NCET-11-0585).