Biodegradation and detoxification of Direct Black G textile dye by a newly isolated thermophilic microflora

• Published in: Bioresource technology 2018-02, Vol.250, p.650-657
• Main Authors: Chen, Yan, Feng, Linlin, Li, Hanguang, Wang, Yuanxiu, Chen, Guotao, Zhang, Qinghua
• Format: Article
• Language: English
• Subjects: Azo dyes; Decolorization; Degradation pathway; PCR-DGGE; Thermophilic microflora
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2017.11.092

•A newly isolated thermophilic microflora was used to degrade azo dyes.•This thermophilic microflora showed stronger capability for azo dye decolorization.•Biodegradation of azo dyes can be realized under microaerophilic conditions.•The thermophilic microflora converted the toxic dye into low toxicity metabolites.•This study demonstrates the new biodegradation pathway of Direct Black G. The biodegradation and detoxification of azo dye – Direct Black G (DBG) with a newly isolated thermophilic microflora was investigated in the present study. It was found this microflora can decolorize DBG at a wide range of pH from 5 to 10, and grow well under high concentration of dye (600 mg·L−1) and salinity (50 g·L−1). Its decolorization ratio could reach 97% with 8 h of incubation at optimal conditions. The induction of laccase, manganese peroxidase, lignin peroxidase and azoreductase suggests their synergetic involvements in the degradation process of DBG. In addition, the phytotoxicity analysis indicated the thermophilic microflora converted toxic dye DBG into low toxicity metabolites. PCR-DGGE analysis revealed that there are nine different bacteria presented in this microflora. Furthermore, a new degradation pathway of DBG degradation by this microflora was proposed based on the intermediates identified by LC-ESI-MS/MS.