Decolorization and detoxification of Brilliant Crocein GR by a newly enriched thermophilic consortium

Fang Tian; Guang Guo; Weilian Fu; Shiji Li; Keqiang Ding; Feng Yang; Chengyue Liang

doi:10.1016/j.jenvman.2024.120623

Decolorization and detoxification of Brilliant Crocein GR by a newly enriched thermophilic consortium

J Environ Manage. 2024 Apr:356:120623. doi: 10.1016/j.jenvman.2024.120623. Epub 2024 Mar 22.

Authors

Fang Tian¹, Guang Guo¹, Weilian Fu², Shiji Li², Keqiang Ding¹, Feng Yang¹, Chengyue Liang³

Affiliations

¹ College of Environmental Engineering, Nanjing Institute of Technology, Nanjing, 211167, China.
² School of Energy and Environmental Science, Yunnan Normal University, Kunming, 650500, China.
³ School of Energy and Environmental Science, Yunnan Normal University, Kunming, 650500, China. Electronic address: liangcy@ynnu.edu.cn.

PMID: 38518494
DOI: 10.1016/j.jenvman.2024.120623

Abstract

The environmental pollution caused by azo dyes at high temperatures has become an urgent problem. However, little attention has been paid to decolorizing azo dyes by thermophilic consortiums. In this study, a thermophilic bacterial consortium (BCGR-T) mainly composed of two genera, namely, Caldibacillus (70.90%) and Aeribacillus (17.63%) was first enriched, which can decolorize Brilliant Crocein GR (BCGR) at high temperatures (50-75 °C), pH values of 6∼8, dye concentrations (100-400 mg/L) and salinities (1-5%, w/v). The enzyme activity results showed that the azoreductase activity was nearly 8.8 times that of the control (p < 0.01), and the intracellular lignin peroxidase was also highly expressed with enzyme activity of 5.64 U (min^-1 mg^-1 protein) (p < 0.05), indicated that both azoreductase and intracellular lignin peroxidase played an important part in the decolorization process. Furthermore, seven new intermediate metabolic products, including aniline, phthalic acid, 2-carboxy benzaldehyde, phenylacetic acid, benzoic acid, toluene, and 4-methyl-hexanoic acid, were identified. In addition, functional genes related with the azo dye decolorization, such as those encoding the azoreductase, laccase, FMN reductase, NADPH-/NADH-quinone oxidoreductases and NADPH-/NADH dehydrogenases, catechol dioxygenase, homogentisate 1,2-dioxygenase, protocatechuate 3,4-dioxygenase, gentisate 1,2-dioxygenase, azobenzene reductase, naphthalene 1,2-dioxygenase, benzoate/toluate 1,2-dioxygenase, and anthranilate 1,2-dioxygenase and so on were found in the metagenome of the consortium BCGR-T. Finally, a new decolorization pathway of the thermophilic consortium BCGR-T was proposed. In addition, the phototoxicity of BCGR decreased after decolorization. Overall, the thermophilic consortium BCGR-T could be a promising candidate in the treatment of high concentration azo dye wastewater at high temperatures.

Keywords: Brilliant Crocein GR; Degradation pathway; Metagenome; Thermophilic consortium.

MeSH terms

Azo Compounds
Biodegradation, Environmental
Coloring Agents
Dioxygenases*
NAD*
NADP
Naphthalenesulfonates*

Substances

brilliant crocein
NAD
NADP
Azo Compounds
Dioxygenases
Coloring Agents
Naphthalenesulfonates