Chemically induced oxidative stress improved bacterial laccase-mediated degradation and detoxification of the synthetic dyes

• Published in: Ecotoxicology and environmental safety Vol. 226; p. 112823
• Main Authors: Liu, Jiashu, Chen, Jianhui, Zuo, Kangjia, Li, Huanan, Peng, Fang, Ran, Qiuping, Wang, Rui, Jiang, Zhengbing, Song, Huiting
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.12.2021; Elsevier
• Subjects: Bacillus pumilus; Detoxification; Laccase; Oxidative stress; Synthetic dye; Bacillus pumilus; Oxidative stress; Synthetic dye; Detoxification; Laccase
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2021.112823

To alleviate the risk of textile effluent, the development of highly effective bioremediation strategies for synthetic dye removal is needed. Herein, we aimed to assess whether intensified bioactivity of Bacillus pumilus ZB1 by oxidative stress could improve the removal of textile dyes. Methyl methanesulfonate (MMS) induced oxidative stress significantly promoted laccase expression of B. pumilus ZB1. Both the level of hydrogen dioxide and superoxide anion showed a significant positive correlation with laccase activity (RSQ = 0.963 and 0.916, respectively) along with the change of MMS concentration. The regulation of laccase expression was closely related to oxidative stress. The overexpressed laccase in the supernatant improved the decolorization of synthetic dyes (16.43% for Congo Red, 54.05% for Crystal Violet, and 41.61% for Reactive Blue 4). Laccase was subsequently expressed in E. coli. Investigation of the potential of bacterial laccase in dye remediation using Congo Red showed that an effective degradation of azo dye could be achieved with laccase treatment. Laccase remediation alleviated the cytotoxicity of Congo Red to human hepatocytes. In silico study identified eight amino acid residues of laccase involved in binding with Congo Red. Overall, regulation of oxidative stress towards bacterium can be used as a promising approach for the improvement of bacterial bioactivity in synthetic dye remediation. [Display omitted] •Methyl methanesulfonate increased H2O2 and superoxide anion levels in B. pumilus ZB1.•Laccase expression was improved by chemically induced oxidative stress.•The bacterial laccase efficiently decolorized a variety of synthetic dyes.•Laccase treatment could alleviate the cytotoxicity of Congo Red.•Eight amino acid residues in laccase interacted with Congo Red.