Cloning and characterization of FMN-dependent azoreductases from textile industry effluent identified through metagenomic sequencing

Azo dyes, when released untreated in the environment, cause detrimental effects on flora and fauna. Azoreductases are enzymes capable of cleaving commercially used azo dyes, sometimes in less toxic by-products which can be further degraded via synergistic microbial cometabolism. In this study, azoreductases encoded by <i>FMN1</i> and <i>FMN2</i> genes were screened from metagenome shotgun sequences generated from the samples of textile dye industries’ effluents, cloned, expressed, and evaluated for their azo dye decolorization efficacy. At pH 7 and 45°C temperature, both recombinant enzymes FMN1 and FMN2 were able to decolorize methyl red at 20 and 100 ppm concentrations, respectively. FMN2 was found to be more efficient in decolorization/degradation of methyl red than FMN1. This study offers valuable insights into the possible application of azoreductases to reduce the environmental damage caused by azo dyes, with the hope of contributing to sustainable and eco-friendly practices for the environment management. This enzymatic approach offers a promising solution for the bioremediation of textile industrial effluents. However, the study acknowledges the need for further process optimization to enhance the efficacy of these enzymes in large-scale applications. <i>Implications</i>: The study underscores the environmental hazards associated with untreated release of azo dyes into the environment and emphasizes the potential of azoreductases, specifically those encoded by <i>FMN1</i> and <i>FMN2</i> genes, to mitigate the detrimental effects. The study emphasizes the ongoing commitment to refining and advancing the enzymatic approach for the bioremediation of azo dye-containing effluents, marking a positive stride toward more sustainable industrial practices.

偶氮染料（Azo dyes）未经处理直接排放至环境中时，会对动植物群落造成有害影响。偶氮还原酶（Azoreductases）是一类可裂解商用偶氮染料的酶，其部分降解产物毒性更低，可通过协同微生物共代谢途径进一步降解。本研究从纺织印染行业废水样品的宏基因组鸟枪法测序（metagenome shotgun sequencing）序列中，筛选得到由FMN1和FMN2基因编码的偶氮还原酶，并对其进行克隆、表达，同时评估其偶氮染料脱色效能。在pH 7、45℃的条件下，重组酶FMN1与FMN2分别可对浓度为20ppm与100ppm的甲基红实现脱色。实验结果表明，FMN2对甲基红的脱色/降解效率优于FMN1。本研究为利用偶氮还原酶降低偶氮染料造成的环境破坏提供了重要理论参考，有望为环境治理的可持续、生态友好型实践贡献力量。该酶法为纺织工业废水的生物修复（bioremediation）提供了极具潜力的解决方案。不过，本研究同时指出，仍需进一步优化工艺以提升这些酶在大规模应用中的效能。研究启示（Implications）：本研究凸显了未经处理的偶氮染料直接排放至环境所带来的环境危害，并强调了由FMN1、FMN2基因编码的偶氮还原酶在缓解此类有害影响方面的潜力。本研究强调需持续优化并改进该酶法，以实现含偶氮染料废水的生物修复，这为迈向更可持续的工业实践迈出了积极的一步。