Dipartimento di Scienze delle Produzioni Agroalimentari e dell'Ambiente, Laboratorio di Patologia Vegetale Molecolare, Università degli Studi di Firenze, Sesto Fiorentino (Firenze), Italy,
Appl Microbiol Biotechnol. 2015 Oct;99(19):8235-45. doi: 10.1007/s00253-015-6648-4. Epub 2015 Jun 11.
Escherichia coli strain DH5α was successfully employed in the decolorization of commercial anthraquinone and azo dyes, belonging to the general classes of acid or basic dyes. The bacteria showed an aptitude to survive at different pH values on any dye solution tested, and a rapid decolorization was obtained under aerobic conditions for the whole collection of dyes. A deep investigation about the mode of action of E. coli was carried out to demonstrate that dye decolorization mainly occurred via three different pathways, specifically bacterial induced precipitation, cell wall adsorption, and metabolism, whose weight was correlated with the chemical nature of the dye. In the case of basic azo dyes, an unexpected fast decolorization was observed after just 2-h postinoculation under aerobic conditions, suggesting that metabolism was the main mechanism involved in basic azo dye degradation, as unequivocally demonstrated by mass spectrometric analysis. The reductive cleavage of the azo group by E. coli on basic azo dyes was also further demonstrated by the inhibition of decolorization occurring when glucose was added to the dye solution. Moreover, no residual toxicity was found in the E. coli-treated basic azo dye solutions by performing Daphnia magna acute toxicity assays. The results of the present study demonstrated that E. coli can be simply exploited for its natural metabolic pathways, without applying any recombinant technology. The high versatility and adaptability of this bacterium could encourage its involvement in industrial bioremediation of textile and leather dyeing wastewaters.
大肠杆菌 DH5α 菌株成功地用于商业蒽醌和偶氮染料的脱色，这些染料属于酸性或碱性染料的一般类别。细菌在测试的任何染料溶液中都显示出在不同 pH 值下生存的能力，并且在有氧条件下整个染料系列都能快速脱色。对大肠杆菌的作用模式进行了深入研究，证明染料脱色主要通过三种不同途径发生，即细菌诱导沉淀、细胞壁吸附和代谢，其权重与染料的化学性质相关。对于碱性偶氮染料，在有氧条件下接种后仅 2 小时就观察到出乎意料的快速脱色，这表明代谢是碱性偶氮染料降解的主要机制，这一点通过质谱分析得到了明确证实。大肠杆菌对碱性偶氮染料的还原裂解也通过向染料溶液中添加葡萄糖时发生的脱色抑制得到了进一步证明。此外，通过进行大型溞急性毒性试验，在大肠杆菌处理的碱性偶氮染料溶液中未发现残留毒性。本研究结果表明，大肠杆菌可以简单地利用其天然代谢途径，而无需应用任何重组技术。该细菌的高通用性和适应性可能鼓励其参与纺织和制革废水的工业生物修复。
