The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China,
Environ Sci Pollut Res Int. 2015 Jun;22(12):9515-23. doi: 10.1007/s11356-015-4426-6. Epub 2015 Apr 7.
Fungal laccases are typically unstable at high pH and temperature conditions, which limit their application in the decolorization of textile wastewater. By contrast, the highly stable bacterial laccases can function within a wider pH range and at high temperatures, thus have significant potential in treatment for textile wastewater. In our previous work, a thermo-alkali-stable CotA-laccase gene was cloned from Bacillus pumilus W3 and overexpressed in Escherichia coli. In this study, the robust CotA-laccase achieved efficient secretory expression in Bacillus subtilis WB600 by screening a suitable signal peptide. A maximum CotA-laccase yield of 373.1 U/mL was obtained at optimum culture conditions in a 3-L fermentor. Furthermore, the decolorization and detoxification of textile industry effluent by the purified recombinant CotA-laccase in the presence and absence of redox mediators were investigated. Among the potential mediators that enhanced effluent decolorization, acetosyringone (ACS) was the most effective. The toxicity of the CotA-laccase-ACS-treated effluent was greatly reduced compared with that of the crude effluent. To the best of our knowledge, this study is the first to report on the heterologous expression of CotA-laccase in B. subtilis. The recombinant strain B. subtilis WB600-5 has a great potential in the industrial production of this bacterial enzyme, and the CotA-laccase-ACS system is a promising candidate for the biological treatment of industrial textile effluents.
真菌漆酶通常在高 pH 值和温度条件下不稳定，这限制了它们在纺织废水脱色中的应用。相比之下，高度稳定的细菌漆酶可以在更宽的 pH 值范围和高温下发挥作用，因此在处理纺织废水方面具有很大的潜力。在我们之前的工作中，从解淀粉芽孢杆菌 W3 中克隆了一种耐热耐碱的 CotA 漆酶基因，并在大肠杆菌中过表达。在这项研究中，通过筛选合适的信号肽，在枯草芽孢杆菌 WB600 中实现了 CotA 漆酶的高效分泌表达。在 3-L 发酵罐中，在最佳培养条件下，获得了 373.1 U/mL 的最大 CotA 漆酶产量。此外，还研究了纯化的重组 CotA 漆酶在存在和不存在氧化还原介体的情况下对纺织工业废水的脱色和解毒作用。在增强废水脱色的潜在介体中，乙酰丁香酮（ACS）是最有效的。与原废水相比， CotA 漆酶-ACS 处理后的废水的毒性大大降低。据我们所知，这项研究首次报道了 CotA 漆酶在枯草芽孢杆菌中的异源表达。重组枯草芽孢杆菌 WB600-5 菌株在该细菌酶的工业生产中具有很大的潜力，而 CotA 漆酶-ACS 体系是处理工业纺织废水的有前途的候选方案。
