Faculty of Science, Universidad Nacional de Colombia, Sede Medellín, 050034, Medellín, Colombia.
Biorefining Conversions and Fermentation Laboratory, Department of Agricultural, Food and Nutritional Science, University of Alberta, T6G 2P5, Edmonton, AB, Canada.
J Environ Manage. 2021 May 1;285:112117. doi: 10.1016/j.jenvman.2021.112117. Epub 2021 Feb 18.
Synthetic dye bioremediation is a topic of great importance since these pollutants possess toxic effects, and huge quantities of them are being discharged into water bodies. Ligninolytic enzyme treatment stands out for being a cost-effective methodology, capable of obtaining high decolorization levels. In this work, a laccase enzyme treatment was evaluated to effectively perform a cycle of dye bioremediation. Furthermore, a dye decolorization improvement was also assessed through laccase immobilization. Particularly, a Trametes pubescens enzyme extract was concentrated, immobilized onto calcium alginate beads, and characterized to assess its dye decolorization potential. Ammonium sulfate precipitation and vacuum evaporation were evaluated to concentrate the crude extract and to decolorize allura red AC. Both treatments reached a high enzyme yield recovery (>90%), but only the vacuum-evaporated extract achieved a high allura red AC decolorization level after 16 h of contact time. This suggested that essential compounds for allura red AC decolorization were present in the crude extract, implying that neither a complete laccase purification process nor an addition of synthetic mediators are necessary. Under optimized immobilization conditions, 94.6% immobilization efficiency and 49.8% activity recovery were obtained with 0:1 alginate:enzyme (v/v), 100 mM CaCl, and 5.0% w/v sodium alginate. Furthermore, by immobilizing the laccase concentrated extract, both the pH and temperature stabilities were improved. The decolorization of allura red AC by free and immobilized laccase was 68.4% and 4.6%, respectively, showing that although the enzyme stability was improved, dye decolorization was negatively affected. Thus, an efficient allura red AC decolorization was obtained with concentrated-free laccase by a feasible and low-cost methodology.
合成染料生物修复是一个非常重要的课题，因为这些污染物具有毒性，而且大量的污染物被排放到水体中。木质素酶处理因其具有成本效益，能够获得较高的脱色水平而脱颖而出。在这项工作中，评估了漆酶处理以有效地进行染料生物修复循环。此外，还通过漆酶固定化评估了染料脱色的改进。具体而言，浓缩了绒毛栓菌酶提取物，将其固定在海藻酸钠珠上，并对其染料脱色能力进行了表征。评估了硫酸铵沉淀和真空蒸发来浓缩粗提取物并使诱惑红 AC 脱色。这两种处理方法都达到了很高的酶产回收率（>90%），但只有真空蒸发提取物在 16 小时的接触时间后达到了很高的诱惑红 AC 脱色水平。这表明粗提取物中存在用于诱惑红 AC 脱色的基本化合物，这意味着既不需要完全纯化漆酶，也不需要添加合成介体。在优化的固定化条件下，以 0:1 的海藻酸钠：酶（v/v）、100 mM CaCl2 和 5.0% w/v 海藻酸钠获得了 94.6%的固定化效率和 49.8%的酶活回收率。此外，通过固定化浓缩的漆酶提取物，提高了 pH 和温度稳定性。游离漆酶和固定化漆酶对诱惑红 AC 的脱色率分别为 68.4%和 4.6%，表明尽管酶稳定性得到了提高，但染料脱色受到了负面影响。因此，通过可行且低成本的方法，使用浓缩的游离漆酶可有效地对诱惑红 AC 进行脱色。
