Ecole Nationale d'Ingénieurs de Sfax, Laboratoire de Biochimie et de Génie enzymatique des lipases, Université de Sfax, Sfax, Tunisie.
Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, INRA UMR1163, Marseille, France.
BMC Biotechnol. 2020 May 12;20(1):27. doi: 10.1186/s12896-020-00617-y.
Environmental pollution is one of the major problems that the world is facing today. Several approaches have been taken, from physical and chemical methods to biotechnological strategies (e.g. the use of oxidoreductases). Oxidative enzymes from microorganisms offer eco-friendly, cost-effective processes amenable to biotechnological applications, such as in industrial dye decolorization. The aim of this study was to screen marine-derived fungal strains isolated from three coastal areas in Tunisia to identify laccase-like activities, and to produce and characterize active cell-free supernatants of interest for dye decolorization.
Following the screening of 20 fungal strains isolated from the harbors of Sfax and Monastir (Tunisia), five strains were identified that displayed laccase-like activities. Molecular-based taxonomic approaches identified these strains as belonging to the species Trichoderma asperellum, Stemphylium lucomagnoense and Aspergillus nidulans. Among these five isolates, one T. asperellum strain (T. asperellum 1) gave the highest level of secreted oxidative activities, and so was chosen for further studies. Optimization of the growth medium for liquid cultures was first undertaken to improve the level of laccase-like activity in culture supernatants. Finally, the culture supernatant of T. asperellum 1 decolorized different synthetic dyes belonging to diverse dye families, in the presence or absence of 1-hydroxybenzotriazole (HBT) as a mediator.
The optimal growth conditions to produce laccase-like active cell-free supernatants from T. asperellum 1 were 1.8 mM CuSO as an inducer, 1% NaCl to mimic a seawater environment and 3% sucrose as a carbon source. The culture supernatant of T. asperellum 1 effectively decolorized different synthetic dyes belonging to diverse chemical classes, and the presence of HBT as a mediator improved the decolorization process.
环境污染是当今世界面临的主要问题之一。人们已经采取了多种方法，包括物理和化学方法以及生物技术策略（例如使用氧化还原酶）。微生物来源的氧化酶提供了环保、经济高效的过程，适用于生物技术应用，例如工业染料脱色。本研究的目的是筛选从突尼斯三个沿海地区分离的海洋来源真菌菌株，以鉴定漆酶样活性，并生产和表征对染料脱色有活性的无细胞上清液。
对来自斯法克斯和莫纳斯提尔（突尼斯）港口的 20 株真菌菌株进行筛选后，鉴定出 5 株具有漆酶样活性的菌株。基于分子的分类学方法将这些菌株鉴定为 Aspergillus nidulans、Stemphylium lucomagnoense 和 Trichoderma asperellum 种。在这五个分离株中，一株 T. asperellum 菌株（T. asperellum 1）表现出最高水平的分泌氧化活性，因此被选择用于进一步研究。首先对液体培养的培养基进行了优化，以提高培养上清液中漆酶样活性的水平。最后，T. asperellum 1 的培养上清液在存在或不存在 1-羟基苯并三唑（HBT）作为介体的情况下，可使不同的合成染料（属于不同染料家族）脱色。
生产 T. asperellum 1 漆酶样活性无细胞上清液的最佳生长条件为 1.8 mM CuSO 作为诱导剂、1% NaCl 模拟海水环境和 3%蔗糖作为碳源。T. asperellum 1 的培养上清液有效地使不同的合成染料（属于不同的化学类别）脱色，而 HBT 作为介体的存在则改善了脱色过程。
