BACKGROUND 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. RESULTS 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. CONCLUSIONS The optimal growth conditions to produce laccase-like active cell-free supernatants from T. asperellum 1 were 1.8 mM CuSO4 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.

中文翻译：

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筛选五种海洋来源的真菌菌株，它们具有产生具有适合生物技术应用的漆酶活性的氧化酶的潜力。

背景技术环境污染是当今世界面临的主要问题之一。已经采取了几种方法，从物理和化学方法到生物技术策略（例如使用氧化还原酶）。来自微生物的氧化酶提供了适合于生物技术应用（例如工业染料脱色）的环保，经济高效的方法。这项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的真菌菌株，以鉴定漆酶样活性，并生产和表征感兴趣的活性无细胞上清液，以进行染料脱色。结果在筛选了从Sfax和Monastir（突尼斯）港口分离出的20种真菌菌株后，鉴定出5种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属于曲霉木霉菌，Stemphylium lucomagnoense和构巢曲霉。在这五种分离物中，一种曲霉（T. asperellum 1）菌株分泌的氧化活性最高，因此被选作进一步研究。首先进行液体培养物生长培养基的优化，以提高培养物上清液中漆酶样活性的水平。最后，在存在或不存在1-羟基苯并三唑（HBT）作为介体的情况下，曲霉1的培养物上清液使属于各种染料家族的不同合成染料脱色。结论从曲霉1产生漆酶样活性无细胞上清液的最佳生长条件是1.8 mM CuSO4作为诱导物，1％NaCl用于模拟海水环境，而3％蔗糖作为碳源。曲霉1的培养上清液有效地使属于不同化学类别的不同合成染料脱色，并且HBT作为介质的存在改善了脱色过程。