Screening of five marine-derived fungal strains for their potential to produce oxidases with laccase activities suitable for biotechnological applications

Abstract

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 CuSO 4 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.

Optimization of the Decolorization of the Reactive Black 5 by a Laccase-like Active Cell-Free Supernatant from Coriolopsis gallica

“…However, the reaction parameters were held at different values, i.e., 75 mg L −1 of Tubantin bath dye, 1 mM HBT, 30 • C, and 20 h [87]. The laccase-active cell-free supernatant of Trichoderma asperellum was also reported to decolorize 90% of 50 mg L −1 RB5 within 24 h in the presence of an HBT mediator [90]. Complete decolorization was achieved on 50 mg L −1 of RB5 within 24 h using purified NADH-dichlorophenol indophenol (NADH-DCIP) reductase and lignin peroxidase (LiP) obtained from Sterigmatomyces halophilus SSA-1575 [91].…”

Isolation and identification of a feather degrading Bacillus tropicus strain Gxun-17 from marine environment and its enzyme characteristics

“…However, these environments are extremely complex and host a broad spectrum of species. Marine microorganisms are clearly a promising source of novel feather-degrading bacteria given their adaption to low temperature, high salinity, high pressure and oligotrophic conditions typical of the marine environment, and their enzymes are potentially very attractive for biotechnology applications owing to their stability and salt tolerance and other properties [ 27 ]. Comparison of biochemical characterisation of B. tropicus Gxun-17 and some microbial keratinase is presented in Table 6 .…”

A New Report on Using a Laccase Producing Yeast for Melanoidin Degradation and Electricity Generation by Microbial Fuel Cell

“…Fungal laccase is found in ascomycetes and basidiomycetes. The yeast produces a true laccase capable of oxidation of phenol and amino-phenol [27]. The ascomycetes yeast Galactomyces sp.…”