A novel basydiomycete isolated from mangrove swamps in the Colombian Caribbean shows promise in dye bioremediation

Ligninolytic fungi derived from coastal and marine environments, particularly mangrove swamps, are considered potential sources of novel enzymes with unique properties (thermostability, high-redox potential, salt and pH tolerance) not found in terrestrial strains, which are very attractive for the development of effective solutions for the elimination of contamination caused by the textile industry. In this study, the isolation and ligninolytic screening of 73 fungal strains derived from mangrove swamps were achieved. Ten strains showed ligninolytic potential, among which, the basidiomycete identified as INV BAS1 (Cyphellaceae family) exhibited outstanding laccase activity (11873.8 ± 329.0 UL⁻¹). The laccase production was enhanced (5-fold) by optimizing the medium components concentration using a statistical design that combined the one factor at a time method and a central composite rotational design (CCRD), under Response Surface Methodology (RSM). Decolorization of the recalcitrant textile dye Remazol Briliant Blue R (RBBR) was carried out through fermentation and the use of enzyme extracts, reaching decolorization percentages of up to 95.64 ± 1.28 %, under alkaline and high salinity conditions. The laccase activity in the bulk extracts was the major responsible for the RBBR degradation according to gel zymography, UV-Vis and ATR-FTIR spectroscopy. These results contribute to the knowledge of fungal diversity in tropical mangroves and confirm their potential for the development of new bioremediation strategies in high-salt and alkaline effluents generated by the textile industry.