Whole-cell fungal transformation of precursors into dyes

Abstract

BackgroundChemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes.ResultsAn agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25). Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid) into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water.ConclusionsThis study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other commercially important products. The use of immobilized fungal biomass limits free migration of cells and facilitates their reuse in a continuous system for precursor transformation.

Treatment of Landfill Leachate Using Ganoderma Australe Mycelia Immobilized on Ecomat

“…In this study, the treatment of leachate in column using immobilized G. australe mycelia on Ecomat revealed that BOD 5 was not removed. This may be due to the short exposure of leachate to the immobilized mycelia at the flow-rate used.…”

“…BOD 5 was not removed in diluted leachate nevertheless; in concentrated leachate, 0.43 % and 1.58 % BOD 5 removal occurred at cycle 4 and 10, respectively. However, COD was removed after each cycle and diluted leachate demonstrated higher COD removal ranging from 16.77 -51.62% compared to raw leachate ranging from 1.83 -22.79%.…”

“…Previous study done on pellets (free cell) and immobilized cells of Trametes versicolor showed that removal efficiency of BOD 5 and COD in leachate was found to be higher in the case of immobilized fungi compared to free cell [17]. This is because immobilization of fungal cells could stably maintain the production of various enzymes at levels higher than achieved with pellet form.…”

“…Treatment of leachate was conducted for ten cycles and after two cycles the leachate was analysed for pH, BOD 5 , COD and NH 3 -N. The experimental set-up of Ecomat-immobilized G. australe in column packing is shown in Fig. 1.…”

“…Besides that, the use of Manuscript fungal cultures to transform various chemical compounds has already been reported in several studies [5]. White rot fungi are capable of producing extracellular lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP) that is essential for lignin degradation.…”