Enhanced formation of laccase activity by the white-rot fungus Trametes pubescens in the presence of copper

Abstract

The white-rot fungus Trametes pubescens MB 89 has been identified as an outstanding, although not-yet-described, producer of the industrially important enzyme laccase. Extracellular laccase formation could be greatly stimulated by the addition of Cu(II) to a simple, glucose-based culture medium. Using optimum Cu concentrations (1.5-2.0 mM), maximum values for laccase activity of approximately 65 U/ml were obtained. The synthesis of the laccase protein depended on the presence of Cu in the medium as shown by Western blot analysis. Copper had to be supplemented during the exponential phase of growth for its maximal effect; addition during the stationary phase, during which laccase activity is predominantly formed, resulted in markedly reduced laccase productivity. As was shown by X-ray microanalysis of T pubescens mycelia obtained from a laboratory fermentation, Cu was rapidly taken up by the fungal biomass. A possible explanation for this stimulatory effect of Cu on laccase biosynthesis could be a role for this enzyme activity in melanin synthesis. The stimulatory effect of Cu on laccase synthesis was also effective for several other basidiomycetes and hence could be used as a simple method to boost the production of this enzyme.

Induction and enhancement of the novel marine-derived Alternaria tenuissima KM651985 laccase enzyme using response surface methodology: Application to Azo and Triphenylmethane dyes decolorization

“…Ammonium tartarate, phenol, ABTS and peptone contributed negatively. The positive effect of copper sulphate in our research is in agreement with previous published results ( Galhaup and Haltrich, 2001;Shutova et al, 2008;Zhang et al, 2012). The Cu 2+ is an extremely important metal ion and could induce laccase secretion.…”

Stimulation of laccases from Trametes pubescens: Use in dye decolorization and cotton bleaching

“…In accordance with other reports (15)(16)(17)(18), Cu had a remarkable inducing effect on fungal enzyme synthesis, reaching up to 14 ± 3 U/ml of laccases. In addition to metal ions, aromatic compounds may stimulate laccase production (1), probably due to the presence of recognized stress responsive elements on the gene promoter (6).…”

“…pubescens metabolism is particularly sensitive to several external stimuli (15,16). In this study, copper, veratryl alcohol and two dyes were used to stimulate the laccase production of T. pubescens MUT 2400, which was almost null (20 U/l) in the absence of any appropriate elicitors.…”

Influence of Trace Elements on Ligninolytic Enzyme Activity of Pleurotus ostreatus and P. pulmonarius

“…A stimulatory effect of Zn on laccase activity, noted in P. ostreatus HAI 494, was also demonstrated in Trametes versicolor and T. hirsuta (Collins and Dobson 1997;Keum and Li 2004), while in P. pulmonarius HAI 572 and other tested strains, as well as in T. pubescens this element reduced the activity (Galhaup and Haltrich 2001;Tychanowicz et al 2006), which could be explained by species specificity. Laccase induction could be the result of limited selectivity of the metal-responsive promoter in the laccase gene in P. ostreatus, in which transcription can be controlled by several metal ions, including Zn (Faraco et al 2003).…”

“…Muñoz et al (2006) offers a possible explanation for P. ostreatus, where the stimulatory effect of lower Se concentrations on mycelial growth was demonstrated, contrary to higher concentration. Another interpretation of laccase induction could be the response to the stress caused by excessive amount of Se, namely laccase is involved in the synthesis of pigments which prevent the uptake of trace elements (Galhaup and Haltrich 2001).…”