C–N coupling of 3-methylcatechol with primary amines using native and recombinant laccases from Trametes versicolor and Pycnoporus cinnabarinus

Characterization of recombinant laccase from Trametes versicolor synthesized by Arxula adeninivorans and its application in the degradation of pharmaceuticals

Recent years have seen an increasing interest in laccase enzymes. Due to their ability of oxidizing various substrates, they are nowadays applied in multiple industrial fields including pulp delignification, textile dye bleaching, and bioremediation. In contrast to laccase production from native sources, with its generally low yield and high cost, heterologous laccase expression is far better suited to meet the growing industrial demands. TVLCC5 gene encoding Trametes versicolor laccase 5 was overexpressed in Arxula adeninivorans using the strong constitutive TEF1 promoter. Recombinant Tvlcc5 protein was purified by immobilized-metal ion affinity chromatography and biochemically characterized using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as substrate for standard activity assays. The enzyme showed the highest activity at 50 °C between pH 4.5–5.5. The half-life of Tvlcc5 at 60 °C was around 20 min. The negative effect of chloride anions on enzyme activity was demonstrated. A fed-batch cultivation of Tvlcc5 producing strain A. adeninivorans G1212/YRC102-TEF1-TVLCC5-6H was performed and resulted in a laccase activity of 4986.3 U L⁻¹. To improve the expression level of recombinant laccase in A. adeninivorans, cultivation conditions were optimized by single factor experiments. Recombinant Tvlcc5 proved to be a promising agent for degradation of pharmaceuticals that are an important source of environmental pollution. Concentration of diclofenac and sulfamethoxazole decreased to 46.8% and 51.1% respectively after 24 h incubation with Tvlcc5. When 1 mM redox mediator ABTS was added complete degradation was obtained within 1 h.

Biotransformation and reduction of estrogenicity of bisphenol A by the biphenyl-degrading Cupriavidus basilensis

The biphenyl-degrading Gram-negative bacterium Cupriavidus basilensis (formerly Ralstonia sp.) SBUG 290 uses various aromatic compounds as carbon and energy sources and has a high capacity to transform bisphenol A (BPA), which is a hormonally active substance structurally related to biphenyl. Biphenyl-grown cells initially hydroxylated BPA and converted it to four additional products by using three different transformation pathways: (a) formation of multiple hydroxylated BPA, (b) ring fission, and (c) transamination followed by acetylation or dimerization. Products of the ring fission pathway were non-toxic and all five products exhibited a significantly reduced estrogenic activity compared to BPA. Cell cultivation with phenol and especially in nutrient broth (NB) resulted in a reduced biotransformation rate and lower product quantities, and NB-grown cells did not produce all five products in detectable amounts. Thus, the question arose whether enzymes of the biphenyl degradation pathway are involved in the transformation of BPA and was addressed by proteomic analyses.

Laccase-catalyzed green synthesis and cytotoxic activity of novel pyrimidobenzothiazoles and catechol thioethers

Laccase-catalyzed green reaction between catechols and 2-thioxopyrimidin-4-ones delivers novel pyrimidobenzothiazoles and catechol thioethers with antiproliferative activities against HepG2 cell line.

How to enjoy laccases

An analysis of the scientific literature published in the last 10 years reveals a constant growth of laccase applicative research in several industrial fields followed by the publication of a great number of patents. The Green Chemistry journal devoted the cover of its September 2014 issue to a laccase as greener alternative for chemical oxidation. This indicates that laccase "never-ending story" has found a new promising trend within the constant search for efficient (bio)catalysts able to meet the 12 green chemistry principles. A survey of ancient and cutting-edge uses of laccase in different industrial sectors is offered in this review with the aim both to underline their potential and to provide inspiration for new ones. Applications in textile and food fields have been deeply described, as well as examples concerning polymer synthesis and laccase-catalysed grafting. Recent applications in pharmaceutical and cosmetic industry have also been reviewed.