Optimisation of the Production and Bleaching Process for a New Laccase from Madurella mycetomatis , Expressed in Pichia pastoris : from Secretion to Yielding Prominent

Laccases are polyphenol oxidoreductases used in a number of industrial applications. Due to the increasing demand for these “green catalysis” enzymes, the identification and biochemical characterisation of their novel properties is essential. In our study, cloned Madurella mycetomatis laccase ( mmlac ) genes were heterologously expressed in the methylotrophic yeast host Pichia pastoris. The high yield of the active recombinant protein in P. pastoris demonstrates the efficiency of a reliably constructed plasmid to express the laccase gene. The optimal biochemical conditions for the successfully expressed Mm Lac enzyme were identified. Detailed structural properties of the recombinant laccase were determined, and its utility in decolourisation and textile bleaching applications was examined. Mm Lac demonstrates good activity in an acidic pH range (4.0–6.0); is stable in the presence of cationic metals, organic solvents and under high temperatures (50–60 °C); and is stable for long-term storage at − 20 °C and − 80 °C for up to eight weeks. The structural analysis revealed that the catalytic residues are partially similar to other laccases. Mm Lac resulted in an increase in whiteness, whilst demonstrating high efficiency and stability and requiring the input of fewer chemicals. The performance of this enzyme makes it worthy of investigation for use in textile biotechnology applications, as well as within environmental and food technologies.