An enzymatic approach has shown great potential in many environmental and industrial fields of application; in particular, laccases represent good candidates thanks to their versatility and low selectivity of target substrates. Despite the fact they are able to degrade many xenobiotics, their industrial application is highly limited by the enzyme availability at high concentration and reduced costs. According to this, the first goal of this study was to optimize the laccase production by a Trametes pubescens strain: the role of copper, veratryl alcohol, two model dyes and nitrogen was evaluated. In order to assess the maximal potential of stimulation by selected compounds, a central composite design was carried out. High laccase concentration, up to 300 U/ml, was secreted in 500 ml Erlenmeyer flasks; the fermentation conditions in a 10 l reactor, in terms of aeration and agitation, should be still optimized in order to reach the same final yield. A biochemical and catalytical characterization provides useful information for the exploitation of these enzymes in biotechnological processes, which could display extreme pH and temperature working conditions. In detail, the crude extracts maintained 100% of their activity even after 1 hour of incubation at 60°C, showing a half-life at 50°C of two weeks. They resulted very stable in a wide pH range (from 6 to 9) for more than one month. Further studies are in progress in order to evaluate the effectiveness of these enzymes in organic pollutants removal, including dyes, endocrine disrupting chemicals, pharmaceutical compounds, etc. Preliminary data showed that laccases from T. pubescens are able to degrade up to 90% of two model dyes (Acid Blue 62 and Reactive Blue 19) at a concentration of up to 500 ppm. These data showed promising potentials for further biotechnological applications of these enzymes, for example in textile and municipal wastewater treatment, textile finishing, etc.
Spina, Federica ; Nair, Rakesh ; Demarche, Philippe ; Agathos, Spiros N. ; et. al. Laccase production optimization by Trametes pubescens strain: Characterization and application of the crude extract.Oxizymes 2012 (Marseille, France, du 16/09/2012 au 19/09/2012).