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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/33093

Title: Detoxification of azo dyes by a novel pH-versatile, salt-resistant laccase from Streptomyces ipomoea
Authors: Molina-Guijarro, José M.
Pérez Torres, Juana
Muñoz-Dorado, José
Guillén Carretero, Francisco
Moya Lobo, Raquel
Hernández Cutuli, Manuel
Arias Fernández, María Enriqueta
Issue Date: 2009
Abstract: A newly identified extracellular laccase produced by Streptomyces ipomoea CECT 3341 (SilA) was cloned and overexpressed, and its physicochemical characteristics assessed together with its capability to decolorize and detoxify an azotype dye. Molecular analysis of the deduced sequence revealed that SilA contains a TAT-type signal peptide at the N-terminus and only two cupredoxine domains; this is consistent with reports describing two other Streptomyces laccases but contrasts with most laccases, which contain three cupredoxine domains. The heterologous expression and purification of SilA revealed that the homodimer is the only active form of the enzyme. Its stability at high pH and temperature, together with its resistance to high concentrations of NaCl and to typical laccase inhibitors such as sodium azide confirmed the unique properties of this novel laccase. The range of substrates that SilA is able to oxidize was found to be pH-dependent; at alkaline pH, SilA oxidized a wide range of phenolic compounds, including the syringyl and guayacil moieties derived from lignin. The oxidative potential of this enzyme to use phenolic compounds as natural redox mediators was shown through the coordinated action of SilA and acetosyringone (as mediator), which resulted in the complete detoxification of the azo-type dye Orange II.
Sponsorship: This work was financially supported by the Spanish Ministry of Science (CICYT Project CTQ2004-0344/PPQ to MEA and BFU 2006-00972/BMC to JMD). We thank the Autonomous Government of Madrid and the University of Alcalá for the fellowship awarded to R.M.
Publisher: Sociedad Española de Microbiología
Keywords: Streptomyces ipomoea
Laccases
Azo-dye detoxification
URI: http://hdl.handle.net/10481/33093
ISSN: 1139-6709
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Molina-Guijarro, J.M.; et al. Detoxification of azo dyes by a novel pH-versatile, salt-resistant laccase from Streptomyces ipomoea. International Microbiology, 12: 13-21 (2009). [http://hdl.handle.net/10481/33093]
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