Biochemical and molecular characterization of Coriolopsis rigida laccases involved in transformation of the solid waste from olive oil production

DÍAZ, R.; MARIO CARLOS NAZARENO SAPARRAT; JURADO, M.; GARCÍA-ROMERA, I.; OCAMPO, J. A.; MARTÍNEZ, M. J.

APPLIED MICROBIOLOGY AND BIOTECHNOLOGY

SPRINGER

Año: 2010 vol. 88 p. 133 - 142

0175-7598

Two laccase isoenzymes were purified andcharacterized from the basidiomycete Coriolopsis rigidaduring transformation of the water-soluble fraction of“alpeorujo” (WSFA), a solid residue derived from the oliveoil production containing high levels of toxic compounds.Zymogram assays of laccases secreted by the fungusgrowing on WSFA and WSFA supplemented with glucoseshowed two bands with isoelectric points of 3.3 and 3.4.The kinetic studies of the two purified isoenzymes showedsimilar affinity on 2,6-dimethoxyphenol and 2,2´-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid), used as phenolicand non-phenolic model substrate, respectively. The molecularmass of both proteins was 66 kDa with 9% N-linkedcarbohydrate. Physico-chemical properties of the purifiedlaccases from media containing WSFA were similar tothose obtained from medium with glucose as the maincarbon source. In-vitro studies performed with the purifiedlaccases revealed a 42% phenol reduction of WSFA, as wellas changes in the molecular mass distribution. Thesefindings indicate that these laccases are involved in theprocess of transformation, via polymerization by theoxidation of phenolic compounds present in WSFA. Asingle laccase gene, containing an open reading frame of1,488 bp, was obtained in PCR amplifications performedwith cDNA extracted from mycelia grown on WSFA. Theproduct of the gene shares 90% identity (95% similarity)with a laccase from Trametes trogii and 89% identity (95%similarity) with a laccase from Coriolopsis gallica. This isthe first report on purification and molecular characterizationof laccases directly involved in the transformation ofolive oil residues.