title: Molecular cloning and heterologous expression of a laccase gene from Pleurotus eryngii in free and immobilized Saccharomyces cerevisiae cells.
abstract: A full length cDNA encoding an extracellular laccase was isolated by reverse transcription polymerase chain reaction from the mycelia of the mushroom Pleurotus eryngii. The isolated sequence, denoted Ery3, encodes for a mature laccase isoenzyme of 531 amino acid residues with a predicted molecular weight of 56.6 kDa. All sequence motifs, being the signature sequences used to identify the laccases, were found in the Ery3 protein sequence. The Ery3 cDNA was expressed in Saccharomyces cerevisiae and the effects of copper concentration and cultivation temperature were investigated. S. cerevisiae cells were immobilized in calcium alginate gel and the optimal immobilization parameters for the enhanced production of laccase were determined. The immobilization was most effective with 3% sodium alginate, 0.1 M calcium chloride and an initial biomass of 4.5 x 10(8) cells. The enzyme yield obtained with immobilized cells (139 mU ml(-1)) showed a 1.6-fold increase compared to the highest yield obtained with free cells. The alginate beads showed good stability and retained 84% capacity of enzyme production after seven repeated cycles of batch fermentation. The immobilization system proved to increase the proteolytic stability of the recombinant Ery3 protein. To our knowledge, this is the first report on S. cerevisiae whole-cell immobilization for recombinant laccase production.
authors.affiliation: Istituto di Scienze delle Produzioni Alimentari del CNR, Unità di Lecce, via Prov le Lecce-Monteroni, Lecce, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Bleve
authors.forename: Chiara
authors.initials: C
authors.lastname: Lezzi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mita
authors.forename: Patrizia
authors.initials: P
authors.lastname: Rampino
authors.forename: Carla
authors.initials: C
authors.lastname: Perrotta
authors.forename: Luciano
authors.initials: L
authors.lastname: Villanova
authors.forename: Francesco
authors.initials: F
authors.lastname: Grieco
mesh_terms: D018533:Biomass; D018914:Cells, Immobilized / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D042845:Laccase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020076:Pleurotus / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D011994:Recombinant Proteins; D042845:Laccase