title: Purification and biochemical characterization of a new alkali-stable laccase from Trametes sp. isolated in Tunisia: role of the enzyme in olive mill waste water treatment.
abstract: A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K m and V max values of 0.05 mM and 212.73 μmoL min(-1) mg(-1), respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe(2+), Zn(2+), Cd(2+) and Mn(2+), while Cu(2+) acted as inducer. EDTA (10 mM) and NaN3 (10 mM) were found to completely inhibit its activity. 73 % OMW was dephenolized after 315 min incubation at 30 °C with 2 U mL(-1) of laccase and 2 mM HBT.
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, Ecole Nationale d'Ingénieurs de Sfax, University of Sfax, Route de Soukra Km 4,5, BP 1173, 3038, Sfax, Tunisia.
authors.forename: Dalel
authors.initials: D
authors.lastname: Daâssi
authors.forename: Héla
authors.initials: H
authors.lastname: Zouari-Mechichi
authors.forename: Alicia
authors.initials: A
authors.lastname: Prieto
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Martínez
authors.forename: Moncef
authors.initials: M
authors.lastname: Nasri
authors.forename: Tahar
authors.initials: T
authors.lastname: Mechichi
mesh_terms: D001487:Basidiomycota / Q000145:classification; D001673:Biodegradation, Environmental; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D042845:Laccase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D031658:Olea / Q000378:metabolism*; D059808:Polyphenols / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D055454:Trametes / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D014416:Tunisia; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification; D014934:Wood / Q000382:microbiology
chemical_list: D005656:Fungal Proteins; D042845:Laccase; D059808:Polyphenols; D062065:Wastewater