title: A novel non-blue laccase from Bacillus amyloliquefaciens: secretory expression and characterization.
abstract: Laccases are copper-containing enzymes which possess a promising potential in many industrial and environmental applications. Here we describe the cloning, extracellular expression and characterization of a novel non-blue laccase from Bacillus amyloliquefaciens in Pichia pastoris. The recombinant enzyme was secreted into the culture supernatant with high activity. It lacks the absorption band at 610 nm typical for blue laccases. However, electron paramagnetic resonance (EPR) spectrum proved the existence of type 1 copper center that was not detectable in the UV-visible spectrum. Metal content analysis revealed that the enzyme contains two copper ions, one iron ion and one zinc ion per protein molecular, suggesting that it is a novel non-blue laccase. The pH and temperature optima of the recombinant laccase were 6.6 and 60°C, respectively, and it was stable at pH 9.0 for 10 days. The enzyme activity was slightly activated by NaCl with concentration up to 200 mM. The purified laccase showed high efficiency in decolorizing reactive black 5 and indigo carmine, achieving more than 93% decolorization after 1h. The extreme robustness of the recombinant B. amyloliquefaciens laccase offers several advantages over most fungal laccases in various industrial applications.
authors.affiliation: College of Life Sciences, Northeast Forestry University, Harbin 150040, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Chen
authors.affiliation: College of Life Sciences, Northeast Forestry University, Harbin 150040, China.
authors.forename: Wen-Qi
authors.initials: WQ
authors.lastname: Xu
authors.affiliation: College of Life Sciences, Northeast Forestry University, Harbin 150040, China.
authors.forename: Xin-Ru
authors.initials: XR
authors.lastname: Pan
authors.affiliation: College of Life Sciences, Northeast Forestry University, Harbin 150040, China. Electronic address: leilu82@yahoo.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Lu
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D042845:Laccase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008670:Metals / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D008670:Metals; D011994:Recombinant Proteins; D042845:Laccase
keywords: Bacillus amyloliquefaciens; Decolorization; Non-blue laccase