title: Improvement of laccase production and its properties by low-energy ion implantation.
abstract: Low-energy ion implantation was employed to breed laccase producing strain Paecilomyces sp. WSH-L07 and a mutant S152 that exhibited an activity of more than three times over the wild strain was obtained. The optimum substrate of both the wild and mutant laccases was 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate), and followed by guaiacol with optimal pH at 3.4 and 5.0, respectively, while the mutant laccase exhibited a broader active pH range. The mutant laccase had a higher optimal catalytic temperature (60-65 degrees C) than the wild one (55 degrees C), and the wild laccase deactivated rapidly when temperature increased above 55 degrees C. Furthermore, the mutant laccase was more stable under neutral and alkaline conditions. A thermostability experiment revealed that the mutant laccase was superior to the wild laccase. Both laccases were stable in the presence of metal ions, mildly inhibited by SDS (0.5 mM), EDTA (1 mM) and 1,4-dithiothreitol (0.5 mM), and almost completely inhibited by 0.1 mM NaN(3).
authors.affiliation: Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Liu
authors.forename: Dongxu
authors.initials: D
authors.lastname: Zhang
authors.forename: Zhaozhe
authors.initials: Z
authors.lastname: Hua
authors.forename: Jianghua
authors.initials: J
authors.lastname: Li
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D042845:Laccase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D020125:Mutation, Missense; D020037:Sordariales / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D005656:Fungal Proteins; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D042845:Laccase