Screening Of Inductive-mutant Strain With High Yield Of Laccase, And The Purification, Characterization And Gene Cloning Of The Enzyme From The Mutant

Laccase (EC 1.10.3.2) is one of Cu-contained polyphenol oxidases produced in fungi, especially white rot fungi, and is also found in higher plants, bacteria and insects. Many different roles of laccase have been ascribed. Laccases can react to various substrate such as polyphenol and aromatic diamines. Laccases have provided with great applied foreground and potential value, such as lignin degradation, biobleaching in pulps, environments protect, biosensors, enzymatic synthesis, processing of foodstuffs and beverages. Using Trametes gallica of lignin degradation white rot fungi as initial experimental material, A mutant SAH-12 with high yield of laccase was obtained by ultra-violet ray treatment, and the purification, characterization and gene cloning of its enzyme were investigated. The main results are desribed as following.1. The basidiospores of T. gallica were exposed under ultra-violet ray and the mutants were screened in RBBR-containing PDA plates, and then the laccase activities of the mutated strains were determined by ABTS. A mutant SAH-12 with high yield of laccase was obtained. The maximum activity of laccase of SAH-12 had increased up to 5002.6U/L, and its ability of producing laccase was stable on culture condition of inorganic salt with high nitrogen and low carbon (LM3). Study of laccase production in the liquid culture of SAH-12 showed that cellobiose and sucrose as carbon source were obviously superior to wheat bran, starch and glucose, and the highest laccase activities were 18526 U/L and 13436 U/L, respectively. Organic compound as carbon source was more suitable for the laccase secretion from SAH-12 than inorganic compound. Using peptone, soybean meal...