Mutational screening of fungal strain with high yield of laccase and enzyme production condition of the mutant
漆酶高产菌株的诱变选育及其产酶条件

The basidiospores of Trametes 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 from SAH-12 had increased up to 5002.6 U/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 and tryptone as nitrogen source, the maximum laccase activities were 20544 U/L, 19647 U/L and 16180 U/L, respectively. The initial pH for producing laccase from SAH-12 was 4.0. The ability of producing laccase from SAH-12 was clearly increased by ABTS, tannic acid and gallic acid, among which ABTS and tannic acid were more superior to gallic acid. Laccase production was inhibited by guaiacol and tween 80.