Isolation,optimization And Application Of Taxus Rhizosphere-derived Laccase Strains

Laccase has the potential to be implemented in various industrial fields, such as waste water treatment(transportation and civil engineering), polymer syntheses, discoloration of textile dye, and pulp biobleaching, etc. The liquid medium used for laccase production contained 200 g potato extract with 20 g dextrose, 5g yeast extract, 20 g bran, 3g KH2PO4 and 2g Mg SO4. In this study, we isolated four laccase-producing fungus strains. Based on morphological characteristics and sequence analysis of r DNA-ITS, N is identified as Talaromyces, DX is Aspergillus sp. SL-F20, DC is Alternaria sp. and H is Myrotheium verrucaria. The optimum conditions of laccase production were investigated by single factor experiment and statistically-based uniform design. Sucrose was the optimal carbon source and peptone was the optimal nitrogen source for laccase production. The highest laccase yield was obtained on the fifth day of DC culture, the sixth day of DX and H cultures, and the seventh day of N culture. Guaiacol was used as the substrate in determining laccase activity. Strain H, in single factor optimization, had the highest laccase activity of 216.2 u/m L. Decolorization and degradation of eight reactive dyes, active green 19, reactive black 5, reactive brilliant red, etc., was investigated. It was found that anthraquinone reactive dyes could be directly degraded by the laccase of the studied fungus strains. When the starting concentration of reactive dyes was 20 mg/L, the decolorization percentage was well above 70% after four day treatment. H strain had the best decolorizing effect and the decolorizing efficiency of reactive turquoise blue was more than 95%. fungi with wastewater treatment capacity could be isolated from plant rhizosphere, which, after optimization, have a good application prospect and potential in industrial wastewater treatment, green transportation, environment protection and sustainable development.