title: Properties of the newly isolated extracellular thermo-alkali-stable laccase from thermophilic actinomycetes, Thermobifida fusca and its application in dye intermediates oxidation.
abstract: Laccases are diphenol oxidases that have numerous applications to biotechnological processes. In this study, the laccase was produced from the thermophilic actinomycetes, Thermobifida fusca BCRC 19214. After 36 h of fermentation in a 5-liter fermentor, the culture broth accumulated 4.96 U/ml laccase activity. The laccase was purified 4.64-fold as measured by specific activity from crude culture filtrate by ultrafiltration concentration, Q-Sepharose FF and Sephacryl™ S-200 column chromatography. The overall yield of the purified enzyme was 7.49%. The molecular mass of purified enzyme as estimated by SDS-PAGE and by gel filtration on Sephacryl™ S-200 was found to be 73.3 kDa and 24.7 kDa, respectively, indicating that the laccase from T. fusca BCRC 19214 is a trimer. The internal amino acid sequences of the purified laccase, as determined by LC-MS/MS, had high homology with a superoxide dismutase from T. fusca YX. Approximately 95% of the original activity remained after treatment at 50°C for 3 h. and approximately 75% of the original activity remained after treatment at pH 10.0 for 24 h. This laccase could oxidize dye intermediates, especially 2,6-dimethylphenylalanine and p-aminophenol, to produce coloring. This is the first report on laccase properties from thermophilic actinomycetes. These properties suggest that this newly isolated laccase has potential for specific industrial applications.
authors.affiliation: Department of Cosmetic Science, Providence University, Taichung 43301, Taiwan. chyang@pu.edu.tw.
authors.forename: Cheng-Yu
authors.initials: CY
authors.lastname: Chen
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Huang
authors.forename: Chien-Mei
authors.initials: CM
authors.lastname: Wei
authors.forename: Menghsiao
authors.initials: M
authors.lastname: Meng
authors.forename: Wen-Hsiung
authors.initials: WH
authors.lastname: Liu
authors.forename: Chao-Hsun
authors.initials: CH
authors.lastname: Yang