Isolation, purification and characterization of the PCBs-degrading enzyme from Xylaria regalis

• Main Authors: Chei-Yi Lin, 林哲毅
• Other Authors: Shenq-Chyi Chang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/42011443048380257145

碩士 === 國立陽明大學 === 生物化學研究所 === 92 === PCBs (Polychlorinated Biphenyls) are widespread pollutants. Many studies have proven that PCBs are hazardous to humans and other animals. Xylaria regalis is a wood-grown saprophytic fungus. Based on previous study, Xylaria regalis is capable of PCBs degradation, and the fungus could degrade more PCBs in SDB medium than in other media. So, We cultured Xylaria regalis in SDB medium and further purified the PCBs-degrading enzyme. We found that culture medium from 10-day growth mycelia could degrade 67 % of Aroclor 1254 (PCBs). And the PCBs-degrading enzyme was further purified by anion exchanger column (QAE Sephadex A-25) and hydrophobic interaction column (Phenyl-650M). The purity of the PCBs-degrading enzyme was increased to 11.60 fold, the specific activity of the PCBs-degrading enzyme was reached to 8.90 x 10-2 unit/mg, and the recovery of the purified enzyme was 108.29 %. The molecular weight of the PCBs-degrading enzyme was found to be approximately 22.5 kDa by HPLC gel filtration and SDS-PAGE. The optimal pH of the enzyme was 7 and the optimal temperature of the enzyme was 30 ℃. The pH stability of the enzyme was 7 and the thermostability of the enzyme was 30 ℃. The iron ions that we studied in different concentration can inhibit the enzyme activity. When EDTA was added in the enzyme solution, the enzyme activity was inhibited.