Influence of oxygen on 4-AAQB biosynthesis of Antrodia cinnamomea during submerged fermentation

• Main Authors: Yu-Ying Wei, 魏瑜瑩
• Other Authors: Been-Huang Chiang
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/6np8d8

碩士 === 國立臺灣大學 === 食品科技研究所 === 106 === Antrodia cinnamomea (AC) is a traditional pharmaceutical fungus native to Taiwan, which is well-known for its diverse bioactivities. A wide variety of bioactive compounds have been isolated from both fruiting body and mycelium of AC. 4-acetylantroquinonol B (4-AAQB) is a kind benzoquinone derivatives isolated from mycelium of AC, showing great inhibition activity on HepG2 cell with only 0.1 ppm of IC50 value. The biosynthetic pathway of 4-AAQB was constructed and found to be highly relevant to another bioactive benzoquinone compound, antroquinonol (AQ), by Chou et al 1. According to the structures of intermediates in the constructed pathway, the conversion of several upstream compounds seems to be relevant to redox reaction. Therefore, this study aims to investigate the influence of oxygen on biosynthetic pathway of 4-AAQB and AQ during submerged fermentation of AC. Addition of oxygen vectors, including 5% of n-hexadecane and n-dodecane, induced approximately 4-folds and 2-folds increase of 4-AAQB respectively in shake flask submerged fermentation. Different oxygen vectors (hydrocarbons) would result in different particle size of mycelium, color of fermentation broth, and the yields of target secondary metabolites. Submerged cultivation of ac in 5 L stirred bioreactor using 5% of n-hexadecane as oxygen vector, the yields of 4-AAQB and AQ in the vector treated group was about 8 –folds and 21-folds higher than the control group. Further analyses of upstream compounds by LC-MS-MS revealed that oxygen vector accelerated farnesylation of benzoquinone ring precursors and reduction of CoQ3B and CoQ3 in the biosynthetic pathway. We suspect that during submerged cultivation of AC, the prenesyltransferase (PTase) and ketoreductase dependent chemical reactions require electrophilic molecular for accepting the release of electrons from ionized cofactors, and the elevated DO concentration by oxygen vector may facilitate these chemical reactions, which in turn increased the yields of AQ and 4-AAQB.