Antrodia cinnamomea, a unique medicinal fungus, has been used as a functional food in Taiwan. Ergosterol is one of the major bioactive compounds isolated from A. cinnamomea, and it has been reported to have anti-tumor and anti-inflammatory activities. However, the influences of the growth medium ingredients on ergosterol biosynthesis in A. cinnamomea remain unknown. In this work, the growth medium was optimized by response surface methodology (RSM) to enhance the ergosterol biosynthesis from the fermentation of A. cinnamomea BCRC 35396. Compared with the control, the optimization by RSM resulted in a 3-fold increase (reaching 12.66 ± 0.37 mg/g dry cell weight) in the ergosterol production with the optimum growth medium (2.5% malt extract, 4.1% glucose, 0.8% peptone, 0.5% soybean powder, and 0.1% MgSO_4．7H_2O). The ergosterol production is positively, linearly related to the glucose level in the medium, but negatively related to the peptone level. From the proteomic comparison by 2-dimensional gel electrophoresis MALDI-TOF/TOF-MS and MS/MS, the co-upregulation of phosphoglycerate mutase and pyruvate dehydrogenase complex E1-α subunit together with increased expression of squalene synthetase was seen when the optimum medium was used. The results indicated that the optimum medium induced a switching of the metabolic flux of acetyl-CoA into the TCA cycle branch and enhanced the ergosterol biosynthesis in the A. cinnamomea culture.
牛樟芝（Antrodia cinnamomea）是台灣特有的藥用真菌，在台灣已被當成保健食品使用。麥角固醇（ergosterol）是從牛樟芝中分離出的主要生物活性化合物之一，根據研究上其具有抗腫瘤和抗發炎的作用。但是，固態培養基中的成分對麥角固醇生物合成的影響仍然未知。因此本篇研究，以反應曲面法（response surface methodology）探討牛樟芝生長培養基成分之優質化，以提高牛樟芝（BCRC 35396）發酵過程中的麥角固醇的生合成。與對照組相比，利用反應曲面法對優質化生長培養基（麥芽萃取物2.5%，葡萄糖4.1%，蛋白腖0.8%，大豆粉0.5%和MgSO_4．7H_2O 0.1%）進行的處理後，麥角固醇的生合成量提高3倍（12.66 ± 0.37 mg/g dry cell weight），而且菌體麥角固醇的生合成量與培養基中葡萄糖含量呈現線性正相關，但是與培養基蛋白腖的含量成負相關性。經由二維凝膠電泳MALDI-TOF/TOF-MS和MS/MS蛋白質體學分析比較後，發現使用優質化之培養基，其磷酸甘油酸變位酶（phosphoglycerate mutase）和複合物E1-α亞基之丙酮酸脫氫酶（pyruvate dehydrogenase complex E1-α subunit）呈現共同向上調控之表現，同時其角鯊烯合成酶（squalene synthetase）的表現量也增加。此結果顯示，反應曲面法優質化之培養基，其誘導菌體生物合成乙醯輔酶A的代謝路徑量提高並進入TCA循環代謝分支，進而提高牛樟芝菌體麥角固醇的生物合成量。
