外源因子对桦褐孔菌发酵产桦褐孔菌醇的影响

食药用真菌因其丰富的天然活性物质成为具有开发潜力的药物来源。桦褐孔菌Inonotus obliquus作为一种珍稀的药用真菌,因其对糖尿病、消化系统疾病、心血管疾病、肝病和癌症等疾病有良好的治疗效果而受到广泛关注。桦褐孔菌醇（inotodiol）是桦褐孔菌特有的一种羊毛甾烷型三萜类化合物,具有多种抗癌活性。本文的主要目的是研究外源因子的添加对桦褐孔菌液态发酵产桦褐孔菌醇的影响,以及对桦褐孔菌醇合成途径中酶活的影响。结果表明：最佳外源因子是香叶醇,最佳添加浓度和添加时间分别为0.02%（V/V）和第144小时。发酵结束时（240h）桦褐孔菌醇的产量为27.89mg/L是对照组（9.23mg/L）的3.02倍。通过对比添加香叶醇后桦褐孔菌醇的产量变化以及合成途径中4种酶（法尼基焦磷酸合酶、角鲨烯合酶、角鲨烯环氧化酶和羊毛甾醇合酶）的活性变化,对香叶醇的作用机制进行了初步探究。研究结果表明添加香叶醇后,4种酶活性均较对照组有显著的提高,与此对应的桦褐孔菌醇产量也显著增加,说明这4种酶在桦褐孔菌醇合成途径中起到了积极的作用。

Effects of elicitors on the production of inotodiol by submerged fermentation of Inonotus obliquus

A precious medicinal mushroom Inonotus obliquus has attracted great attention because of its significant therapeutic effect on diabetes, digestive disorders, cardiovascular diseases, liver ailments and cancer etc. Inotodiol is regarded as a characteristic lanostane-type triterpenoid of Inonotus obliquus with various anticancer activities. The effect of addition of elicitors on inotodiol production and enzyme activity in inotodiol synthesis pathway of Inonotus obliquus was investigated. The results showed that the best elicitor tested was geraniol. The appropriate addition concentration was 0.02% (V/V) and suitable point of addition was 144th hour of fermentation. Under the optimal conditions, the product of inotodiol (27.89mg/L) was 3.02 times of that of the experimental control (9.23mg/L) at the end of fermentation (240h). The mechanism of action of geraniol was explored by comparing the changes of inotodiol production and the activity of four enzymes (farnesyl pyrophosphate synthase, squalene synthase, squalene epoxidase and lanosterol synthase) in the biosynthesis pathway. It was indicated that the activities of the four enzymes were significantly higher in comparison with the control group, and the product of inotodiol was correspondingly increased, demonstrating that the four enzymes played a positive role in the biosynthesis pathway of inotodiol.