探討pH值對Agaricus blazei 液態發酵生產一次及二次代謝產物之影響

The influence of pH on production of first and secondary metabolites formation by Agaricus blazei in submerged culture

黃崇凱(Chung-Kai Huang)

指導教授 ： 徐敬衡

國立中央大學/工學院/化學工程與材料工程學系/碩士(2007年)

摘要

Agaricus blazei原產於巴西，為一種食藥用菇，近年來被廣泛地做研究，包括其代謝產物的生物活性等。

隨著A. blazei的療效及生物活性一一被探討出來，快速且大量的提升發酵的產量以及產率也隨之來的重要，隨著各產物的特性不同，各產物的生產條件也不同，本研究為了增加A. blazei液態培養之一次代謝產物粗多醣、麥角固醇和二次代謝產物Blazeispirol A的產量以及探討各產物間的相互關係，藉由改變環境因子pH值來探討，分別討論搖瓶實驗之不同起始培養基pH值為4、5、6、7及發酵槽實驗之控制發酵全程培養基pH值為4、5、6、7四組實驗，在搖瓶及發酵槽實驗中可以得到一致的趨勢，發酵槽實驗中結果發現隨著pH值的提高對粗多醣的產量有著隨之增加的趨勢，從pH值為4時的0.42g/L到pH值=6時有最大的粗多醣產量為0.53g/L；而在pH值為7時粗多醣產量又降為0.41g/L。對麥角固醇而言，則是隨著pH值下降而產量隨之增加。在pH值為7時，麥角固醇的產量為29.45mg/L，隨著pH值下降到pH值為4時有最大產量為43mg/L。但對於二次代謝產物Blazeispirol A而言，卻是隨著pH值的上升而有上升的趨勢，
在pH值為4時有最低產量為0.61mg/L，隨著pH值上升到7時達到了最大產量16.80mg/L，這意味著雖然在低pH值下有利於生產麥角固醇但卻不利於轉換成其它衍生物，如Blazeispirol A。

另外也探討發酵過程全程控制pH值為7以及只控發酵的起始pH值為7之試驗，研究發現在全程控制與不控發酵過程pH值的試驗中，胞外多醣產量分別為0.41以及0.31g/L;而麥角固醇產量則為29.45以及28.33mg/L;至於Blazeispirol A則是為16.80以及12.69mg/L，此外在發酵過程pH值控制為7時發酵所需時間為9天，而只控發酵起始pH值則需為12天，綜合上述無論在產量及產率而言皆是以全程控制發酵過程pH為7之試驗結果較佳，故發酵過程控制pH值是有其必要性的。

利用本研究可以了解培養基的pH值對於A. blazei液態發酵生產多醣、麥角固醇、Blazeispirol A等產物之影響，以提供日後大量生產所需要的產物時之參考。

關鍵字

巴西洋菇 ； 發酵 ； 代謝產物

並列摘要

Higher fungi are abundant sources of a wide range of useful natural products and new products with interesting biological activities . Agaricusl blazei Murill has been traditionally used as a health food source in Brazil for the prevention of cancer, diabetes, hyperlipidaemia, arteriosclerosis and chronic hepatitis.

The effects of the controlled and uncontrolled pH conditions, as well as of the value of initial pH=7 and controlled pH=7, on production of the valuable bioactive metabolites by A. blazei were investigated in a stirred tank fermenter. The experimental result shows, controlled pH operation was more favourable than the uncontrolled pH operations.

The effects of controlled culture pH ranging from pH 4.0 to 7.0 on cell growth, exopolysaccharide biosynthesis, relationship between ergosterol, and blazeispirol A biosynthesis of A. blazei were examined both in shake flask culture and in a stirred tank fermenter. While the set point of the culture pH during fermentation was controlled from 4.0 to 7.0, the specific growth rate (μ) increased monotonically, and the cell production rate had the same trend; Higher the pH control from 4.0 to 6.0 gradually led to a higher production of production of Polysaccharides. At lower the pH control (pH = 4) was optimum for ergosterol production; however, At higher the pH control (pH = 7) was optimum for blazeispirol A generation.

The work is useful for further optimization of this fungal fermentation process highly efficient production of the valuable bioactive metabolites on a bioreactor scale.

並列關鍵字

pH ； Agaricus blazei ； secondary metabolite

參考文獻

劉景仁，2006，“探討誘發劑及兩階段培養對樟芝深層發酵三萜類及抗癌作用之影響”，國立臺灣大學食品科技研究所，碩士論文。

蔡漢霓，2005，“巴西蘑菇萃取物抗氧活性之研究”，國立成功大學醫學檢驗生物技術研究所，碩士論文。

Arinaga S., Karimine N., Takamuku K., Nanbara S., Nagamatsu M., Ueo H., Akiyoshi T. (1992) Enhanced production of interleukin-1 and tumor necrosis factor by peripherai monocytes after lentinan administration in patients with gastric carcinoma. Int. J. Immunopharmac. 14:43-47.

Akiyama T., Shibuya N., Hrmova M., Fincher G. B. (1997) Purification and characterization of a β-(1-3)-D-glucan endohydrolase from rice (Oryza sativa) bran. Carbohy. Res. 297:365-374.

Ashida H., Hashimoto T., Nonaka Y., Minato K. I., Kawakami S., Mizuno M., Fukuda I., Kanazawa K. (2002) Suppressive effect of polysaccharides from the edible and medicinal mushrooms, Lentinus edodes and Agaricus blazei, on the expression of cytochrome P450s in mice. Biosci. Biotechnol. Biochem. 66:1610-1614.