Lactobacillus kefiranofaciens所生產的胞外多醣是一種水溶性的多醣，名為克弗蘭多醣(Kefiran)，因為結構與其他物理、化學性質特殊，將可以廣泛的被應用於食品、醫藥工業方面。 本研究目的在探討不同在pH 值下液態發酵培養對乳酸菌L. kefiranofaciens生產胞外多醣及乳酸之影響，與產生之多醣生物活性的影響。 實驗結果發現控制pH 5.5時，最有利於菌體的生長，不論是單位基 值對菌體轉化率Y(x/s)或比生長速率(μ)都是最高的，分別為104 mg/g及0.063 1/hr；而控制pH 5的時候最有利於胞外多醣的生成，單位基質及單位菌體的多醣產率分別為19.4 mg/g及195 mg/g。而在乳酸轉化率方面，發現低pH值有助於乳酸的產生。 在克弗蘭多醣的生物活性測定上，在不同初始pH之血清瓶實驗中， 發現多醣活性並沒有差異，可能是由於分子量並無明顯差異；而在控不同pH值發酵槽條件下培養，發現於pH 5的多醣其生物活性最高。發現多醣活性隨著分子量成正比的關係，分子量較大，其生物活性也隨之較高。 Exopolysaccharide(EPS) which is produced by Lactobacillus kefiranofaciens is a kind of water-soluble exopolysaccharide, named kefiran. It is widely applied to food and pharmaceutical industry due to its unique structure and physical, chemical properties. The purpose of this study is to discuss the impact of fermentation on L. kefiranofaciens when it produce exopolysaccharide and lactic acid under different pH value. Research has shown that pH 5.5 is the most favorable environment for cell growth, both Y (x / s), which is 104 mg / g, and μ, which is 0.063 1/hr, are the highest. Also, pH 5 is most favorable for the formation of EPS, with Yp/s 19.4 mg/g and Yp/x 195 mg/g and low pH is good for the generation of lactic acid. With EPS biological activity measuring, no difference was found in TNF released between different initial pH in Serum bottle, no significant difference in Molecular Weight might be the reason. And different pH values in the fermenter culture conditions, the EPS found in the pH 5 the highest biological activity. Proportional with the molecular weight polysaccharide found in the relationship between activity, molecular weight, the higher the biological activity also followed.
