牛瘤胃分離菌株靜息細胞培養體系生物轉化黃豆苷原

張琪，王秀伶，王世英，郝慶紅，郭云霞，王樹香

河北農業大學生命科學學院，保定 071001

牛瘤胃分離菌株靜息細胞培養體系生物轉化黃豆苷原

張琪，王秀伶，王世英，郝慶紅，郭云霞，王樹香

河北農業大學生命科學學院，保定 071001

從牛瘤胃胃液中分離了一株在厭氧條件下能利用其生長細胞將大豆異黃酮黃豆苷原高效還原為二氫黃豆苷原的革蘭氏陽性細菌菌株 Niu-O16。研究了菌株 Niu-O16靜息細胞體系轉化黃豆苷原的最佳轉化條件，通過單因素試驗確定菌株Niu-O16靜息細胞轉化黃豆苷原的最佳條件是：初始pH 6.0～8.0，靜息細胞濃度32～64 mg/mL(濕重)，加入底物濃度 0.8～1.2 mmol/L。通過正交試驗確定了靜息細胞濃度、加入底物濃度及轉化時間的最佳組合為：靜息細胞濃度32 mg/mL、加入底物濃度0.8 mmol/L、轉化時間24 h；最佳轉化條件下底物轉化率最高為63.9%。該結果為厭氧菌的靜息細胞轉化及工業應用提供了參考。

牛瘤胃細菌，靜息細胞體系，黃豆苷原，二氫黃豆苷原，生物轉化

Abstract:In previous study we isolated a gram-positive bacterial strain, designated Niu-O16, from bovine rumen gastric juice.The growing cells of bacterial strain Niu-O16 is capable of biotransforming isoflavone daidzein into dihydrodaidzein efficiently under anaerobic conditions.In this study we investigated the optimal bioconversion conditions for the resting cells of bacterial strain Niu-O16 to convert daidzein into dihydrodaidzein.Single factor test showed that the optimal conditions for the initial pH of phosphate buffer, the concentration of the resting cell and the concentration of the substrate daidzein were 6.0–8.0, 32–64 mg/mL(wet weight)and 0.8–1.2 mmol/L, respectively.Orthogonal experiments were used to determine the optimal combination of the resting cell concentration, substrate concentration and biotransformation time.The results showed that the optimal combination included resting cell concentration 32 mg/mL, substrate concentration 0.8 mmol/L and the biotransformation time 24 h.Furthermore,the biotransformation kinetics under optimal conditions were studied, under which conditions the highest bioconversion rate was 63.9% in the resting cell system.The results might provide information for resting cell biotransforming of anaerobes as well as its industrial application.

Keywords:bovine rumen bacteria, resting cell system, daidzein, dihydrodaidzein, biotransformation

大豆異黃酮(Soy isoflavones)是大豆在其生長 過程中形成的一類次級代謝產物，主要分布于大豆種子的子葉和胚軸中，其中含量最高的是黃豆苷(Daidzin)和染料木苷(Genistin)。體內及體外試驗均表明，攝入動物體內的大豆異黃酮糖苷，在腸道和肝組織中的β-葡萄糖苷酶作用下首先脫去糖苷，被水解為黃豆苷原(Daidzein)和染料木黃酮(Genistein)。其后，在胃腸道微生物菌群作用下又進一步被降解為各種不同的大豆異黃酮代謝產物。其中黃豆苷原可被降解為二氫黃豆苷原(Dihydrodaidzein，簡稱DHD)、四氫黃豆苷原(Tetrahydrodaidzein，簡稱 THD)、去氧甲基安哥拉紫檀素(O-Desmethylangolensin，簡稱O-Dma)和雌馬酚(Equol)[1-4]等不同代謝產物。……