以納豆菌生產木聚醣酶

Abstract

由本實驗室所篩選出具有產生最高活性之木聚醣酶之Bacillus subtilis natto #14，其發酵上清液酵素最適活性條件為pH 5、50℃。利用合成培養基之銨鹽化合物及少量酵母萃取物作為氮源，並比較葡萄糖、蔗糖、木糖、甘油對其生長之影響，以葡萄糖作為最適培養碳源。使用多種誘導木聚醣酶之誘導取代物，如山毛櫸木聚醣、小麥麩皮、黃豆粉、白楊木，發現10%小麥麩皮所誘導之木聚醣酶活性比使用山毛櫸木聚醣誘導之對照組更高。測試葡萄糖對誘導木聚醣酶之影響，發現葡萄糖並不抑制木聚醣酶生成，且可誘導更多木聚醣酶活性產生。以合成培養基於搖瓶培養後第12小時可獲得12.1 U/mL的木聚醣酶活性，而於發酵槽饋料培養後在第12個小時可獲得最高木聚醣酶活性59.2 U/mL。

Bacillus subtilis natto #14 has the highest xylanase activity which optimum temperature and pH is 50℃ and pH 5. We used synthetic medium with ammonium salts and little yeast extract as nitrogen source. Compared with glucose, sucrose, xylose, and glycerol, the most suitable carbon source in growth stage was glucose. Compared with beechwood xylan, wheat bran, soya powder, and white poplar powder, the best inducer for xylanase production was wheat bran. Induction of xylanase activity by 10% wheat bran was higher than induction by beechwood xylan. While grown with glucose and xylan, we found that glucose would help to induce xylanase activity, instead of inhibition. While grown in synthetic medium by flask culture, we could obtain the xylanase activity with 12.1 U/mL for 12 hours. While grown in bioreactor, we could obtain the highest xylanase activity with 59.2 U/mL for 12 hours.