中国豆豉与日本纳豆的发酵微生物特性对比研究

Comparative study of fermentation strains about Chinese Douchi and Japanese natto

中文关键词:  细菌型豆豉  纳豆  纤溶酶  葡萄糖苷酶

英文关键词:bacterial Douchi  natto  plasminase  β-glucosidase

中文摘要:

      目的 对比研究中国豆豉与日本纳豆的发酵微生物特性。方法 采集中国陕西、四川、广西、贵州、河南和山东等地方特产豆豉样本, 通过平板筛选、菌苔观察、显微镜鉴别得到目标菌株; 采用改进的蛋白纤维平板法测定纳豆激酶活性, 采用硝基苯酚显色法测定β-葡萄糖苷酶活性; 采用同日本纳豆的发酵工艺, 液体培养筛得的枯草芽孢杆菌种子液, 固体发酵大豆产物, 其发酵物与纳豆的外观、嗅味和酶活性进行对比。结果 国内细菌型豆豉的微生物以枯草类芽孢杆菌丰度最高; 其菌苔褶皱、凸起、透明、拉丝有黏性; 其发酵大豆产物的外观、性状、嗅味与纳豆高度一致, 纤溶酶活性范围为1700~12000 U/g; 豆豉中的霉菌具有β-葡萄糖苷酶活性, 而枯草芽孢杆菌不分泌β-葡萄糖苷酶。结论 中国细菌型豆豉的主要发酵菌株是枯草芽孢杆菌, 有些菌株的纤溶酶活性高于日本的纳豆芽孢杆菌; 有的豆豉样本中留存参与发酵的霉菌, 具有β-葡萄糖苷酶活性, 参与分解大豆黄酮苷成分; 日本的纳豆起源于中国的细菌型豆豉, 具有菌株明晰、无辅料和过程简化易控等优点。

英文摘要:

      Objective To compartive study of fermentaion staina about Chinese Douchi and Japanese natto. Methods The samples of Douchi from Shaanxi, Sichuan, Guangxi, Guizhou, Henan and Shandong were collected, and the strains of target strain were identified by plate screening, bacterial coating observation and microscope. The nattokinase activity was determined by the modified protein fiber plate method, and the β-glucosidase activity was determined by the nitrophenol chromogenic method. Using the same fermentation process as Japanese natto, the liquid culture screening of Bacillus subtilis seed solution, solid-state fermentation of soybean, the fermentation products were compared with natto in appearance, smell and enzyme activity. Results The predominant microorganism in domestic bacterial Douchi was Bacillus subtilis; its bacterial film was wrinkled, protruding transparent, and sticky; the appearance, texture, and smell of its Douchi products were highly consistent with natto, and the activity range of plasmin was from 1700 to 12000 U/g. The mold in tempeh had β-glucosidase activity, which Bacillus subtilis did not secrete β-glucosidase. Conclusion Bacillus subtilis is the main fermentation strain of Chinese bacterial Douchi, and some strains has higher plasminase activity than Bacillus natto of Japan. Some Douchi mold remained in the samples, which has β-glucosidase activity and participated in the decomposition of daidzein glycosides. Natto in Japan originated from the Douchi in China, which has the advantages of clear strains, no excipients and easy control of the process.