Biebl H, Zeng A P, Menzel K, Deckwer W D
GBF-Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, Germany.
Appl Microbiol Biotechnol. 1998 Jul;50(1):24-9. doi: 10.1007/s002530051251.
Klebsiella pneumoniae was shown to convert glycerol to 1,3-propanediol, 2,3-butanediol and ethanol under conditions of uncontrolled pH. Formation of 2,3-butanediol starts with some hours' delay and is accompanied by a reuse of the acetate that was formed in the first period. The fermentation was demonstrated in the type strain of K. pneumoniae, but growth was better with the more acid-tolerant strain GT1, which was isolated from nature. In continuous cultures in which the pH was lowered stepwise from 7.3 to 5.4, 2,3-butanediol formation started at pH 6.6 and reached a maximum yield at pH 5.5, whereas formation of acetate and ethanol declined in this p range 2,3-Butanediol and acetoin were also found among the products in chemostat cultures grown at pH 7 under conditions of glycerol excess but only with low yields. At any of the pH values tested, excess glycerol in the culture enhanced the butanediol yield. Both effects are seen as a consequence of product inhibition, the undissociated acid being a stronger trigger than the less toxic diols and acid anions. The possibilities for using the fermentation type described to produce 1,3-propanediol and 2,3-butanediol almost without by-products are discussed.
在pH值未控制的条件下，肺炎克雷伯菌可将甘油转化为1,3 - 丙二醇、2,3 - 丁二醇和乙醇。2,3 - 丁二醇的形成会延迟数小时开始，并伴随着第一阶段形成的乙酸盐的再利用。该发酵过程在肺炎克雷伯菌的模式菌株中得到证实，但从自然界分离得到的更耐酸的GT1菌株生长得更好。在连续培养中，pH值从7.3逐步降低到5.4，2,3 - 丁二醇的形成在pH 6.6时开始，并在pH 5.5时达到最大产量，而在此pH范围内，乙酸盐和乙醇的形成减少。在甘油过量的条件下，在pH 7下进行恒化培养时，产物中也发现了2,3 - 丁二醇和乙偶姻，但产量较低。在任何测试的pH值下，培养物中过量的甘油都会提高丁二醇的产量。这两种效应都被视为产物抑制的结果，未解离的酸比毒性较小的二醇和酸阴离子是更强的触发因素。文中讨论了利用所述发酵类型几乎无副产物地生产1,3 - 丙二醇和2,3 - 丁二醇的可能性。
