Department of Chemical Engineering, The University of Michigan, Ann Arbor, Michigan 48109.
Appl Environ Microbiol. 1988 Jul;54(7):1662-7. doi: 10.1128/aem.54.7.1662-1667.1988.
Extractive fermentation has been proposed to enhance the productivity of fermentations that are end product inhibited. Unfortunately, good extractants for butanol, such as decanol, are toxic to Clostridium acetobutylicum. The use of mixed extractants, namely, mixtures of toxic and nontoxic coextractants, was proposed to circumvent this toxicity. Decanol appeared to inhibit butanol formation by C. acetobutylicum when present in a mixed extractant that also contained oleyl alcohol. However, maintenance of the pH at 4.5 alleviated the inhibition of butanol production and the consumption of butyrate during solventogenesis. A mixed extractant that contained 20% decanol in oleyl alcohol enhanced butanol formation by 72% under pH-controlled conditions. The production of acetone and acetoin was also increased, even though these two products were not extractable. The enhancement of butanol formation was not limited by the toxicity of decanol. Supplementation of glucose and butyrate in the extractive fermentation yielded a 47% increase in butanol. The enhancement of butanol formation appeared to be dependent on the presence of dissolved decanol in the broth but was not observed unless an organic phase was present to extract butanol. A mechanism for the effects of decanol on product formation is proposed.
萃取发酵已被提议用于提高受终产物抑制的发酵的生产力。不幸的是，丁醇的良好萃取剂，如癸醇，对丙酮丁醇梭菌有毒。使用混合萃取剂，即有毒和无毒共萃取剂的混合物，被提议来规避这种毒性。癸醇似乎通过在含有油醇的混合萃取剂中存在而抑制丙酮丁醇梭菌的丁醇形成。然而，在溶剂形成过程中保持 pH 值在 4.5 缓解了丁醇产生和丁酸盐的消耗的抑制。在 pH 控制条件下，含有 20%癸醇的油醇混合萃取剂将丁醇的形成提高了 72%。即使这两种产品不可提取，丙酮和乙酰基丁酮的产量也增加了。丁醇形成的增强不受癸醇毒性的限制。在萃取发酵中补充葡萄糖和丁酸盐可使丁醇产量增加 47%。丁醇形成的增强似乎取决于在发酵液中存在溶解的癸醇，但除非存在有机相来提取丁醇，否则不会观察到。提出了癸醇对产物形成的影响的机制。
