丙酮／丁醇间歇萃取发酵

为了防止丙酮/丁醇发酵过程中代谢产物丁醇对丙酮/丁醇梭状芽孢杆菌(Closlridium acetobutylicum)的抑制作用,进行了萃取和发酵相结合过程的研究。从十三种有机化合物对丙酮/丁醇梭状芽孢杆菌的毒性以及它们的物理性能出发,选出了油醇和混合醇(油醇和硬脂醇的混合物)作为丙酮/丁醇萃取发酵的萃取剂。和用正交试验考察了以油醇作萃取剂时,发酵温度、初始葡萄糖浓度和油水比等三因素对游离细胞、固定化细胞的无搅拌间歇萃取发酵的影响。根据正交试验结果,研究了发酵温度41/35℃、油水比1∶2和不同初始葡萄糖浓度时的间歇搅拌萃取发酵。当初始葡萄糖浓度为110(g/1)时,发酵结束水相丁醇浓度5.12(g/1)、折合水相丁醇浓度16.27(g/1)、折合水相总溶剂浓度33.63(g/1),发酵过程的葡萄糖利用率98.0％。总浓剂产率0.312。研究结果表明:萃取发酵可以减轻产物丁醇对丙酮/丁醇梭状芽孢杆菌的抑制、提高初始葡萄糖浓度、减少生产过程的废水量,为降低产物分离的能耗和总溶剂的生产成本打下了基础。

Study on acetone/butanol fermentation with in-situ solvent extraction

The extractive batch fermentation for acetone/butanol (ABE) production was studied in this work. The aim of the study is to eliminate or reduce the end product(butanol) inhibition on Clostridium acetobutylicum growth. The toxicity and selectivity of 13 organic compounds were tested. Among them, oleyl alcohol and mixed alcohol (the mixture of oleyl alcohol and C-18 alcohol)were the best for acetone/butanol fermentation. The orthogonal-cross-test method with three elements and three levels was used to evaluate the effects of fermentation temperature, initial glucose concentration, and solvent/water ratio on the extractive batch ABE fermentation. According to the results of the orthogonal-cross-test, the extractive batch ABE fermentation in a stirred fermentor was studied at different initial glucose concentration at 41/35 C and at solvent/water ratio 1:2. When initial glucose concentration is 110 (g/l), at the end of extractive fermentation, the butanol concentration in the broth and in the solvent is 5. 12(g/l) and 22. 3(g/l) respectively,the total butanol concentration based on the broth volume is about 16. 27(g/l), the total ABE concentration based on the broth volume is 33. 63(g/l). The conversion ratio of glucose is 98%, and the total ABE yield is 0. 312. The results show that the in-situ extractive fermentation can eliminate the inhibition of butanol on the microorganism growth, increase the initial glucose concentration, and reduce the wastewater amount. Thus, the comsumption of energy may be reduced for the separation and purification of the products.