Department of Chemical Engineering, Hanyang University, 17 Hangdang-dong, Seongdong-gu, Seoul 133-791, Republic of Korea.
Enzyme Microb Technol. 2013 Aug 15;53(3):143-51. doi: 10.1016/j.enzmictec.2013.02.008. Epub 2013 Feb 26.
Clostridium sp. BS-1 produces hexanoic acid as a metabolite using galactitol and enhanced hexanoic acid production was obtained by in situ extractive fermentation with Clostridium sp. BS-1 under an optimized medium composition. For medium optimization, five ingredients were selected as variables, and among them yeast extract, tryptone, and sodium butyrate were selected as significant variables according to a fractional factorial experimental design, a steepest ascent experimental design, and a Box-Behnken experimental design. The optimized medium had the following compositions in modified Clostridium acetobutyricum (mCAB) medium: 15.5gL(-1) of yeast extract, 10.13gL(-1) of tryptone, 0.04gL(-1) of FeSO4·7H2O, 0.85gL(-1) of sodium acetate, and 6.47gL(-1) of sodium butyrate. The predicted concentration of hexanoic acid with the optimized medium was 6.98gL(-1), and this was validated experimentally by producing 6.96gL(-1) of hexanoic acid with Clostridium sp. BS-1 under the optimized conditions. In situ extractive fermentation for hexanoic acid removal was then applied in a batch culture system with the optimized medium and 10% (v/v) alamine 336 in oleyl alcohol as an extractive solvent. The pH of the culture in the extractive fermentation was maintained at 5.4-5.6 by an acid balance between production and retrieval by extraction. During a 16 day culture, the hexanoic acid concentration in the solvent increased to 32gL(-1) while it was maintained in a range of 1-2gL(-1) in the medium. The maximum rate of hexanoic acid production was 0.34gL(-1)h(-1) in in situ extractive fermentation.
梭菌 BS-1 利用半乳糖醇生产己酸作为代谢物，通过在优化的培养基组成下，用梭菌 BS-1 进行原位萃取发酵，可获得增强的己酸生产。为了进行培养基优化，选择了五种成分作为变量，根据分因子实验设计、最陡爬坡实验设计和 Box-Behnken 实验设计，选择酵母提取物、胰蛋白胨和丁酸钠作为显著变量。优化后的培养基在改良丙酮丁醇梭菌（mCAB）培养基中的组成如下：酵母提取物 15.5g/L、胰蛋白胨 10.13g/L、FeSO4·7H2O 0.04g/L、乙酸钠 0.85g/L 和丁酸钠 6.47g/L。用优化后的培养基预测的己酸浓度为 6.98g/L，通过在优化条件下用梭菌 BS-1 生产 6.96g/L 的己酸进行实验验证。然后，在优化的培养基和 10%（v/v）油醇中的三辛胺 336 作为萃取溶剂的分批培养系统中应用原位萃取发酵去除己酸。通过萃取的生产和回收之间的酸平衡，将萃取发酵中培养物的 pH 值维持在 5.4-5.6。在 16 天的培养过程中，溶剂中的己酸浓度增加到 32g/L，而在培养基中维持在 1-2g/L 的范围内。原位萃取发酵中己酸的最大生产速率为 0.34g/L·h。
