Tada Shiori, Katakura Yoshio, Ninomiya Kazuaki, Shioya Suteaki
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Biosci Bioeng. 2007 Jun;103(6):557-62. doi: 10.1263/jbb.103.557.
In a batch coculture of kefiran-producing lactic acid bacteria Lactobacillus kefiranofaciens and lactate-assimilating yeast Saccharomyces cerevisiae, lactate accumulation in the medium was observed, which inhibited kefiran production. To enhance kefiran productivity by preventing lactate accumulation, we conducted lactose-feeding batch operation with feedforward/feedback control during the coculture, so that the lactate production rate of L. kefiranofaciens was balanced with the lactate consumption rate of S. cerevisiae. The lactate concentration was maintained at less than 6 g l(-1) throughout the fed-batch coculture using a 5 l jar fermentor, although the concentration reached 33 g l(-1) in the batch coculture. Kefiran production was increased to 6.3 g in 102 h in the fed-batch coculture, whereas 4.5 g kefiran was produced in 97 h in the batch coculture. The kefiran yield on lactose basis was increased up to 0.033 g g(-1) in the fed-batch coculture, whereas that in the batch coculture was 0.027 g g(-1).
在产生开菲尔多糖的乳酸菌开菲尔糖乳杆菌与同化乳酸的酵母酿酒酵母的分批共培养中，观察到培养基中有乳酸积累，这抑制了开菲尔多糖的产生。为了通过防止乳酸积累来提高开菲尔多糖的生产率，我们在共培养期间进行了乳糖补料分批操作，并采用前馈/反馈控制，以使开菲尔糖乳杆菌的乳酸产生速率与酿酒酵母的乳酸消耗速率保持平衡。使用5升罐式发酵罐进行补料分批共培养时，乳酸浓度在整个过程中均维持在6 g l(-1)以下，而在分批共培养中该浓度达到了33 g l(-1)。补料分批共培养中，在102小时内开菲尔多糖产量增加到6.3 g，而分批共培养中在97小时内产生了4.5 g开菲尔多糖。基于乳糖的开菲尔多糖产率在补料分批共培养中提高到了0.033 g g(-1)，而在分批共培养中为0.027 g g(-1)。
