Kouya Tomoaki, Tobita Kazuhiro, Horiuchi Masahito, Nakayama Eri, Deguchi Hiroyoshi, Tanaka Takaaki, Taniguchi Masayuki
Department of Materials Science and Technology, Faculty of Engineering, Niigata University, Ikarashi 2, Nishi-ku, Niigata 950-2181, Japan.
J Biosci Bioeng. 2008 Mar;105(3):184-91. doi: 10.1263/jbb.105.184.
Production of a bifidogenic growth stimulator (BGS) by Propionibacterium freudenreichii subsp. shermanii (Propionibacterium shermanii) using lactic acid as a carbon source was investigated using different cultivation methods. When a continuous bioreactor system with a filtration device was used at a dilution rate of 0.075 h(-1), the average BGS concentration was 2.4 mg/l, which corresponds to a BGS productivity per cultivation time of 1.8 x 10(-1) mg x l(-1) x h(-1). The BGS productivity per cultivation time in continuous cultivation with filtration was 1.9-fold that (9.4 x 10(-2) mg x l(-1).h(-1)) in a conventional batch cultivation. In fed-batch cultivation with feed-back control using an on-line lactic acid controller with a lactic acid biosensor, it was possible to prevent substrate inhibition by maintaining the lactic acid concentration in culture broth low at 3.3 g/l, and an enhanced BGS production (31 mg/l) was successfully attained. The BGS productivity per cultivation time (2.1x10(-1) mg x l(-1) x h(-1)) in the fed-batch cultivation with feed-back control was 2.2-fold that in the conventional batch cultivation. A new bioreactor system was developed by coupling a continuous bioreactor system with a filtration device to an on-line lactic acid controller. Using the new bioreactor system, we produced BGS continuously at a high level of 47 mg/l. The BGS productivities per cultivation time (3.5 mg.l(-1) x h(-1)) and the total volume of medium used (1.7 x 10(-1) mg x l(-1) x h(-1)) obtained in the new bioreactor system were 37-fold and 2.1-fold those in the conventional batch cultivation, respectively. These results described above clearly demonstrate the positive effects of both the continuous filtration for removal of metabolites (propionic and acetic acids) inhibitory to cell growth and feed-back control of lactic acid concentration in the culture broth on BGS production by P. shermanii. This paper is the first report on BGS production by the propionic acid bacterium using lactic acid as a carbon source.
研究了费氏丙酸杆菌谢氏亚种（丙酸杆菌谢氏亚种）以乳酸为碳源生产双歧生长刺激因子（BGS）的不同培养方法。当使用带有过滤装置的连续生物反应器系统，稀释率为0.075 h⁻¹时，BGS的平均浓度为2.4 mg/L，这相当于每培养时间的BGS生产率为1.8×10⁻¹ mg·L⁻¹·h⁻¹。连续过滤培养中每培养时间的BGS生产率是传统分批培养中（9.4×10⁻² mg·L⁻¹·h⁻¹）的1.9倍。在使用带有乳酸生物传感器的在线乳酸控制器进行反馈控制的补料分批培养中，通过将培养液中的乳酸浓度维持在3.3 g/L的低水平，可以防止底物抑制，并成功实现了BGS产量的提高（31 mg/L）。反馈控制补料分批培养中每培养时间的BGS生产率（2.1×10⁻¹ mg·L⁻¹·h⁻¹）是传统分批培养的2.2倍。通过将带有过滤装置的连续生物反应器系统与在线乳酸控制器耦合，开发了一种新的生物反应器系统。使用新的生物反应器系统，我们连续生产了高水平的47 mg/L的BGS。新生物反应器系统中获得的每培养时间的BGS生产率（3.5 mg·L⁻¹·h⁻¹）和所用培养基的总体积（1.7×10⁻¹ mg·L⁻¹·h⁻¹）分别是传统分批培养的37倍和2.1倍。上述结果清楚地表明，连续过滤去除抑制细胞生长的代谢物（丙酸和乙酸）以及对培养液中乳酸浓度进行反馈控制对谢氏丙酸杆菌生产BGS具有积极作用。本文是关于丙酸杆菌以乳酸为碳源生产BGS的首次报道。
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