Research and Development Center of Biorational Pesticides, Northwest A & F University, Yangling Shaanxi, PR China.
Bioresour Technol. 2010 Oct;101(19):7529-36. doi: 10.1016/j.biortech.2010.04.070. Epub 2010 May 21.
To evaluate the effects of dissolved oxygen (DO) control strategy on cell growth and the production of antibiotic (cyclo(2-Me-BABA-Gly)) by Xenorhabdus nematophila. The effects of different agitation speeds and DO concentrations on cell growth and antibiotic activity of X. nematophila YL001 were examined. Experiments showed that higher agitation speeds and DO concentrations at earlier fermentation stage were favorable for cell growth and antibiotic production. At mid- and later-stage, properly decreasing DO concentration can strengthen cell growth and antibiotic production. Based on the kinetic information about the effects of agitation speeds and DO concentrations on the fermentation, the two-stage DO control strategy in which DO concentration was controlled to 70% in the first 18 h, and then switched to 50% after 18 h, was established to improve the biomass and antibiotic activity. By applying this DO-shift strategy in X. nematophila YL001 fermentation, maximal antibiotic activity and biomass reached 252.0+/-6.10 U/mL and 30.04+/-2.50 g/L, respectively, thus was 18.99% and 15.36% more than in the cultures at constantly 50% DO.
为了评估溶解氧（DO）控制策略对细胞生长和抗生素（环（2-Me-BABA-Gly））产生的影响，本研究考察了不同搅拌速度和 DO 浓度对嗜线虫致病杆菌 X. nematophila YL001 细胞生长和抗生素活性的影响。实验表明，在发酵早期，较高的搅拌速度和 DO 浓度有利于细胞生长和抗生素的产生。在中晚期，适当降低 DO 浓度可以增强细胞生长和抗生素的产生。基于搅拌速度和 DO 浓度对发酵影响的动力学信息，建立了两阶段 DO 控制策略，即在最初的 18 小时内将 DO 浓度控制在 70%，然后在 18 小时后切换至 50%，以提高生物量和抗生素活性。在 X. nematophila YL001 发酵中应用这种 DO 转换策略，最大抗生素活性和生物量分别达到 252.0+/-6.10 U/mL 和 30.04+/-2.50 g/L，分别比在恒定 50% DO 下的培养物提高了 18.99%和 15.36%。
