Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, Jiangsu, China.
Bioprocess Biosyst Eng. 2011 Jun;34(5):561-7. doi: 10.1007/s00449-010-0505-8. Epub 2011 Jan 7.
The production of ε-poly-L: -lysine (ε-PL) by Streptomyces sp. M-Z18 from glycerol was investigated in a 5-L jar-fermenter. Batch fermentations by Streptomyces sp. M-Z18 at various pH values ranging from 3.5 to 4.5 were studied. Based on the analysis of the time course of specific cell growth rate and specific ε-PL formation rate, a novel two-stage pH control strategy was developed to improve ε-PL production by shifting the culture pH from 3.5 to 3.8 after 36 h of cultivation. By applying the strategy, the maximal ε-PL concentration and productivity had a significant improvement and reached 9.13 g L(-1) and 4.76 g L(-1) day(-1), respectively, compared with those in one-stage pH control process where the pH value is controlled at 3.5 (7.83 g L(-1) and 3.13 g L(-1) day(-1)). Fed-batch fermentation with two-stage pH control strategy was also applied to produce ε-PL; final ε-PL concentration of 30.11 g L(-1) was obtained, being 3.3-fold greater than that of batch fermentation. To our knowledge, it is the first report on production of ε-PL from glycerol in fermenter scale and achievement of high ε-PL production with two-stage pH control strategy.
采用摇瓶发酵的方法，研究了发酵条件对马杜拉放线菌（Streptomyces sp.）M-Z18 利用甘油生产 ε-聚-L-赖氨酸（ε-PL）的影响。在 3.5~4.5 的不同 pH 值条件下分批发酵，分析了比生长速率和产物合成速率随时间的变化，提出了一种 novel two-stage pH control strategy，即在培养 36 h 后将培养 pH 值由 3.5 调至 3.8。运用该 strategy，ε-PL 的产量和生产强度均得到显著提高，达到 9.13 g·L(-1)和 4.76 g·L(-1)·d(-1)，与 pH 控制在 3.5 的 one-stage pH control process（7.83 g·L(-1)和 3.13 g·L(-1)·d(-1)）相比，分别提高了 18.3%和56.2%。采用 two-stage pH control strategy 进行补料分批发酵，ε-PL 的浓度达到 30.11 g·L(-1)，是 batch fermentation 的 3.3 倍。据我们所知，这是首次在发酵罐规模上利用甘油生产 ε-PL，同时也是首次采用 two-stage pH control strategy 实现了高产量的 ε-PL 生产。
