Guo F, Zheng H, Cheng Y, Song S, Zheng Z, Jia S
Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.
Lett Appl Microbiol. 2018 Feb;66(2):124-131. doi: 10.1111/lam.12812. Epub 2018 Jan 9.
Poly-ε-L-lysine is a natural homo-polyamide of L-lysine with excellent antimicrobial properties, which can be used as a novel preservative and has a wide range of applications. In this paper, the fermentation medium for ε-PL production by Streptomyces diastatochromogenes 6#-7 was optimized by Response Surface Methodology. The results of Plackett-Burman design showed that glucose, yeast extract and (NH ) SO were the major influencing factors in ε-PL production of S. diastatochromogenes 6#-7. The optimal concentrations of glucose, yeast extract and (NH ) SO were determined to be 60, 7·5 and 7·5 g l according to Box-Behnken experiment and regression analysis, respectively. Under the optimized conditions, the ε-PL yield in shake-flask fermentation was 0·948 ± 0·030 g l , which was in good agreement with the predicted value of 0·970 g l . The yield was improved by 43·1% from that with the initial medium. In 5 l jar-fermenter the ε-PL yield reached 25·5 g l , which was increased by 56·4% from the original medium. In addition, the fermentation time was reduced from 174 to 120 h.
Medium optimization is a very practical and valuable tool for fermentation industry to improve product yield and minimize by-products as well as reduce overall manufacturing costs. The response surface methodology is not new, but it is still a very effective method in medium optimization research. This study used ε-polylysine fermentation as an example to demonstrate how the product yield can be significantly increased by medium optimization through surface response methodology. Similar approach can be used in other microbial fermentations such as in pharmaceutical, food, agricultural and energy industries. As an example, ε-polylysine is one of a few newly approved natural food-grade antimicrobials for food and beverages preservations. Yield improvement is economically beneficial to not only ε-polylysine manufacturers but also to their users and consumers due to lower costs and price.
聚-ε-L-赖氨酸是L-赖氨酸的一种天然同聚酰胺，具有优异的抗菌性能，可作为新型防腐剂，应用广泛。本文采用响应面法对产淀粉酶链霉菌6#-7生产ε-PL的发酵培养基进行了优化。Plackett-Burman设计结果表明，葡萄糖、酵母提取物和(NH₄)₂SO₄是影响产淀粉酶链霉菌6#-7生产ε-PL的主要因素。根据Box-Behnken实验和回归分析，确定葡萄糖、酵母提取物和(NH₄)₂SO₄的最佳浓度分别为60、7.5和7.5 g/L。在优化条件下，摇瓶发酵中ε-PL产量为0.948±0.030 g/L，与预测值0.970 g/L吻合良好。与初始培养基相比，产量提高了43.1%。在5 L罐式发酵罐中，ε-PL产量达到25.5 g/L，比原始培养基提高了56.4%。此外，发酵时间从174小时缩短至120小时。
培养基优化是发酵工业提高产品产量、减少副产物以及降低总体生产成本的一种非常实用且有价值的工具。响应面法虽不新颖，但在培养基优化研究中仍是一种非常有效的方法。本研究以ε-聚赖氨酸发酵为例，展示了如何通过表面响应法进行培养基优化来显著提高产品产量。类似方法可用于其他微生物发酵，如制药、食品、农业和能源行业。例如，ε-聚赖氨酸是少数几种新批准的用于食品和饮料保鲜的天然食品级抗菌剂之一。产量提高不仅对ε-聚赖氨酸制造商有利，对其使用者和消费者也经济有益，因为成本和价格降低了。
