CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
Biotechnol Lett. 2023 Sep;45(9):1147-1157. doi: 10.1007/s10529-023-03378-8. Epub 2023 Jun 21.
Docosahexaenoic acid (DHA) is an important omega-3 unsaturated fatty acid and has been widely applied in medicine, food additives, and feed ingredients. The fermentative production of DHA using microorganisms, including Schizochytrium sp., attracted much attention due to its high production efficiency and environment friendly properties. An efficient laboratory evolution approach was used to improve the strain's performance in this study.
A multi-pronged laboratory evolution approach was applied to evolve high-yield DHA-producing Schizochytrium strain. We further employed comparative transcriptional analysis to identify transcriptional changes between the screened strain HS01 and its parent strain GS00.
After multiple generations of ALE, a strain HS01 with higher DHA content and lower saturated fatty acids content was obtained. Low nitrogen conditions were important for enhancing DHA biosynthesis in HS01. The comparative transcriptional analysis results indicated that during the fermentation process of HS01, the expression of key enzymes in the glycolysis, the pentose phosphate pathway and the tricarboxylic acid cycle were up-regulated, while the expression of polyketide synthase genes and fatty acid synthesis genes were similar to those in GS00.
The results suggest that the improved DHA production capacity of HS01 is not due to enhancement of the DHA biosynthesis pathway, but rather related to modulation of central metabolism pathways.
二十二碳六烯酸（DHA）是一种重要的ω-3 不饱和脂肪酸，已广泛应用于医学、食品添加剂和饲料成分。由于生产效率高且环境友好，利用微生物（包括裂殖壶菌）发酵生产 DHA 引起了广泛关注。本研究采用一种有效的实验室进化方法来提高菌株的性能。
采用多管齐下的实验室进化方法来进化高产 DHA 的裂殖壶菌菌株。我们进一步采用比较转录组学分析来鉴定筛选出的菌株 HS01 与其亲本菌株 GS00 之间的转录变化。
经过多轮 ALE 后，获得了 DHA 含量更高、饱和脂肪酸含量更低的菌株 HS01。低氮条件对增强 HS01 中的 DHA 生物合成很重要。比较转录组学分析结果表明，在 HS01 的发酵过程中，糖酵解、戊糖磷酸途径和三羧酸循环中的关键酶的表达上调，而多酮合酶基因和脂肪酸合成基因的表达与 GS00 相似。
结果表明，HS01 中 DHA 生产能力的提高不是由于 DHA 生物合成途径的增强，而是与中心代谢途径的调节有关。
