期刊
METABOLIC ENGINEERING
卷 43, 期 -, 页码 85-91出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ymben.2017.07.001
关键词
Membrane engineering; Production; Terpenoids; beta-Carotene; Escherichia coli
资金
- National Natural Science Foundation of China [31522002]
- National High Technology Research and Development Program of China [2015AA020202]
- Tianjin Key Technology R & D program of Tianjin Municipal Science and Technology Commission [14ZCZDSY00067]
- Novo Nordisk-Chinese Academy of Sciences (NN-CAS) Research Fund [NNCAS-2015-2]
Carotenoids are a class of terpenes of commercial interest that exert important biological functions. While various strategies have been applied to engineer beta-carotene production in microbial cell factories, no work has been done to study and improve the storage of hydrophobic terpene products inside the heterologous host cells. Although the membrane is thought to be the cell compartment that accumulates hydrophobic terpenes such as beta-carotene, direct evidence is still lacking. In this work, we engineered the membrane of Escherichia coli in both its morphological and biosynthetic aspects, as a means to study and improve its storage capacity for beta-carotene. Engineering the membrane morphology by overexpressing membrane-bending proteins resulted in a 28% increase of beta-carotene specific producton value, while engineering the membrane synthesis pathway led to a 43% increase. Moreover, the combination of these two strategies had a synergistic effect, which caused a 2.9-fold increase of beta-carotene specific production value (from 6.7 to 19.6 mg/g DCW). Inward membrane stacks were observed in electron microscopy images of the engineered E. coli cells, which indicated that morphological changes were associated with the increased beta-carotene storage capacity. Finally, membrane separation and analysis confirmed that the increased beta-carotene was mainly accumulated within the cell membrane. This membrane engineering strategy was also applied to the beta-carotene hyperproducing strain CAR025, which led to a 39% increase of the already high beta-carotene specific production value (from 31.8 to 44.2 mg/g DCW in shake flasks), resulting in one of the highest reported specific production values under comparable culture conditions. The membrane engineering strategy developed in this work opens up a new direction for engineering and improving microbial terpene producers. It is quite possible that a wide range of strains used to produce hydrophobic compounds can be further improved using this novel engineering strategy.
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