期刊
PROCESS BIOCHEMISTRY
卷 62, 期 -, 页码 53-58出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.procbio.2017.09.001
关键词
CS dicarboxylic acids; Synthetic biology; Metabolic engineering; Aerobic-anaerobic shift fermentation; Anaerobically-inducible promoter
资金
- National Natural Science Foundation of China [21406138, 31370083]
- Program of Shanghai Subject Chief Scientist from the Science and Technology Commission of Shanghai Municipality [14XD1402600]
- National Basic Research Program of China [2013CB733903]
- Open Funding Project of the State Key Laboratory of Bioreactor Engineering
Synthetic biology provides a significant platform in creating novel pathways/organisms for producing useful compounds, while it remains a challenge to enhance the production efficiency. Recently we constructed a recombinant Escherichia coli for glutarate production using a synthetic alpha-ketoacid reduction pathway, in which aketoglutarate is reduced to 2-hydroxyglutarate then converted to glutarate. However, the production titer was low, which may be due to 1) oxygen-sensitive nature of 2-hydroxyglutaryl-CoA dehydratase (HgdABC) and 2) limited cell growth in anaerobic cultivation. Therefore, we developed an aerobic-anaerobic two-stage strategy by growing more cells aerobically, then shifting to anaerobic cultivation to ensure the functional HgdABC for glutarate biosynthesis. The two-stage cultivation resulted in higher production of glutarate and other two C5 dicarboxylic acids glutaconate and 2-hydroxylglutarate than the original anaerobic process. Furthermore, we used an anaerobically-inducible nar promoter to improve the hgdABC expression responding to aerobic-anaerobic shift. Finally, the glutarate, glutaconate and 2-hydroxyglutarate titer was increased about 2, 5 and 3 times, reaching 11.6, 108.8 and 399.5 mg/L, respectively. The work demonstrated an effective strategy for ameliorating a-ketoacid reduction pathway to produce C5 dicarboxylic acids, as well as the potential of integration of bioprocess and metabolic engineering for enhancing chemicals production by an engineered microorganism.
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