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Biotechnol J. 2018 Jul;13(7):e1700497. doi: 10.1002/biot.201700497. Epub 2018 Mar 26.

Genome Variations of Evolved Escherichia coli ET8 With a Rhodopsin-Based Phototrophic Metabolism.

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Hana Academy Seoul, Seoul, Republic of Korea.
Department of Biological Sciences, Seoul National University, Seoul, Korea.
Department of Systems Biotechnology, Chung-Ang University, Anseong, Gyeonggi, Republic of Korea.
Department of Biotechnology, the Catholic University of Korea, Bucheon, Gyeonggi, Republic of Korea.
Department of Life Science, Sogang University, Seoul, Republic of Korea.
Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.


We reported that the phototrophic metabolism via plasmid-originated Gloeobacter rhodopsin(GR)-expression is improved in Escherichia coli ET5 harboring pKJ606-GR by a genomic point mutation (dgcQC1082A ) encoding a transmembrane cell signaling protein (Microb. Cell Fact. 16:111, 2017). Another evolved descendant is isolated from the chemostat, and the genome variation of the strain named ET8 harboring pKJ606-GR is investigated in this study. Whole genome sequencing analysis identifies a single point mutation (C3831976A) located in the non-coding upstream region of kdtA and an IS4 insertional mutation at galUG706 without any mutations in the plasmid. ET8 strain shows enhanced kdtA transcription and no growth in the D-galactose or lactose sole carbon sourced minimal media. Size of ET8 strain are almost identical to that of the ancestor. Phototrophic growth and proton pumping in ET8 expressing GR (ET8 + GR) are increased 1.5-fold and threefold, respectively, compared with those in the ancestor (W3110 + GR). To verify the effects of the genomic mutations, either the kdtA-upregulation or the galU-disruption is conducted in the ancestor. Both the kdtA-upregulation and the galU-disruption result in the drastic increases of proton-pumping. The physiological properties arising from the genomic variations of the evolved host with the new phototrophic metabolism are further discussed.


Gloeobacter rhodopsin; adaptive laboratory evolution; chemotroph; galU-disruption; kdtA-upregulation; phototroph

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