AUTHOR=Osanai Takashi , Shirai Tomokazu , Iijima Hiroko , Nakaya Yuka , Okamoto Mami , Kondo Akihiko , Hirai Masami Y. 

TITLE=Genetic manipulation of a metabolic enzyme and a transcriptional regulator increasing succinate excretion from unicellular cyanobacterium

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01064

DOI=10.3389/fmicb.2015.01064

ISSN=1664-302X

ABSTRACT=<p>Succinate is a building block compound that the U.S. Department of Energy (DOE) has declared as important in biorefineries, and it is widely used as a commodity chemical. Here, we identified the two genes increasing succinate production of the unicellular cyanobacterium <italic>Synechocystis</italic> sp. PCC 6803. Succinate was excreted under dark, anaerobic conditions, and its production level increased by knocking out <italic>ackA</italic>, which encodes an acetate kinase, and by overexpressing <italic>sigE</italic>, which encodes an RNA polymerase sigma factor. Glycogen catabolism and organic acid biosynthesis were enhanced in the mutant lacking <italic>ackA</italic> and overexpressing <italic>sigE</italic>, leading to an increase in succinate production reaching five times of the wild-type levels. Our genetic and metabolomic analyses thus demonstrated the effect of genetic manipulation of a metabolic enzyme and a transcriptional regulator on succinate excretion from this cyanobacterium with the data based on metabolomic technique.</p>