title: Anionic metabolite biosynthesis enhanced by potassium under dark, anaerobic conditions in cyanobacteria.
abstract: Potassium (K(+)) is an essential macronutrient for all living organisms including cyanobacteria. Cyanobacteria are a group of bacteria performing oxygenic photosynthesis, widely studied in basic and applied sciences. The primary metabolism of the unicellular cyanobacterium Synechocystis sp. PCC 6803 is altered by environmental conditions, and it excretes organic acids and hydrogen under dark, anaerobic conditions. Here we demonstrated that K(+) widely changes the primary carbon metabolism of this cyanobacterium. Succinate and lactate excretion from the cells incubated under dark, anaerobic conditions was enhanced in the presence of K(+), while hydrogen production was repressed. The addition of K(+) and the genetic manipulation of acetate kinase AckA and an RNA polymerase sigma factor SigE additively increased succinate and lactate production to 141.0 and 217.6 mg/L, which are 11 and 46 times, compared to the wild-type strain without K(+), respectively. Intracellular levels of 2-oxoglutarate, succinate, fumarate, and malate increased by K(+) under dark, anaerobic conditions. This study provides the evidence of the considerable effect of K(+) on the biosynthesis of anionic metabolites in a unicellular cyanobacterium.
authors: School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors: Sakiko
authors: S
authors: Ueda
authors: School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors: Yuhki
authors: Y
authors: Kawamura
authors: School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors: Hiroko
authors: H
authors: Iijima
authors: School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors: Mitsuharu
authors: M
authors: Nakajima
authors: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors: Tomokazu
authors: T
authors: Shirai
authors: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors: Mami
authors: M
authors: Okamoto
authors: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.|Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokkodai, Nada, Kobe 657-8501, Japan.
authors: Akihiko
authors: A
authors: Kondo
authors: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors: Masami Yokota
authors: MY
authors: Hirai
authors: School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.|RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors: Takashi
authors: T
authors: Osanai
mesh_terms: D000693:Anaerobiosis / Q000235:genetics; D000838:Anions / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006859:Hydrogen / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D011188:Potassium / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D000838:Anions; D001426:Bacterial Proteins; D012808:Sigma Factor; C111259:sigE protein, Bacteria; D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen; D011188:Potassium