title: Mixotrophic and photoheterotrophic metabolism in Cyanothece sp. ATCC 51142 under continuous light.
abstract: The unicellular diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 (Cyanothece 51142) is able to grow aerobically under nitrogen-fixing conditions with alternating light-dark cycles or continuous illumination. This study investigated the effects of carbon and nitrogen sources on Cyanothece 51142 metabolism via (13)C-assisted metabolite analysis and biochemical measurements. Under continuous light (50 mumol photons m(-2) s(-1)) and nitrogen-fixing conditions, we found that glycerol addition promoted aerobic biomass growth (by twofold) and nitrogenase-dependent hydrogen production [up to 25 mumol H(2) (mg chlorophyll)( -1) h(-1)], but strongly reduced phototrophic CO(2) utilization. Under nitrogen-sufficient conditions, Cyanothece 51142 was able to metabolize glycerol photoheterotrophically, and the activity of light-dependent reactions (e.g. oxygen evolution) was not significantly reduced. In contrast, Synechocystis sp. PCC 6803 showed apparent mixotrophic metabolism under similar growth conditions. Isotopomer analysis also detected that Cyanothece 51142 was able to fix CO(2) via anaplerotic pathways, and to take up glucose and pyruvate for mixotrophic biomass synthesis.
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St Louis, MO 63130, USA.
authors.forename: Xueyang
authors.initials: X
authors.lastname: Feng
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Anindita
authors.initials: A
authors.lastname: Bandyopadhyay
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St Louis, MO 63130, USA.
authors.forename: Bert
authors.initials: B
authors.lastname: Berla
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Page
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St Louis, MO 63130, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.|Department of Energy, Environmental and Chemical Engineering, Washington University, St Louis, MO 63130, USA.
authors.forename: Himadri B
authors.initials: HB
authors.lastname: Pakrasi
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St Louis, MO 63130, USA.
authors.forename: Yinjie J
authors.initials: YJ
authors.lastname: Tang
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D046889:Cyanothece / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D005990:Glycerol / Q000378:metabolism; D052836:Heterotrophic Processes; D008027:Light; D009584:Nitrogen / Q000378:metabolism; D009591:Nitrogenase / Q000378:metabolism; D010788:Photosynthesis; D052817:Phototrophic Processes
chemical_list: D002247:Carbon Isotopes; D002244:Carbon; D009591:Nitrogenase; D009584:Nitrogen; D005990:Glycerol