RT Journal Article SR Electronic(1) A1 Feng, Xueyang A1 Bandyopadhyay, Anindita A1 Berla, Bert A1 Page, Lawrence A1 Wu, Bing A1 Pakrasi, Himadri B. A1 Tang, Yinjie J.YR 2010 T1 Mixotrophic and photoheterotrophic metabolism in Cyanothece sp. ATCC 51142 under continuous light JF Microbiology, VO 156 IS 8 SP 2566 OP 2574 DO https://doi.org/10.1099/mic.0.038232-0 PB Microbiology Society, SN 1465-2080, AB 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 13C-assisted metabolite analysis and biochemical measurements. Under continuous light (50 μmol 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 μmol H2 (mg chlorophyll) −1 h−1], but strongly reduced phototrophic CO2 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 CO2 via anaplerotic pathways, and to take up glucose and pyruvate for mixotrophic biomass synthesis., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.038232-0