Project description:Rhodobacter sphaeroides produces hydrogen gas (H2) via its nitrogenase enzyme during photoheterotrophic growth under nitrogen-limited conditions. We find that cells produce different amounts of H2 and show different growth rates, depending on the organic substrate provided (lactate, succinate, glucose, xylose, or glycerol). We used global transcript analyses to determine what genes are involved in the onset of H2 production, and those that lead to different H2 production capacities in cells fed different organic substrates. Growth and real-time H2 production were followed for photoheterotrophically grown Rhodobacter sphaeroides cultures (19 mL test tube cultures) fed one of five different organic substrates (lactate, succinate, glucose, xylose, or glycerol) and provided glutamate as the sole nitrogen source. Cells were harvested for RNA extraction during early post-exponential growth, at points near the maximum H2 production rates of the cultures. Non-H2-producing cells (500 mL cultures) fed succinate and provided NH4+ as nitrogen source were also harvested for RNA extraction as reference samples. At least two samples for every given set of conditions were analyzed.
Project description:Rhodobacter sphaeroides produces hydrogen gas (H2) via its nitrogenase enzyme during photoheterotrophic growth under nitrogen-limited conditions. We find that cells produce different amounts of H2 and show different growth rates, depending on the organic substrate provided (lactate, succinate, glucose, xylose, or glycerol). We used global transcript analyses to determine what genes are involved in the onset of H2 production, and those that lead to different H2 production capacities in cells fed different organic substrates.
Project description:mRNA levels were measured in Rhodobacter sphaeroides 2.4.1 at 20% O2 and 0.5% O2, Rhodobacter sphaeroides 2.4.1 App11 (AppA-null), Rhodobacter sphaeroides 2.4.1 (pPNs) and PpsR mutant PPS2-4. The mRNA samples were prepared from cultures supplied with 20% O2, 1% CO2, and 79% N2, and grown in the dark to an OD of 0.18. The mRNA levels for each strain was measured three times. Keywords: repeat sample
