(495e) Thermus Thermophilus As a Thermophilic Model Organism for Biofuels Production

The growth of Thermus thermophilus HB8, a thermophilic bacterium, was characterized in batch cultures under defined experimental growth conditions. First, the defined growth medium was optimized to maximize the growth rate without the need to add yeast extract to the medium. After that, growth rates were measured under aerobic growth conditions for temperatures ranging between 50 C and 90 C with glucose as the only carbon source. The optimum growth temperature was determined to be 85 C. The maximum growth rate of T. thermophilus was 0.28 1/hr, which corresponded to a doubling time of about 2.5 hours. In our growth experiments, T. thermophilus was cultured in custom designed mini-bioreactors at 10-mL scale that were constructed using Hungate tubes and septum caps. We used uniformly 13C-labeled glucose [U-13C]glucose as the carbon source in our experiments and measured [13C]CO2  production in the offgas by an online mass spectrometer (at m/z 45). With this setup we followed the growth of cells in real-time. In addition to measuring CO2 production, we also measured glucose concentration and optical density at 600 nm (OD600) during the cultures. From all of these measurements, we calculated growth rates for the exponential growth phase. We are currently investigating the potential of using T. thermophilus for the production of various biofuels.