Figure 1

Chemostat culture of the C. thermocellum for selection of improved n-butanol tolerance. The strains were grown on MTC-5 minimal medium in a bioreactor with pH regulation at 55 °C. From time 0 to 800 hours and 1700 to 2300 hours, the concentration of cellobiose in the feed was 5 g/L . From 800 to 1700 hours, the concentration of cellobiose in the feed was 10 g/L. The red line represents the biomass concentration (as measured by OD600, using standard absorbance units). The blue line represents the n-butanol concentration in the bioreactor and the grey line represents the n-butanol concentration in the feed bottle.