Fig. 4

Growth curves of C. thermocellum strains. Cells were grown on GS-2 medium or modified GS-2 medium (mGS-2) containing 2 g/L sodium sulfide and 8 g/L corn steep liquor to substitute cysteine hydrochloride and yeast extract, respectively. 5 g/L cellobiose was used as the carbon source. The optical density at 600 nm was monitored to determine the cell growth. Three independent experiments were performed for every strain to calculate the average values and standard errors