Figure 4.
Substrate specificity and substrate ratio for butanol production. (A) Impact of electron donor on butanol yield. Engineered E. coli MG1655 (pQE-adhE2/ptb/buk) strain was grown under anaerobic condition and resuspended in Terrific Broth with 40 mM butyric acid and 40 mM of either glucose or glycerol as electron donor. Various substrates consumed and butanol produced were analyzed through HPLC after 120 h of incubation. The butanol yield was calculated with respect to (wrt) each carbon source. (B) Different ratios of glycerol and butyric acid were tested for production of butanol using cells at the OD600 of 1.0. (C) Different butyric acid concentrations were tested for production of butanol using cells at the OD600 of 10 by keeping the glycerol to butyric acid ratio fixed at 1.5:1.