pH difference across membrane under different growth conditions

Range 0.18-0.3 Unitless
Organism Bacteria Escherichia coli
Reference Tran QH, Unden G. Changes in the proton potential and the cellular energetics of Escherichia coli during growth by aerobic and anaerobic respiration or by fermentation. Eur J Biochem. 1998 Jan 15251(1-2):538-43. Table 2PubMed ID9492330
Method Growth was performed in supplemented M9 medium with glycerol and electron transfer acceptors as described in ref. pH difference was determined by silicone oil centrifugation, and radiolabelled benzoate was mixed with cell suspensions. From the distribution of benzoate, Delta pH = log[benzoate(in)]/[benzoate(ex)] was calculated (in, internal ex, external)
Comments High value (0.3 pH units) for growth on (Glycerol + O2) substrate, corresponds to a -20 mV difference of electric potential (of Benzoate ion). Low value (0.18 pH units) for fermentative growth on Glucose corresponds to a -12mV difference of electric potential (of Benzoate ion). pH electric potential difference calculated from: pH potential difference=2.3×(RT/F)×?pH. R-gas constant,F-Faraday constant, T-temperature Kelvin (336 degrees), range of ?pH=0.18-0.3.
Entered by Uri M
ID 103387