The authors present the results of study of the Gibbs' free energy (--delta G) output in periodic cultures of nonpathogenic and enteropathogenic escherichia, shigellae, salmonellae, Proteus, serratia, and klebsiellae in the hydrolysate broth in a special twelve--chamber cultivator. Graphic expression--deltaG = f(N) permitted to reveal differences in the energy characteristics of individual enterobacteria genera and species. It is supposed that such studies could be useful in the choice of redox-indicators during the construction of differential-diagnostic media for the laboratory diagnosis of intestinal infections.