Differential production of acid by Enterobacteriaceae in OF media and in fermentation broth.

Several species of Enterobacteriaceae were checked for acid formation from some carbohydrates or alcohols in OF medium [OF Basal Medium, Baltimore Biological Laboratories] and in a traditional "fermentation broth". After selection of those species that formed acid only oxidatively or fermentatively in OF, it was found that acid formation in the fermentation broth could reflect fermentation or oxidation, but that it was not necessarily related to either. In oxidative species, it occurred less frequently than oxidation in OF and was usually delayed. Fermentative species (in OF) either yielded acid in fermentation broth or did not, depending on the species. Thus, OF media cannot be substituted for traditional broths, although they may be of value in differentiating certain species.