FORMATION OF VALINE BY STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI.

Bragg, P. D. (University of British Columbia, Vancouver, British Columbia, Canada), and W. J. Polglase. Formation of valine by streptomycin-dependent Escherichia coli. J. Bacteriol. 88:1006-1009. 1964.-The primary extracellular products of the aerobic catabolism of glucose in streptomycin-dependent Escherichia coli were found to be carbon dioxide and acetate, the ratio of these two products being dependent on the rate of aeration but independent of antibiotic. Secondary extracellular products of dependent E. coli were valine and lactic acid; the former was produced in the presence of antibiotic under aerobic conditions, and the latter metabolite was formed under conditions of either antibiotic depletion or oxygen deprivation. The fact that the same products were formed when either streptomycin or oxygen was limiting supports the hypothesis that the antibiotic is required to complete hydrogen transport in dependent E. coli. The formation of valine appears to represent an anomalous pathway of aerobic glucose catabolism, whereby a neutral, relatively highly reduced end product is excreted.