ANAEROBIC ENDOGENOUS METABOLISM IN STREPTOCOCCUS FAECALIS

Abstract

Walker , D. J. (CSIRO, University of Adelaide, Adelaide, South Australia), and W. W. Forrest . Endogenous metabolism in Streptococcus faecalis . J. Bacteriol. 87: 256–262. 1964.—Washed suspensions of Streptococcus faecalis incubated in phosphate buffer (pH 6.0) under anaerobic conditions released amino acids into the suspending medium. Little or no carbohydrate was released in soluble form, and no acid production could be detected. Cell lipid was stable, and only a small amount of nucleotide (material absorbing at 260 mμ) was released. Estimates of total carbon produced in soluble form showed that this could be almost entirely accounted for as amino acid. Over the short period during which amino acid was produced (up to 5 hr), the glycolytic activity of the cells remained fairly constant, and fell slowly thereafter to low values in 24 to 48 hr; the rate of fall depended on cell concentration. Whereas exogenous sources of energy protected against loss of glycolytic activity, arsenate, hydroxylamine, or replacement of phosphate by other buffers accelerated loss of glycolytic activity. Restoration of glycolytic activity in aged cells could be achieved by incubation with amino acids plus an energy source, with concurrent synthesis of protein but no apparent growth. Ammonium ion was not effective in protecting or restoring glycolytic activity. The nature of changes which took place during endogenous metabolism are discussed.