BACTERIAL GROWTH WITHOUT NET PROTEIN SYNTHESIS

The report discusses postesponential growth and the so-called stationary growth phase of bacteria. Exponential growth can cease for different reasons, one of which is depletion of an essential nutrient from the medium. Depletion of different nutrients results in different patterns of postexponential growth, and different types of resting cells S. faecalis. These cell types can differ greatly in their percentage dry weight content of wall, membrane and cytoplasmic substance, and show corresponding morphological differences. The aim of the work is to understand the biochemical mechanisms which underlie these phenomena of morphological differentiation. Cystine has been the center of attention, because this amino acid plays a major role in the synthesis of both wall and membrane substance during postexponential growth. During exponential growth the organism does not depend on exogenous cystine, as long as methionine is available, because cystine can be synthesized from methionine through a well-known metabolic sequence. However, under postexponential conditions optimal production of wall and membrane substance requires a nutritional supply of both methionine and cystine. In this connection it became clear that cystine, in addition to its better known major functions source of -SH groups and -S-S bonds is also unique as an amino acid essential for the synthesis of the metabolic transfer agents, Coenzyme A and Acyl Carrier Protein ACP.