Effects of Starvation on the Protein of Escherichia coli

A large volume of work has been published on the synthesis and degradation of proteins. The bacterium Escherichia coli has been used extensively in this type of investigation. E. coli when placed in a medium containing a nutrient has three phases of growth. The first phase, called the logarithmic phase, is one of rapid growth. After the nutrient has been utilized, the bacteria exist in a non-growing state for a period of time until they enter the death phase, when they die as rapidly as they grew in the logarithmic phase of growth. Although different methods have been used, the same conclusions have been reached in regard to protein degradation. Cowie, incorporating radioactive sulfur into the proteins, recorded .5% of the total bacterial protein being degraded per hour. Mandelstam, using a radioactive solution of an amino acid, leucine, noted that specific radioactivity of the medium had not changed appreciably after a period of time. He concluded from this, there was little or no protein degradation in rapidly growing cultures. Fox and Brown record slightly higher values for protein degradation in the rapid phase of growth. The general conclusion one derives from the literature is that little or no protein degradation occurs during the logarithmic phase of growth in E. coli