In order to better understand the mechanisms that graphics. enable Escherichia coli to survive periods of starvation and then resume growth upon addition of nutrients, different aspects of starvation and recovery have been studied. To study the regulation of the starvation-induced mcb operon, mutations in genes thought to possibly affect the activity of Pmcb were introduced into strains containing a Pmcb-lacz fusion, and []-galactosidase levels were measured and compared with wild type levels. In addition, the mcb promoter sequences required for regulation by himD were determined, and the cumulative effect of mutations in hamlet, ompR, and emrR was observed. To study the outgrowth response in E. coli, growth of wild-type and a [] strain during recovery from starvation were compared. The response of starved cells to different nutrients was measured. We have also used two-dimensional gel electrophoresis to visualize outgrowth-specific proteins. Previously, nine proteins were identified that are synthesized exclusively or predominantly during recovery from starvation, suggesting that they are somehow involved in E. coli's recovery response. One of these outgrowth-specific proteins, protein 5, was purified by ion exchange chromatography and gel electrophoresis.
