Responses to nutrient starvation in Pseudomonas Putida KT2442: analysis of general cross-protection, cell shape, and macromolecular content

The physiology of Pseudomonas putida KT2442 with respect to growth and carbon starvation was studied. During the transition from growth to nongrowth, the cell shape changes from cylindrical to spheric, a change which is accompanied by reductions in cell size, DNA and ribosome content, and the rate of total protein synthesis. In addition, a pattern of general cross-protection develops, which enables the cells to survive environmental stresses such as high and low temperatures, elevated osmolarity, solvents, and oxidative agents. Cultures are almost fully viable during 1 month of carbon, nitrogen, and multiple-nutrient starvation and are considered to be in an active nondormant state. In contrast, strain KT2442 does not survive well under conditions of sulfate and phosphate starvation. In nature, most bacteria are challenged by conditions of widely changing nutrient availability as well as by exposure to various forms of physical stress. Bacteria of the Pseudomonas spp. are found in soil, fresh water, sediments, and seawater and are known plant and root colonizers. Especially in the rhizo-sphere, the nutrient-rich conditions surrounding a growing root stimulate bacterial growth (32). However, in bulk soil a