RT Journal Article SR Electronic(1) A1 Eberl, Leo A1 Givskov, Michael A1 Sternberg, Claus A1 Møller, Søren A1 Christiansen, Gunna A1 Molin, SørenYR 1996 T1 Physiological responses of Pseudomonas putida KT2442 to phosphate starvation JF Microbiology, VO 142 IS 1 SP 155 OP 163 DO https://doi.org/10.1099/13500872-142-1-155 PB Microbiology Society, SN 1465-2080, AB The physiological responses of Pseudomonas putida KT2442 to phosphate starvation were examined with respect to cell morphology, qualitative demonstration of the accumulation of the intracellular storage component poly-3-hydroxyalkanoate (PHA), cellular ATP and ribosome content, and the rate of total protein synthesis. Upon prolonged incubation under phosphate-limiting conditions, the number of viable cells decreased by two to three orders of magnitude during the first 3 weeks. However, after this decline, viability of the cultures remained remarkably constant for many weeks. The cells remained rod-shaped under phosphate starvation conditions with a tendency to swell in parallel with the accumulation of PHA. Protein synthesis and ribosome concentration were gradually reduced, and ATP levels dropped to very low values after the onset of starvation; later, however, there was a return to near-normal ATP concentrations. Evidence was obtained that the strong selective pressure imposed by phosphate deprivation forces the selection of mutants with a competitive advantage. These mutants are able to grow, possibly utilizing nutrients derived from dead cells, and eventually take over the cultures. One frequently encountered mutant formed smaller colonies on rich solidified medium and displayed an altered cell morphology. This mutant was isolated and further characterized. By employing a bioluminescence-based marker system, we demonstrated that this mutant is able to replace wild-type cells in mixed culture experiments. Thus, long-term phosphate-deprived cultures represent dynamic regimes that can undergo population shifts., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-142-1-155