[Effect of reduced concentrations of carbon, nitrogen, and phosphorus in a medium on growth of three dissociants of Pseudomonas aeruginosa].

The effect of lowered concentrations of carbon, nitrogen, and phosphorus sources in the medium on the specific growth rate mu of the R, S, and M dissociants of the hydrocarbon-oxidizing strain Pseudomonas aeruginosa K-2, culture pH, and the population composition was studied. Within the first 16 hours of cultivation in all of the four media tested, the R, S, and M dissociants had virtually identical mu. The maximal values of mu were reached by the 20th h of growth in the basal medium (R and S dissociants) and in the carbon-deficient medium containing 0.4% glucose (M dissociant). The R and M dissociants showed the most rapid decrease in mu in the nitrogen-deficient medium containing 0.55% NaNO3. By the end of cultivation in the basal medium, the pH of the R, S, and M cultures decreased to 6.3, 5.3, and 3.3, respectively. In the case of the carbon-deficient medium, the drop in the culture pH was lower. After a 2.5-day incubation of the S dissociant in the phosphorus-deficient medium containing 0.028% NaH2PO4.2H2O and of the M dissociant in the basal medium supplemented with chalk powder, these dissociants were completely displaced from the media.