The ploidy of Vibrio cholerae is variable and is influenced by growth phase and nutrient levels

The ploidy of Vibrio cholerae was quantified under different growth conditions. The V. cholerae was found to be (mero-) oligoploid or polyploid. The ploidy levels per cell were found to be growth phase regulated. The ploidy is highest during the early stationary phase (56-72 per cell) and lowest in the long-term starved state. In addition to growth phase, an external parameter such as nutrient level influences the ploidy, i.e. ploidy reduces rapidly at the onset of the starvation. The reduction is significant with P-value < 0.05 within 2 h of starvation. Even after prolonged starvation of 10 days, the ploidy number remained above 2 per cell. Failure to obtain a monoploid V. cholerae indicates that during starvation the genome is not distributed equally to daughter cells. The activity of DNase enzyme increased during starvation that decreased the ploidy. The ploidy was restored to the pre-starvation levels with nutrient supplementation.