According to the origin of the sludge, the microbial communities
could be differently affected by the strong P limitations applied and,
according to the microbial population, the impact of such P limitation
on the PHA storage response could also be different. In the present
study, for the same (P/C)app PHA production by WAS_2 occurred
for 90 h (throughout the culture) whereas for WAS_3 culture, PHB
was no longer produced after t = 30 h. Population dynamics could
explain this phenomenon. To test this hypothesis, molecular analysis
of the microbial population was performed.