content (57% gPHB/gVSS) to be obtained directly (without a specific
enrichment step) using WAS_1 as inoculum. Furthermore, continuous
P feeding also maintained cell growth and, by increasing
catalytic biomass concentration, allowed an increase in the global
PHB mass in the reactor. At (P/C)cons of 0.5 mgP/gCODS there was
no additional XC growth but PHB production continued, indicating
that the carbon was directed to PHB storage in the biomass of PHB
producers already present. Considering a PHB content of 50% gPHB/
gVSS for the whole biomass before this limitation was applied, it is
possible that the cessation of cell growth resulted from too low an
intracellular P level due to excessive P limitation.