If an enriched biomass is supplied with all essential nutrients for active growth during a PHA accumulation process, then eventually PHA storage activity offers no ecological advantage and even non-PHA storing bacteria will be expected to begin to proliferate. Due to the feed-on-demand accumulation strategy applied for the present investigation, carbon supply repeatedly approached limitation and the COD supply rates were constrained so that an excess of carbon was never sustained in the mixed liquor for extended periods of time. Many relatively small respiration-triggered aliquot additions of feedstock, with peak COD concentrations of about 200 mg/L, maintained a near maximal respiration activity of the biomass. Pulse feedstock additions were made in close timing to substrate utilization in order to sustain respiration conditions that have been experienced to influence PHA-in-biomass molecular weight (Werker et al., 2013). The feeding approach of the present investigation is in contrast to most other studies on the subject of evaluating the influence of nutrients in MMC PHA accumulations, including for example