FIG. 1.

Growth and PHA content of P. oleovorans in chemostat culture at different dilution rates, as a function of the carbon-to-nitrogen ratio of the medium feed (C₀/N₀, in moles per moles) with octanoate as the sole source of carbon and energy and ammonium as the only source of nitrogen. The concentrations of nitrogen and all other inorganic nutrients in the feed were kept constant (N₀ = 10.7 mM), whereas the concentration of octanoate was varied. The zone of dual-nutrient-limited growth (shaded) was calculated from the slopes of residual nitrogen (lower boundary) and octanoate (upper boundary). The upper boundary at a D of 0.05 h⁻¹ could not be determined due to by-product formation and unstable growth (see the text).