Fig. 9

Absolute accumulated glucose consumption and glucose release rates based on oxygen transfer rates. (A) Absolute accumulated glucose consumption for E. coli and H. polymorpha fed-batch cultivations. Glucose consumption was calculated with Eqs. (3)-(5) based on the oxygen consumption (Figure S11). Only every fifth point is shown for clarity. (B) Based on the absolute accumulated glucose consumption (Fig. 9A), the glucose release rates were determined for the fed-batch phase for the time frame, that is marked in Fig. 9A as the light green area between the two vertical, dotted lines. The slope of the linear fit within this time frame equals the glucose release rate. Mean values were calculated for cultivations with one polymer ring (Z_height = 3 mm) in three different positions (H_position = 0 mm, 1.5 and 3.5 mm) with the same filling volume (V_L = 0.8 mL and 1.2 mL) and initial optical density (OD_{600 nm, start} = 0.5 and 1.0). The horizontal grey dashed and dotted line marks the mean value of results from E. coli cultivations, while the horizontal grey dashed line marks the mean value from results from H. polymorpha cultivations. The coloured area depicts the respective standard deviation. Polymer rings: polymer rings with black dye and glucose crystals, d_inner = 8 mm, Z_height = 3 mm, H_position = 0 mm, 1.5 and 3.5 mm. Experimental parameters: initial pH = 7.5 (E. coli) and 6.0 (H. polymorpha), V_L = 0.8 mL and 1.2 mL, T = 37 °C (E. coli) and 30 °C (H. polymorpha), n = 1000 rpm, d₀ = 3 mm, OD_{600 nm, start} = 0.5 and 1.0