Fig. 7
Cultivation of U. cynodontis Δfuz7r Δcyp3r petefmtta pria1ria1 in a 2-L fermenter with 100 g/L initial glucose, sequentially decreasing glucose feed, in situ separation of itaconic acid by adsorption and concentration monitoring by Raman spectroscopy. Depicted are A oxygen transfer rate (OTR) and concentrations of glucose and itaconic acid, B volumetric aeration rate and filling volume, C pH, optical density (OD600), cell dry weight (CDW) and volume of titrated base solution and D respiratory quotient (line at RQ = 1) and erythritol concentration over time. Cultivation was performed at T = 30 ℃, n = 300–800 rpm, Qin = 60 SL/h, pHinitial = 5.67, pHcontrol = 3.6 (10 M NaOH), OD600,initial = 0.5 and VL,initial = 1800 mL in adapted Verduyn medium in a 2 L fermenter. DOT was controlled at 30% by adjusting stirrer speed. Glucose was fed from a 510.2 g/L solution resulting in feed rates of I: 3.4 g/h, II: 2.8 g/h, III: 2.0 g/h and IV: 1.6 g/h. Column was filled with 47 mL of Blücher 100562 activated carbon. The adsorption steps of product separation cycles were performed from 68.9 to 73.3 h, 92.2 to 95.7 h, 113.4 to 116.9 h and 136.4 to 140.4 h. For concentrations from HPLC measurements, mean values of two replicates are shown