Fig. 2
Comparison of DOT measurements via oxygen-sensitive nanoparticles and sensor spot (optode) during K. lactis GG799 pKlac1 cultivation. a Simultaneous online monitoring of the oxygen transfer rate (OTR) measured with a RAMOS device and the dissolved oxygen tension (DOT) measured via dispersed oxygen-sensitive nanoparticles and sensor spot in the same RAMOS shake flask. b Respiratory quotient. c Calculation (Eq. 1) and error estimation (Eq. 2) of the kLa values during RAMOS aeration phases. The total error is represented by the surrounding area, while the fraction of each error component is indicated by a different color as explained in the text. For comparison, the kLa value at the beginning (kLaMeier,start = 221 h−1) and the end of the cultivation (kLaMeier,end = 243 h−1) estimated according to the correlation of Meier et al. [34] are shown by the solid and dashed (±27 h−1) dark blue lines. The measured osmolality for the calculation of kLaMeier is shown in orange. Cultivation conditions: Complex YEP medium with 40 g L−1 glucose and 0.1 g L−1 oxygen-sensitive nanoparticles, 250 mL RAMOS shake flask, 30 °C, n = 200 rpm, VL = 10 mL, shaking diameter d0 = 50 mm