Online and non-invasive measurement of biomass in shake flask: concept and application

Shake flask cultivation is still one of the most widespread cultivation method for screening processes and small scale protein production. Nevertheless online monitoring for shake flask cultivation was considerably neglected up to the last years where pH and pO₂ sensorspots started to integrate in the single use technology. The presented new system was successfully implemented in the shaker platform. In the context of this work a new multisensory platform with an additional biomass sensor  was applied to protein production processes using E. coli K12. In addition to biomass cultivations could be monitored by measurement of basic cultivation parameters pH and O2. The biomass sensor is based on light backscattering of cells through the transparent flask wall at a dominance wavelength of 625 nm. The fully non-invasive measurement can be performed at a high measuring frequency of up to 10 s. The sensor signal can be user-calibrated against standard measurements like CDW or OD_600. With the given calibration it can be used e. g. in order to determine the precise and adequate moment of induction.