Combined dissolved oxygen tension and online viscosity measurements in shake flask cultivations via infrared fluorescent oxygen‐sensitive nanoparticles

Abstract

Oxygen supply is one of the most critical process parameters in aerobic cultivations.To assure sufficient oxygen supply, shake flasks are usually used in combination with orbital shaking machines. In this study, a measurement technique for the dissolved oxygen tension (DOT) in shake flask cultures with viscosity changes is presented. The movement of the shaker table is monitored by means of a Hall effect sensor. For DOT measurements, infrared fluorescent oxygen-sensitive nanoparticles are added to the culture broth. The position of the rotating bulk liquid needs to be determined to assure measurements inside the liquid. The leading edge of the bulk liquid is detected based on the fluorescence signal intensity of the oxygen-sensitive nanoparticles. Furthermore, online information about the viscosity of the culture broth is acquired due to the detection of the position of the leading edge of the bulk liquid relative to the direction of the centrifugal force, as described by Sieben et al. (2019. Sci. Rep., 9, 8335). The DOT measurement is combined with a respiration activity monitoring system which allows for the determination of the oxygen transfer rate (OTR) in eight parallel shake flasks. Based on DOT and OTR, the volumetric oxygen transfer coefficient (k L a) is calculated during cultivation. The new system was successfully applied in cultivations of Escherichia coli, Bacillus licheniformis, and Xanthomonas campestris. K E Y W O R D S dissolved oxygen tension, optical measurement, oxygen-sensitive nanoparticles, RAMOS, shake flask, viscosity

Implementation of Perforated Concentric Ring Walls Considerably Improves Gas-Liquid Mass Transfer of Shaken Bioreactors

“…A more quantitative confirmation by directly measuring the DOT levels during the cultivation was not done as the focus of this study is on the improvement of the gas-liquid mass transfer by the newly proposed flask design. A deeper quantitative characterization with respect to the DOT levels would need a carefully designed experimental set-up, e.g., by using oxygen-sensitive nanoparticles ( Ladner et al, 2019 ) as conventional approaches to measure DOT in shake flasks can lead to erroneous results ( Hansen et al, 2011 ). However, it could clearly be demonstrated that with the newly proposed perforated ring flasks design non-oxygen limited conditions at the OTR levels usually only seen in stirred tank bioreactors can be achieved in shaken bioreactors.…”

Factors involved in heterologous expression of proteins in E. coli host

“…Researchers use shake flasks for the optimization of growth conditions. These shake flasks do not require any special instruments (Ladner et al 2019 ). However, unlike bioreactors, standard cultivation of E. coli in shake flasks is done in batches.…”

Pasteurellosis Vaccine Commercialization: Physiochemical Factors for Optimum Production

“…Shake Flasks Shake flask fermentations are normally carried out in a laboratory and are widely used to investigate microbial culture behavior on a small scale, mainly to explore feasibility [55]. In bioprocess development applications, the flasks are mainly used for screening and early bioprocess development, which, in medium-level optimization and the preparation of starter cultures in shake flasks, are applied as a pre-culture of stirred-tank fermentation [56]. In addition, the shake flask system enables the performance of a high number of cost-efficient parallel fermentation procedures on a small scale within a set of optimum fermentation conditions [55,57].…”