Scale‐up from shake flasks to fermenters in batch and continuous mode with Corynebacterium glutamicum on lactic acid based on oxygen transfer and pH

Abstract

Scale-up from shake flasks to fermenters has been hampered by the lack of knowledge concerning the influence of operating conditions on mass transfer, hydromechanics, and power input. However, in recent years the properties of shake flasks have been described with empirical models. A practical scale-up strategy for everyday use is introduced for the scale-up of aerobic cultures from shake flasks to fermenters in batch and continuous mode. The strategy is based on empirical correlations of the volumetric mass transfer coefficient (k(L) a) and the pH. The accuracy of the empirical k(L) a correlations and the assumptions required to use these correlations for an arbitrary biological medium are discussed. To determine the optimal pH of the culture medium a simple laboratory method based on titration curves of the medium and a mechanistic pH model, which is solely based on the medium composition, is applied. The effectiveness of the scale-up strategy is demonstrated by comparing the behavior of Corynebacterium glutamicum on lactic acid in shake flasks and fermenters in batch and continuous mode. The maximum growth rate (micro(max) = 0.32 h(-1)) and the oxygen substrate coefficient (Y O2 /S= 0.0174 mol/l) of C. glutamicum on lactic acid were equal for shake flask, fermenter, batch, and continuous cultures. The biomass substrate yield was independent of the scale, but was lower in batch cultures (Y(X/S) = 0.36 g/g) than in continuous cultures (Y(X/S) = 0.45 g/g). The experimental data (biomass, respiration, pH) could be described with a simple biological model combined with a mechanistic pH model.

Impact of gas–liquid mass transfer on organic acids production by Corynebacterium glutamicum in unbaffled shake flasks

“…Furthermore, Seletzky et al (2007) demonstrated that, in a medium designed for C. glutamicum cultures, the value of the k L a in fresh culture medium could be assumed equal to the k L a value in water, as far as liquid viscosity remained unchanged [13].…”

“…This coefficient has been measured in shake flasks using conventional systems equipped with sensor spots for online dissolved oxygen monitoring or using the sulfites reaction method [21], [26][27][28]. Moreover, mathematical models and empirical correlations have also been used for gas-liquid mass transfer coefficient modeling [13,24], [29][30]. However, no literature data linking organic acids production by C. glutamicum and oxygen transfer in shake flasks could be found.…”

“…For strict aerobic microorganisms, oxygen limitation and / or anaerobiosis may result in drastic effects on cell physiology and fermentation kinetics, similarly to nutrient limitation. When oxygen becomes limiting in the culture broth, microorganisms may respond by modifying their internal metabolism [13][14]. In general, the central metabolism is known to display important differences under fully aerobic and oxygen-limited conditions.…”

Evidence for a Key Role of Cytochrome bo3 Oxidase in Respiratory Energy Metabolism of Gluconobacter oxydans

“…Commercial versions of RAMOS are available from Kuhner (Birsfelden, Switzerland) or Hitech Zang (Herzogenrath, Germany). This device has already been intensively in other investigations to study and characterize microbial systems (30)(31)(32). Offline sampling was conducted with the help of parallel 250-ml unbaffled shake flasks running simultaneously under identical conditions (30°C; 50-mm shake diameter) as the RAMOS cultivations in a ISF-4-W Kuhner shaker (Birsfelden, Switzerland).…”

Novel dynamic model for aerated shaking bioreactors

“…To this end, significant attention needs to be paid to provide scientists with detailed and precise models to gain sufficient understanding about behavior of the dynamic systems [11]. In addition, mathematical models are important for computational simulations, provided that the accuracy and limitations of the model are considered [12], [13].…”