Determination of CO₂ sensitivity of micro-organisms in shaken bioreactors. I. Novel method based on the resistance of sterile closure.

Influence of carbon dioxide on growth and product kinetics of industrially important micro-organisms is essential for the interpretation of a bioprocess. In this research, the CO₂ effects on productivity and growth rate of micro-organisms have been studied by using a variety of kplug. The applied method is based on a different concentration of CO₂ in the headspace of ventilation flasks. The presented method is simple, inexpensive and shows similar results compared to large-scale fermentation regarding the evolution of CO₂ in a batch system. For the investigation of the proposed method, experiments employing Arxula adeninivorans LS3, Corynebacterium glutamicum (DM1730 and ATCC WT13032) and Hansenula polymorpha DSM70277 as model organisms in the ventilation flasks are performed. The fermentations in the RAMOS (respiratory activity monitoring system) device were carried out with a normal aeration rate (1 vvm) and under the same operating conditions as the ventilation flask f1. The modified unsteady-state model was used to predict the operation conditions of a biological system in the ventilation flasks. In the present study, a novel and easy method for the quantification of CO₂ sensitivity of micro-organisms in shaken bioreactors (called ventilation flask) was achieved.