An experimental comparison of respiration measuring techniques in fermenters and shake flasks: exhaust gas analyzer vs. RAMOS device vs. respirometer

Abstract

Respiration measurement is applied as a universal tool to determine the activity of biological systems. The measurement techniques are difficult to compare, due to the vast variety of devices and analytical procedures commonly in use. They are used in fields as different as microbiology, gene engineering, toxicology, and industrial process monitoring to observe the physiological activity of living systems in environments as diverse as fermenters, shake flasks, lakes and sewage plants. A method is introduced to determine accuracy, quantitation limit, range and precision of different respiration measurement devices. Corynebacterium glutamicum cultures were used to compare an exhaust gas analyzer (EGA), a RAMOS device (respiration measurement in shake flasks) and a respirometer. With all measuring devices it was possible to determine the general culture characteristics. The EGA and the RAMOS device produced almost identical results. The scatter of the respirometer was noticeably higher. The EGA is the technique of choice, if the reaction volume is high or a short reaction time is required. The possibility to monitor cultures simultaneously makes the RAMOS device an indispensable tool for media and strain development. If online monitoring is not compulsive, the respiration of the investigated microbial system extremely low, or the sample size small, a respirometer is recommended.

Techniques for oxygen transfer measurement in bioreactors: a review

“…A respirometer with an electro-chemical oxygen electrode can also be used to measure the OTR of a complex medium sample drawn from standard shake flasks with cotton plug, and also of medium samples drawn from a fermenter. 124 Respirometer can be used for bioreactors of any shape, however, its use is limited because of its requirement for manual handling. 124 in miniature bioreactors.…”

“…124 Respirometer can be used for bioreactors of any shape, however, its use is limited because of its requirement for manual handling. 124 in miniature bioreactors. 126 However, the dynamic gassing out method is difficult to use in mini-titreplates (MTPs) as shaking has to be stopped long before dissolved oxygen tension (DOT) measurement in order to get accurate readings.…”

“…This also compensates for the signal drift. 41,57,124 The gas concentration in the headspace of a normal flask equipped with a sterile barrier, e.g. a cotton plug, is calculated using the method of Mrotzek et al 125 The air flow rate through the measuring flask during the rinsing phase is adjusted such that the gas concentration in the headspace of the measuring flask is equivalent to that in the normal shake flask.…”

“…25% O 2 , 5% CO 2 and 70% N 2 ). 124 In a fermentor, OTR by this method is calculated by the following equation:…”

High Throughput in Biotechnology: From Shake-Flasks to Fully Instrumented Microfermentors

“…Seletzky and co-workers [74] evaluated the feasibility of this technology against other currently used devices for monitoring microbial cell growth, such as exhaust gas analyzer (EGA) and a respirometer. Although all measuring devices allowed the broad characterization of the selected culture of Corynebacerium glutamicum, data scattering with the respirometer was far higher than those of EGA and RAMOS.…”