Analysis and effect of conventional flasks in shaking culture of Escherichia coli

Masato Takahashi,Hideki Aoyagi

doi:10.1186/s13568-020-01013-7

Abstract

The circulation direct monitoring and sampling system (CDMSS) is used as a monitoring device for CO2 and O2 concentrations of bypass type in shake-culture flask. The CDMSS could measure kLa, an index for evaluating the performance of aerobic culture incubators, and kG, an indicator of the degree of CO2 ventilation in the flask gas phase. We observed that cylindrical flasks provided a different culture environment, yielded a much higher kG than the Erlenmeyer and Sakaguchi flasks, and yielded kLa equivalent to that by Erlenmeyer flask by setting the ring-type baffle appropriately. Baffled cylindrical flask used for Escherichia coli K12 IFO3301 shake culture maintained lower CO2 concentrations in the headspace than conventional flasks; therefore, CO2 accumulation in the culture broth could be suppressed. Cell growth in baffled cylindrical flask (with kLa equivalent to that of the Erlenmeyer flask) was about 1.3 and 1.4 times that in the Erlenmeyer and Sakaguchi flasks, respectively. This study focused on the batch culture at the flask scale and designed the headspace environment with low CO2 accumulation. Therefore, we conclude that redesign of flasks based on kLa and kG may contribute to a wide range of fields employing microorganism culture.

Highlights

In 1932, shake-flask culture was developed for submerged culture of fungi to overcome the biomass yield limitations of surface culture (Kluyver et al 1933)
Our study examined the behaviour of Escherichia coli K12 IFO3301 shake culture in various flasks by using circulation direct monitoring and sampling system (CDMSS)
At the first, we compared typical shake flask cultures of E. coli K12 IFO3301 performed with Erlenmeyer and Sakaguchi flasks

Summary

Introduction

In 1932, shake-flask culture was developed for submerged culture of fungi to overcome the biomass yield limitations of surface culture (Kluyver et al 1933). Shake-flask culture is frequently used to screen secondary metabolites and to optimise culture conditions for microorganisms in the initial steps of bioprocess development. Gaseous monitoring devices are remarkable because accurate measurement with conventional sampling methods, which include the interruption of shake culture and the transporting to a clean bench, the opening of culture plug at clean bench, are difficult to achieve due to Henry’s law (Takahashi et al 2017; Takahashi and Aoyagi 2018a). The methods of monitoring gas concentration in shake-flask culture are characterised by the measuring site, the principle of measurement equipment, and the measurement style (Takahashi and Aoyagi 2018b). To the best of our knowledge, the Circulation Direct Monitoring and Sampling System (CDMSS) is the first bypass device to be developed that can monitor the behaviour of C O2 and O2 in the gas–liquid phases and obtain a sample without interrupting the shaking of the culture

Methods

Results

Conclusion