Development of a bellows pumping device for enhancing ventilation to shake-flask systems

Abstract

Shake-flask culture has been developed as an alternative to microbial surface culture. Shake-flask systems are known to affect microbial activity via composition of the headspace and ventilation ability of the culture plug. Gaseous control methods are limited to improvement of monitoring devices for shake-flask. In this study, a novel device was developed to improve ventilation in shake-flask culture without any complicated operations. This device was designed to induce a reciprocating motion of metal balls that results in the activation of the built-in bellows pump to send the outside air forcibly and aseptically into the flask gas phase. The ventilation capacity of the developed nonelectric bellows pump for shake-flask (NeBP-sf) was evaluated using the half-life of CO2 as an index. The maximum CO2 half-life of the NeBP-sf was found to be less than 10 min, and more than 5 times higher than that of the control (about 50 min). The NeBP-sf improved the ventilation capacity of shaking culture, resulting in enhanced growth of Escherichia coli compared with the control. Overall, these findings show that the developed device could have practical applications in reducing the space requirements and does not require additional electrical power to function.