Shaking alone, without concurrent aeration, affects the growth characteristics of Escherichia coli

Abstract

This study investigated the effects of linear vibration on cultures grown in both hard- and soft-sided containers to determine whether vibration alone affected the growth rate. Cultures of Escherichia coli were exposed to vibrational acceleration with and without access to additional oxygen. Vibrated cultures grown in hard-sided containers exited lag phase earlier and had a higher final yield than identical unshaken cultures, whether or not the cultures had access to ambient air. Cultures grown in soft-sided containers showed no response to vibration. Vibration in hard-sided containers decreases the length of the lag phase and increases final OD in E. coli, with or without increased oxygenation. Increased mixing and improved suspension, which result from vibration of cultures in hard-sided containers, are the most likely physical mechanisms for the more favorable culture conditions. This paper demonstrates that growth enhancement of shaken cultures is a function of the rigidity of the vessel even without aeration of the medium.