Cotton Closure as an Aeration Barrier in Shaken Flask Fermentations

摘要

Oxygen transfer through a cotton plug follows Fick's law of diffusion. The apparent diffusion constant decreases as the density of cotton packing is increased. Formulas are derived which relate oxygen transfer to cotton-plug dimensions. Calculations indicate that the dimensions of a cotton plug can affect both the maximal oxygen uptake rate and the gas composition inside a shaken flask. In some situations, as with large flasks, the cotton closure can become the limiting factor to aeration.