Calibration of laboratory aeration apparatus.

Aeration of some sort is frequently provided during laboratory cultivation of bacteria. Since metabolic responses and the nature of fermentation products may depend upon the amount of available oxygen (Pirt, 1957), it is important to have some adequate measure of this variable. Finn (1954) has pointed out that gassing rates alone are without significance; it is necessary to determine the rate at which oxygen actually goes into solution and becomes available to the cells during growth in a given culture apparatus. Of several methods available for measuring such oxygen absorption rates (OAR), the sulfite oxidation procedure (Cooper et al., 1944) is convenient and requires little equipment. While reports have been made outlining sulfite procedures for determining oxygen absorption rates in industrial reactors (Cooper et al., 1944) and laboratory shake flasks (Corman et al., 1957), many investigators make use of small volume culture apparatus employing a constant flow air pump or a laboratory compressed air line. Although such work may involve aerating culture volumes as small as 5 or 10 ml, accurate calibration of the apparatus for OAR is still essential.