A continuous flow apparatus for the study of mixed cultures.

Although a continuous flow technique has been applied to pure culture studies by a number of workers, we are aware of only three reports (Rogers and Whittier, 1930; Savage and Florey, 1950; Zubrzycki and Spaulding, 1957) describing its use with mixed bacterial cultures. The advantages of the chemostat over the usual test tube-petri plate methods were outlined by Braun (1953) and by Novick (1955) with reference to pure cultures. Many of these advantages, we find, also apply to the study of microbial mixtures. Therefore, it is the purpose of this report to describe a modified Kubitschek (1954) chemostat which we are using to study microbial antagonism and particularly the complex interrelationships that exist among the constituents of the human fecal flora.