The production of filterable forms of Escherichia coli in favorable and unfavorable conditions of cultivation

Summary

Three hundred seventy-sevenEscherichia coli filtrates were investigated for the presence of filterable forms. Seventeen secondary cultures were recovered from a total of 197 filtrates obtained from young 4–6 hour cultures grown on egg and egg-casein broth with aeration, i. e., in conditions favorable for growth. Sixteen filterable forms were isolated from the remaining 180 filtrates of old (30–60 day) cultures of the sameEscherichia coli strain, subjected to shaking, or double freezing and thawing, i. e., to effects destroying the bacterial cell. Thus, the supposition of some scientists, that the number of isolated secondary cultures depends on favorable growth conditions of the initial culture, was not confirmed by our investigations.