THE B. MYCOIDES N HOST-VIRUS SYSTEM

Abstract

Expts. were performed to determine the mechanism of release of phage from the lysogenic strain of Bacillus mycoides N. The results suggest that qualitatively the same situation obtains as in the phage-carrying cultures of B. megatherium 899 and Escherichia coli Li; i.e., the population consists of 2 kinds of cells: "lysogenes poten-tiels" and "producteurs." Quantitatively, however, there are more "producers" in a broth culture of the lysogenic B. mycoides N, at least during the first 4-8 hrs. after cells have been suspended in fresh medium, suggesting that the interaction between host and parasite is one in which the balance is easily swung in favor of the virus. These conclusions are based on the following lines of evidence: The slow "growth rate" of the lysogenic culture; the fact that the colony count falls far below the plaque count of the filament count (which correspond) for a well washed suspension; and the increase in phage output in a large number of tubes, each containing a small number of lysogenic cells, after a few hours'' incubation in nutrient broth at 30[degree]C.