[The role of sensitive bacteria in determining the count of phage negative colonies on solid growth media]. / Rol' chuvstvitel'nykh bakterii v opredelenii chisla negativnykh kolonii faga na plotnykh pitatel'nykh sredakh.

The purpose of the work was to study how the number of phage negative colonies on a solid growth medium depended on the concentration of a sensitive bacterial strain. For the system of phage lambda and a sensitive E. coli cell, the number of negative colonies was maximal at a concentration of ca. 4 X 10(8) cells/ml.

[Effect of factors in the cultivation of lysogenic Escherichia coli K12 (lambda) on the spontaneous level of phage]. / Vliianie nekotorykh fatorov kul'tivirovaniia lizogennykh bakterii Escherichia coli K12 (lambda) na spontannyi uroven' faga.

The content of free phage in the culture of E. coli K12 (lambda) under different conditions of their cultivation, not affecting the M-concentration of these bacteria, may differ by several times. These differences are well reproduced in consecutive experiments and little affected by the fluctuations of the absolute values of the phage titer.

[A method of estimating the effectiveness of ionizing radiation and magnetic fields for phage induction in lysogenic bacterial culture]. / O sposobe otsenki éffektivnosti deistviia ioniziruiushchikh izluchenii i magnitnykh polei na induktsiiu faga v lizogennoi kul'ture bakterii.

Either the difference delta N of the content of free phage particles in the experiment and the control or K ratio of these values can be used to estimate the effectiveness of ionizing radiation or other agents inducing phage formation in a lysogenic bacterium culture. The estimation technique the results of which are nearly independent of the fluctuations in the number of phage particles in the control, the inductor dose being invariable, is the most adequate one. The induction of phage in E. coli K12 (lambda) culture by X-rays and magnetic field is an example illustrating that the K ratio, which can be called "the induction coefficient", is in a good agreement with the requirement mentioned above. A possible nature of the phenomenon observed is discussed.