AUTORADIOGRAPHIC DETECTION OF RADIOACTIVE BACTERIA INTRODUCED INTO SEA WATER AND SEWAGE

An autoradiographic method to trace the dissemination in water of radioactive bacteria is reported. It has been tested for accuracy and sensitivity and a field trial has been performed. The method appears suitable for practical use and permits the study of environmental effects on the spreading bacteria.

NEW TYPE OF SEX FACTOR-SPECIFIC BACTERIOPHAGE OF ESCHERICHIA COLI

Watanabe, Tsutomu (Keio University, Tokyo, Japan), and Motoyuki Okada. New type of sex factor-specific bacteriophage of Escherichia coli. J. Bacteriol. 87:727-736. 1964.-A virulent phage, W-31, isolated from sewage water, was found to have a specific relationship to the sex factor of Escherichia coli K-12; this phage formed large, clear plaques on F(-) and stable Hfr strains but small, turbid plaques on F(+) strains. Unstable Hfr strains gave intermediate-type responses to phage W-31. Further, adsorption and nucleic acid injection of phage W-31 occurred equally in F(-) and F(+) strains. In addition, a majority of F(+) cells were killed by infection with phage W-31 without producing progeny phage. These results suggest that some step(s) after nucleic acid injection is suppressed by an autonomous F but not by an integrated F. Colicinogenic factor B was also found to suppress the production of progeny of phage W-31, although colicinogenic factor E(2), prophage lambda, and R factors did not show such inhibitory effects against this phage. Colicinogenic factor B in an F(-) strain derived from an Hfr strain did not suppress the multiplication of phage W-31; this strain was further found to carry out chromosome transfer in the same order as the original Hfr strain.