The inhibitory action of transfer factors on lysis ofEscherichia coliK 12 by phages μ 2 and Φ 2

Abstract

A selection of fi+ resistance factors and transfer factors, when introduced into K 12F+, showed a range of inhibitory activity of lysis by the male-specific phage μ 2. This range can be used to subdivide the fi+ factors into fi+1, fi+2, fi+3 and fi+4 classes, according to the degree of inhibition of μ 2 lysis. To this subdivision can be added restriction of the ‘female-specific’ phage φ 2.Introduction of all the fi+ factors tested into K 12 HfrH totally inhibited lysis by μ 2 in spot tests, but with two fi+1 and one fi+2 factors visible lysis was obtained in agar-layer tests. These three factors caused least inhibition of transfer of pro by HfrH. It can be assumed that both tests reflect lower inhibition of sex fimbrial formation by these fi+ factors than by the remainder.The fi− factors, when introduced into K 12, can be subdivided on the basis of restrictive effects on phage φ 2.These effects can be added to phage restriction in the salmonellae for the purposes of further classification of the transfer factors and R-factors.