Lysogeny in Providence Strains and the Host-range of Providence Bacteriophages

Abstract

BIOCHEMICALLY Providence strains are closely related to Proteus organisms, especially P. rettgeri, and on these grounds the name Proteus inconstans has been suggested for them¹. The guanidine + cytosine content of Providence strains is very similar to those of P. hauseri and P. rettgeri², and recently it was found that many Proteus (especially rettgeri) phages productively lyse Providence strains³. It was decided to investigate the reciprocal relationships, that is, to test phages primarily isolated on Providence strains for action on Proteus organisms. Media used were those previously used⁴. Thirty-seven Providence cultures comprising 25 different serological groups were used. They are all National Collection of Type Culture strains and were kindly supplied by Miss Shona Wright of the Department of Bacteriology, University of Edinburgh. In addition, 25 P. rettgeri cultures (17 locally isolated, 8 N.C.T.C. strains) 17 P. morgani cultures (11 locally isolated, 8 N.C.T.C. strains) and 31 P. hauseri strains previously described5 were used in host-range experiments. The rettgeri strains can all be differentiated on the basis of susceptibility to a series of P. rettgeri phages. The hauseri strains were in the A morphological phase and all showed a positive Dienes phenomenon when matched against one another⁶.