Spontaneous mutation and recombination among brucellaphages.

Merz, George S. (University of Wisconsin, Madison), and Joe B. Wilson. Spontaneous mutation and recombination among brucellaphages. J. Bacteriol. 91:2356-2361. 1966.-Two plaque morphology variants, as seen on Brucella abortus 544A, termed c (for clear plaque) and lc (for late-clearing plaque) were isolated from stocks of wild-type brucellaphage and from colonies of B. abortus 544A which had undergone an alteration in colonial morphology associated with the establishment of the phage carrier state. Single-burst experiments showed that the phage variants arise by spontaneous mutation of the wild-type phage during its replication on B. abortus strain R19. Two-factor crosses of independently occurring c mutant phages showed the presence of wild-type recombinants among the progeny. Control experiments showed that there are no strong selective forces against either wild-type or c mutant phage inherent in the cross-procedure. Other control experiments ruled out the possibility that wild-type phage in the cross-progeny resulted from either back mutation of the c mutants or the presence of wild-type phage among the input c mutants.