title: Observations on nonconverting phage, c-n71, obtained from a nontoxigenic strain of Clostridium botulinum type C.
abstract: A nontoxigenic mutant (C-N71) obtained from a toxigenic strain of Clostridium botulinum type C, Stockholm, with nitrosoguanidine treatment was found to be lysogenic by the lysis test. Although the filtrate of a passaged lysate of this nontoxigenic but lysogenic strain, C-N71, lysed cells of the nontoxigenic strain C-AO2 equally as well as the converting phage c-st obtained from the strain C-Stockholm, it did not convert C-AO2 to the toxigenic state. The lysis spectrum of this filtrate was the same as that of the c-st phage. The ability of the filtrate to lyse the indicator cells, C-AO2, was destroyed neither by trypsin nor DNase but was inactivated by heat treatment at 80 C for 10 min. This suggested that the agent which caused lysis was not boticin but probably a phage. An electron micrograph of the complete phage, c-n71, which was similar in morphology to that of the c-st phage was obtained from the filtrate of strain C-N71. Anti-c-n71 phage rabbit serum neutralized both the lytic and the converting activities of the c-st phage. These findings strongly suggest that the c-n71 phage is a mutant of the c-st phage which lacks the gene controlling production of botulinum type C toxin.
mesh_terms: D000166:Acridines; D001435:Bacteriophages / Q000187:drug effects / Q000648:ultrastructure; D001905:Botulinum Toxins; D003014:Clostridium botulinum / Q000187:drug effects / Q000528:radiation effects; D003851:Deoxyribonucleases / Q000494:pharmacology; D006358:Hot Temperature; D008242:Lysogeny; D008937:Mitomycins; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D011831:Radiation Genetics; D014357:Trypsin / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000166:Acridines; D008937:Mitomycins; D009153:Mutagens; D009604:Nitrosoguanidines; D003851:Deoxyribonucleases; D014357:Trypsin; D001905:Botulinum Toxins