Radiation-sensitive and radiation-resistant mutants of Haemophilus influenzae
Journal of Bacteriology
Most of the recent investigations on the genetic control of radiation sensitivity have been done with bacteria and related bacteriophages. More specifically, the majority of these studies have included various strains of Escherichia coli (H. I. Adler, Advan. Radiation Biol. 2:167, 1966). Comparable information on other microorganisms is limited. This note relates the isolation and description of an ultraviolet (UV)-sensitive mutant and an UV-resistant mutant of Haemophilus influenzae strain Rd
... fluenzae strain Rd (H. E. Alexander and G. Leidy, J. Exptl. Med. 97:17, 1953). The resistant mutant was isolated from a logarithmic-phase culture irradiated with a dose of UV from a GE germicidal lamp (model G-30T8), permitting 0.002% survival. From the survivors, 20 colonies were inoculated into 3 % Difco Brain Heart Infusion medium, supplemented with 10 ,gg of hemin per ml and 2 jig of nicotinamide adenine dinucleotide per ml (BH medium), and grown overnight. This incubation and all other incubations were at 37 C, and liquid broth cultures were routinely shaken on a reciprocal shaker. The overnight cultures were diluted 1:50 into fresh BH medium, grown to the logarithmic phase, resuspended in saline, and UV-irradiated with a dose permitting 0.6% survival of the wildtype strain Rd. Two cultures showed survival of over 3%. Upon examination, only one of these proved to be more UV-resistant than the wild type.