RELATIONSHIP BETWEEN SURVIVAL, PHOTOPRODUCT PRODUCTION AND REPAIR CAPACITY IN A VARIANT OF BACILLUS CEREUS

Abstract —As sporulation progresses, there is an increased resistance to UV irradiation of the cells of Bacillus cereus var. alesti. This progressive increase is independent of post-irradiation treatment and appears to be a property of the stage of sporulation. In addition, the proportion of photoproducts formed is different for each stage of sporulation. Cells irradiated at Stage I (axial filament) of sporulation display relatively large amounts of spore photoproduct 'c' and less of photoproduct 'b'. As sporulation proceeds, UV irradiation results in the production of more spore photoproduct 'b' and less 'c', suggesting a progressive change in configuration of the DNA within the sporulating cell. If irradiated early in the process (Stage II), large amounts of cyclobutane-type dimers are also produced which, with the 'spore-specific' photoproducts, may be retained in the resultant spore. Although no excision-repair was detectable during germination of these spores, both vegetative and 'spore-specific' damage is reduced during this period. The 'spore-specific' repair mechanism may be able to remove vegetative damage from germinating spores.