Ultraviolet sensitivity and photoproducts in spore-like bodies of an excision-repair-deficient and dipicolinic-acid-less strain of Bacillus subtilis.

Bacillus subtilis strain UVS-42DPA is defective in both excision-repair capability and dipicolonic acid(DPA)accumulation. In sporulation medium, it forms spore-like bodies, which are sensitive to ultraviolet light (UV) as the vegetative cells and produce mostly cyclobutane dimers instead of "spore photoproduct" upon UV irradiation. The results suggest that the drastic change in the photochemical reactivity of DNA during sporulation might be induced and(or) maintained by the accumulation of DPA.