NEAR ULTRAVIOLET INDUCTION OF GROWTH DELAY STUDIED IN A MENAQUINONE‐DEFICIENT MUTANT OF <i>BACILLUS SUBTILIS</i>

Abstract

Abstract— The induction by near UV light of growth delay in Bacillus subtilis was studied utilizing a menaquinone‐deficient ( men – ) strain. Menaquinone appears to be a target molecule in this bacterial species, in view of the following: (i) the men – strain requires menaquinone precursors to terminate growth delay; (ii) the menaquinone synthesis inhibitor diphenylamine prolongs growth delay; (iii) the men – strain must be phenotypically Men* at the time of near UV irradiation to induce growth delay. These findings suggest that growth delay in B. subtilis may be associated with a prerequisite removal of photochemically altered menaquinone from the cytoplasmic membrane, rather than simply the time required for resynthesis of menaquinone. Alternatively, the altered menaquinone may inhibit some critical reaction(s) of intermediary metabolism or macromolecular synthesis.