ANTIMUTAGENIC AND REACTIVATIVE ACTIVITIES OF DAIRY PROPIONIBACTERIA

Cells of Propionibacterium freudenreichii subsp shermanii lower the mu tagenicity of 4-nitroquinoline-1-oxide in the tester strain Salmonella typhimurium TA100 in the modified Ames test. The bacterial adaptation to the mutagen presence in the medium is demonstrated. It is possibly linked to induction of an antimutagenic activity. A dialysed fraction of soluble proteins of the extract (dialysate) lowers the mutagenicit y of UV-C light in Salmonella typhimurium and manifests protective and reactivative effects on UV-B- and UV-C-irradiated cells of S typhimur ium, Escherichia coil and the yeast Candida guilliermondii. The reacti vation does not occur after the cell irradiation with a light of total optical spectrum and visible light. (The last was studied with the ye asts.) These data serve as an indirect indication of the dialysate pro teins participation in the repair of DNA injured by UV-B and UV-C irra diation. The reactivation by dialysate occurs in E coli and the yeasts Saccharomyces cerevisiae and C guilliermondii, inactivated by heating . The reactivative activity of the dialysate was localized in its 2 su bfractions that manifests in E coli inactivated not only by UV light b ut also by heating.