“Blacklite” blue fluorescent lamp (FT15T8BLB7 15 W), placed at 30-cm distance. Revertant colonies were determined on agar prepared with semienriched medium (SEM) agar (minimum medium agar (MMA) fortified with 0.1 rng/mL of Difco nutrient broth) after 48 h of incubation at 37 “C. For dark mutagenesis, various amounts of compounds were added to molten top agar (containing 0.5 mM L-hystidine and 0.5 mM biotine, 0.1 mL of an overnight culture of Salmonella ...