Medial and Mutagen Controlled Specificity of Dark Repair in Escherichia Coli B/R

We have studied the contribution of medial supplementation (supplementation with traces of the required amino acid and enrichment with nutrient broth) on the repair of suppressor mutations following treatments with ultra violet light (UV) and nitrosomethyl urea (NMU) in E. coli B/r. It has been shown that broth enrichment preferentially affects the suppressor mutations. It has been shown further that, on broth free plates, the proportion of suppressors increases with increase in UV dose and that this may be brought about through inhibition by UV of the same repair system interfered with by broth. With. NMU, on the other hand, the proportion of suppressors are not different for mutations scored on plates supplemented with small amounts of the required amino acid and those scored on broth enriched media.