Mutation of the Methane Oxidizing Bacterium, Methylococcus capsulatus

S ummary : Spontaneous mutants of Methylococcus capsulatus resistant to antibiotics, amino acid analogues and other compounds were obtained at frequencies similar to those found in other bacteria. Attempts to increase these frequencies with the mutagens N-methyl-N'-nitro-N-nitrosoguanidine, N-nitroso-N-methyl urethane, ethyl methane-sulphonate and UV were unsuccessful. Using these mutagens, only one auxotrophic mutant was isolated from 11,082 colonies examined. The growth characteristics of this p -aminobenzoic acid requiring mutant are described.