An efficient mutational method for photosynthetic bacteria

The pigment and auxotrophic mutants of Rhodobacter sphaeroides Y6 were obtained by treatment with ethyl methanesulfonate (EMS) followed by lithium chloride (LiCl). Treatment with 0.081 MEMS and subsequent treatment with 0.071 M LiCl resulted in 12% higher frequency og than that by 0.081 mol/L EMS alone, and the same frequency of pigment mutations than application of 0.081 M EMS alone; the frequency of auxotrophic mutations increased 2.5-fold when treatment with lithium chloride was applied. A blue shift by 10 nm was recorded in the absorption spectrum of carotenoids form YM5-3 green mutant; considerable accumulation of neurosporine was revealed by HPLC and mass spectrometry. The method is efficient for isolating the mutants of photosynthetic bacteria. Published in Russian in Mikrobiologiya, 2006, Vol. 75, No. 6, pp. 758–764. The text was submitted by the authors in English.