Ultra-violet induced mutants of blue-green algae

Summary Mutant strains of Anabaena cycadeae Reinke have been isolated after ultra-violet irradiation. All the four mutants described appear to be stable. They have been identified on the basis of their pigment composition, nutritional requirements, photoautotrophic growth and reaction to light. Strain 10 M ₁ ^L is a non-nitrogen-fixing mutant as indicated by its inability to grow on basal medium (AA) deficient in combined nitrogen. Strain 10 M ₁ ^L /10 M ₁ ^D is apochlorotic, and grows very slowly on medium AA-3 both in light and dark but comparatively better under the latter condition. Strain 10 M ₁ ^L /10 M ₂ ^D is deficient in -carotenoid, photosensitive and able to grow in dark only on AA-3 medium while strain 10 M ₁ ^L /10 M ₃ ^D is a photoheterotrophic nitrogen-fixer.