[Variability in the amylolytic thermophilic bacterium, Bacillus diastaticus, induced by ultraviolet rays]

The UV-induced variability of the amylolytic thermophilic Bacillus diastaticus 13 was studied. The biosynthesis of amylase was found to very under the action of UV from 2.2 to 158.7% A "plus" variant referred to as the mutant UV 1 was produced at a dose of UV equal to 41.8-10(2) erg/mm2. Its further selection without using a mutagen made it possible to select a variant UV 1-25 which surpassed the parent strain by 43.3% in amylase biosynthesis. UV-irradiation produced also two mutants with a low activity in amylase biosynthesis. The requirement of growth factors was studied with several mutants.