[Serologic properties of mutants of Rhizobium trifolii and their interrelationship with effectiveness]. / Serologicheskie svoistva mutantov Rhizobium trifolii i vzaimosviaz' ikh s éffektivnost'iu.

UV and gamma irradiation of Rhizobium trifolii, strains 347a and 311a, produced their mutants with changed antigenic properties and effectiveness. The extent of changes of antigens did not depend on the dose of irradiation because mutants that completely lost antigens typical of the parent strains were obtained at different doses of UV and gamma rays. No correlation was established between the antigenic properties of the mutants of Rhizobium trifolii and their effectiveness.

[Effect of ultraviolet rays on the activity of clover nodule bacteria]. / Vliianie ul'trafioletovykh luchei na aktivnost' kluben'kovykh bakterii klevera

The effect of UV on the survival, morphological variability, and effectiveness was studied with nodule bacteria of clover, strain 374a. The survival of the strain directly depended on the dose of UV rays, being 43.3% at 130 erg/mm2 and 0.000022% at 22,900 erg/mm2. UV irradiation yielded two morphological types of colonies; they differed by the production of slime which was less at higher doses of UV (15,970 to 22,900 erg/mm2). Variants with either positive or negative effectiveness were obtained by the action of UV. The positive variants increased the crop of clover by 21-60%, as compared with the parent strain 347a, while the negative variants decreased it by 18.3-35%.