[Efficacy of biological preparations of soybean root nodule bacteria modified with a homologous lectin].

The effect of various biopreparations of the root nodule bacterium Bradyrhizobium japonicum, modified with a homologous lectin, on the virulence of Rhizobia, the nitrogen-fixing activity of root nodules, and the productivity of the soybean (Glycine max (L.) Merr.) was studied. It was shown that a homologous lectin, added to a bacterial suspension when manufacturing biopreparations on a liquid and solid support, increases the efficiency of the soybean symbiotic system and the productivity of the host plant. The potentialities of using bacterial preparations modified with a homologous lectin are discussed.

[The significance of exometabolites in the formation and operation of the soybean-rhizobium symbiosis]. / Rol' ékzometabolitov v protsesse formirovaniia i funktsionirovaniia soevo-rizobial'nogo simbioza.

The effect of various inoculates of the soybean-specific strain of nodule bacteria Bradyrhizobium japonicum 634b (unwashed cells, cells washed from the exopolysaccharide-protein complex, and cells combined with the complex) on the formation and operation of soybean-rhizobium symbiosis. It was shown that addition of the exopolysaccharide-protein complex doubled the ability of the microsymbiont to form nodules, nodule weight, and the nitrogenase activity of the nodules. Bradyrhizobium japonicum 634b cells washed from exometabolites had lower indices of symbiotic activity than their intact counterparts.

[The biological activity of the Sinorhizobium meliloti glucan]. / Biologicheskaia aktivnost' gliukana Sinorhizobium meliloti.

The study of the effect of the periplasmic glucan isolated from the root-nodule bacterium S. meliloti CXM1-188 on the symbiosis of another strain (441) of the same root-nodule bacterium with alfalfa plants showed that this effect depends on the treatment procedure. The pretreatment of alfalfa seedlings with the glucan followed by their bacterization with S. meliloti 441 insignificantly influenced the nodulation parameters of symbiosis (the number of root nodules and their nitrogen-fixing activity) but induced a statistically significant increase in the efficiency of symbiosis (expressed as the masses of the alfalfa overground parts and roots). At the same time, the pretreatment of S. meliloti 441 cells with the glucan brought about a considerable decrease in the nodulation parameters of symbiosis (the number of the root nodules and their nitrogen-fixing activity decreased by 2.5-11 and 7 times, respectively). These data suggest that the stimulating effect of rhizobia on host plants may be due not only to symbiotrophic nitrogen fixation but also to other factors. Depending on the experimental conditions, the treatment of alfalfa plants with the glucan and their bacterization with rhizobial cells enhanced the activity of peroxidase in the alfalfa roots and leaves by 10-39 and 12-27%, respectively.

[Formation and function of the bean-rhizobium symbiosis in soy plants upon introduction of strains of Azotobacter and Bacillus species]. / Formirovanie i funktsionirovanie bobovo-rizobial'nogo simbioza u rastenii soi pri introduktsii shtammov rodov Azotobacter i Bacillus.

The effects of bacteria belonging to the genera Azotobacter and Bacillus in a mixed culture with Bradyrhizobium japonicum strains on formation and function of the legume-rhizobium symbiosis of soybean plants were studied. The data showed that the bacterial compositions B. japonicum 634b + B. subtilis 5, B. japonicum 634b + A. chroococcum 20, and B. japonicum 10k + A. vinelandii 56 with a cell ratio of 1:0.1 increased the number and weight of root nodules as well as the height and weight of the aboveground plant parts in almost all the cases by 22-105% compared with the control variants. These binary microbial cultures may be used for development of combined bacterial preparations for soybean.