Cultural and physiological characteristics of <i>Sinorhizobium fredii</i> strains selected by the All-Russian Scientific Research Institute of Soybean and their ability to produce vitamins В₉ and В₁₂

Abstract

Relevance. Microorganisms that stimulate plant growth (PGPB), including rhizobia, improve plant productivity through various physiological, molecular and biochemical effects. Of the above factors, the role of vitamins has been studied to a lesser extent. For assessing the ability of rhizobia to produce vitamins В9 и В12, Sinorhizobium fredii strains were selected, which represent a homogeneous group and had good and abundant biomass growth on various nutrient media. Methods. The cultural and physiological properties of the strains were studied using generally accepted laboratory microbiological methods. Passages of collection strains of rhizobia and the study of various properties of these bacteria were carried out on nutrient media MDA and MRS, and on production nutrient media RM and TY produced by HIMEDIA company (India). Determination of the sensitivity of S. fredii strains to antibiotics was carried out using the disc diffusion method. The content of vitamins B9 and B12 in the bacterial mass of rhizobia was determined by the chemiluminescent immune method with the use of paramagnetic particles, and by applying immunochemical Access systems, on the chemiluminescence analyzer Access2. Results. It was found that the studied strains S. fredii have good or abundant growth of bacterial mass on nutrient media MRS, MDA, RM and TY. They are catalase-positive, have high and medium resistance to antibiotics. The highest concentration of vitamin B9 in biomass was synthesized by strains SB-39 (75.0 pg/ml), BB-49 (66.6 pg/ml) and TB-488 (48.9 pg/ml), and vitamin B12 — by strains BB-49 and SB-39 (1500 pg/ml).