Assessing ability of B. Elkanii strains to accumulate high titers of bacterial cells in liquid culture during deep cultivation on nutrient media of various compositions

The field experiments conducted in 2020 – 2021 helped select 4 strains of Bradyrhizobium elkanii (Kuykendall et al., 1992) (By-9, By-11, By-25 and Bp-29) obtained from the nodules of V. radiate, V. unguiculata cowpea that demonstrated high efficiency on soybeans. These strains were assessed in terms of their ability to accumulate a titer of bacterial cells on nutrient media of various compositions during deep cultivation in laboratory fermenter TN -50L (70 rpm) being 50 liters in volume and having an air compressor (power – 1.1 kW, maximum pressure – 0.7 MPa, volume of produced gas – 0.11 m3). Cultivation was performed at a temperature of 28±1 °C. The CFU titer and pH of the medium were determined after 24, 48 and 72 hours of cultivation. It was found out that the most efficient strain for the production of microbiological fertilizers in terms of its ability to accumulate the maximum titer of active cells on both liquid nutrient media is By-25.