The ability of a variety of bacteria isolated from soil samples with high levels of magnetism of the city Mednogorsk to oxidize iron (II) in conditions of periodic cultivation in a liquid medium was studied. Investigating the increase in total biomass using its wet weight and analyzing its absolute bacterial biomass growth after 7 and 14 days of cultivation resulted in the identification of two microbial isolates with maximum growth rates. The wet biomass weight of these isolates (69.3 and 69.5) was 15.3 and 14.7 g/l after 14 days of cultivation.