FIELD: microbiology, genetics. SUBSTANCE: after multiple passage resulting to accumulation clones in population that form atypical by morphology colonies the obtained culture B. anthracis is inoculated on the solid nutrient medium, incubated firstly at 37 C and then at the room temperature up to appearance of expressed morphological distinctions between colonies and colonies in S-form are selected followed by their testing for ability to form spores. Using L-agar with addition of dye Congo red as medium for culture inoculation the invention proposes to carry out selection by two traits simultaneously: morphology of colonies and pigment sorption. Invention proposes variant of method that involves transposon mutagenesis (Tn 917 as component of thermoeliminable plasmid pLTV3ts) is performed before inoculation instead step of culture passage. Invention provides effective preparing asporogenous strains based on broad range of anthrax microorganism cultures. Invention can be used in genetic construction of anthrax strains as producers of biologically valuable substances. EFFECT: improved method of preparing. 4 cl, 4 ex
