[Structural modification of environment by microorganisms: formation of Liesegang rings around Dictyostelium discoideum population].

: The results of the experimental study of the environment modification--the emergence of Liesegang rings around a Dictyostelium discoideum population are presented. The formation of Liesegang rings induced by D. discoideum cells is observed on addition of glucose into the semi-solid nutrient medium (agar concentration 0.5-1.5%). We show that the emergence of Liesegang rings is attended with a redistribution of folic acid in the nutrient substrate. A pH decrease in the course of D. discoideum cultivation is shown to be a factor inducing the redistribution of folic acid. The mechanisms of structural modification of the D. discoideum environment are discussed.