The structural modification of environment by microorganisms: the 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 ce lls 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 ri ngs is attended with a redistribution of folic acid in the nutrient substra te. 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 stru ctural modification of the D. discoideum environment are discussed.