The article discusses aspects of the interaction of Escherichia coli (25922) and Staphylococcus aureus (209-P) with particles of natural minerals (zeolititic tuff from some deposits in the Far East and Siberia, Russia) using size fractions 0.1-1, 1-10 and 10-50 μm. It is shown that particles 0.1-1 and 10-50 μm in size have virtually no effect on microorganisms. Whereas microparticles (1-10 μm) from different deposits have a significant effect depending on the type of a rock-forming mineral: clinoptilolite has a bacteriostatic effect, and mordenite – bacteriostimulating effect.