The Influence of Permafrost Microorganisms on Monocytes Differentiation In Vitro

Abstract

Metabolites of fossil microorganisms of dispersed watered rocks that have passed into a frozen state (Bacillus sp. strains 2/09 and 9/08, Bacillus megaterium 8-75) can modulate the differentiation activity of human peripheral blood monocytes into phenotypically different subpopulations when cultured in vitro for 7 days. This effect is largely determined by the type of metabolites that depends on the temperature of their production: cold (collected after bacterium culturing at 5°C), medium (at 22°C), and warm temperature (at 37°C). All three types of metabolites had a weak negative influence on the level of classical (CD14^hiCD16^-) monocytes and stimulated the differentiation of intermediate (CD14⁺CD16⁺) and non-classical (CD14^loCD16⁺) monocytes. The monocytes differentiation into the subpopulation of intermediate (CD14⁺CD16⁺) was stimulated to a greater extent by medium-temperature metabolites of the strain 8/75 and into the subpopulation of non-classical (CD14^loCD16⁺) monocytes by warm metabolites of the strains 8/75 and 2/09 throughout culturing of mononuclear cells (days 1, 3, 7). Bearing in mind the anti-infection activity of intermediate and non-classical monocytes, we can consider strains 8/75 Bacillus megaterium and 2/09 Bacillus sp. promising for their in-depth testing.

Keywords: bacterial metabolites; monocytes differentiation; monocytes differentiation regulatory factors; monocytes subpopulations; permafrost fossil microorganisms.