Some Characteristics of Actinomycetes Isolated from the Soil of the Belgorod Region ^†

Microorganisms of various systematic groups, such as fungi, bacteria and actinomycetes, represent an inexhaustible source of biologically active substances that can be used in various fields of human activity. Among them, actinomycetes of the genus Streptomyces stand out as producers of many promising metabolites. These Gram-positive filamentous bacteria are widespread in soil and marine sediments, and synthesize most clinically important antibiotics, attracting high interest in the pharmaceutical and industrial fields. It is important to note that not all Streptomyces strains have been fully studied, which opens up additional prospects for their study.

The purpose of this work was to characterize pigment-synthesizing actinobacterial isolates.

A soil sample from the Belgorod region, Russia, was taken for this study. The isolation of the bacterium was carried out by serial dilution on LB nutrient medium (composition g/l: Peptone-10, Yeast extract-5, NaCl-5, agar-agar-20). The isolates were characterized using standard biochemical, morphometric and genetic tests.

Twelve bacterial strains were isolated, the morphometrical characteristics of which allowed them to be presumably attributed to the order actinomycetes. One of the strains, GB43, was capable of synthesizing pink pigment. On solid LB medium, strain GB43 formed convex, round pink colonies with an uneven edge growing into the nutrient medium. This strain was tentatively identified as Streptomyces griseoaurantiacus based on phylogenetic analysis of the 16S rRNA gene. Isolate BG43 showed pronounced antimicrobial activity against phytopathogenic fungi and bacteria, which makes it promising for plant protection biotechnologies.