ISOLATION OF ACTINOBACTERIES FROM THE SOIL FERROSPHERE AND THEIR IDENTIFICATION

Actinobacteria is one of the bacterial groups important in terms of biofilm formation. Among them, representatives of Streptomyces sporoactinobacteria, some of the most active soil ammonifying bacteria, deserve attention. It is known that ammonifying bacteria are involved in microbially induced corrosion in the first stages of biofilm formation and form ammonia – a corrosion-dangerous metabolite. However, their diversity in soil ferrosphere remains poorly understood. The purpose of the work is the isolation of an actinobacterium strain from the soil ferrosphere and its identification.

The work was carried out by conventional methods: general biological (preparation of mounts "crushed drop", stained smears, microscopy), microbiological (preparation of medium for the cultivation of bacteria, the method of ten-fold dilutions, Koch’s method, seeding microorganisms in a liquid and agar medium, methods of staining of cells of bacteria and their structures (staining with fuchsin, methylene blue, Gram staining method in Kalina’s modification), methods of determining physiological and biochemical properties (tests for catalase, oxidase, utilization of citrate, casein, fats, starch, urea, formation of indole, ammonia, hydrogen sulfide, MRVP-test, relation to oxygen and temperature), molecular-genetic (isolation of DNA from bacterial cells, polymerase chain reaction with primers for 16S rRNA gene, 16S rRNA gene sequencing, horizontal agarose gel electrophoresis, phylogenetic analysis using GenBank database and MEGA 6.0 computer program).

Scientific novelty – from the soil ferrosphere is isolated a strain of actinobacteria, which by the complex of microbiological, physiological and biochemical properties and based on the sequence of the 16S rRNA gene fragment (according to the results of phylogenetic analysis) is classified as Streptomyces canus. It develops and expands the understanding of the diversity of corrosive bacteria and a set of test cultures for the study of microbial-induced corrosion processes.

Conclusions – according to a number of microbiological, physiological, biochemical and genetic characteristics, the NUChC F2 strain is classified as Streptomyces and identified as Streptomyces canus. The nucleotide sequences of the 16S rRNA gene were registered in the GenBank database as Streptomyces сanus MG924748 and MG924855. The isolated strain is ammonifying, thus potentially corrosion-active, and can be used in the study of microbial-induced corrosion processes. According to the level of biosafety, bacteria of the S. canus species belong to the 1st risk group (according to the German Technical Rules for biological agents) and are safe for human health.