Aleksandra V. Kim

This review presents current information on the diversity of bacterial enzyme systems involved in the aerobic and anaerobic oxidation of aliphatic and aromatic hydrocarbons in oil. It is shown that the most common hydrocarbon-oxidizing microorganisms in the marine environment include bacteria of the genera Mycobacterium, Brevibacterium, Nocardia, Corynebacterium, Rhodococcus, and Arthrobacter, which are usually isolated from areas with severe oil pollution. Alcanivorax, Acinetobacter, Achromobacter, Bacterium, Bacillus, Micrococcus, Pseudomonas, Pseudoalteromonas, Psychrobacter, Marinobacter, Marinomonas, Halomonas, Oleispira, Thalassolituus, Oleiphilus, and Shewanella are often mentioned among marine oil oxidizers. Information continues to appear on bacterial taxa for which hydrocarbon-oxidizing activity is described for the first time. Currently, most studies in this field focus on either areas of chronic petroleum hydrocarbon pollution or poorly studied areas, including deep-sea sites. The feasibility of using the microbial potential for the bioremediation of oil-polluted water areas, especially under anaerobic conditions is of particular interest.

We have created microbial consortia from native hydrocarbon-oxidizing bacteria isolated from the Seas of Japan and Okhotsk, which not only have hydrocarbon-oxidizing activity, but also accelerate oil degradation due to additional properties (hydrophobicity to petroleum hydrocarbons, emulsifying and lipolytic activity). In addition to typical oil oxidizers, the consortia included bacteria of the genera Niallia, Rossellomorea and Patulibacter, whose hydrocarbon-oxidizing activity was studied for the first time. The established microbial consortia demonstrated high efficiency of oil oxidation in model experiments at salinity 30–40‰ and temperatures of 5 and 22°C. The degree of oxidation of oil on the 28th day of the experiment was 78–94%.

The cultivation of Panax ginseng C.A. Meyer, a valuable medicinal plant, presents a number of challenges due to its physiology and life cycle. The composition of the soil and the microbiome living in it are important for plant growth and root quality. Modern analytical methods were used to identify differences in the rhizosphere soils of plants in the forest and in the plots. Microbiological and molecular genetic methods were used to isolate and identify bacterial isolates from these soils, allowing for the establishment of a working collection of potentially useful bacterial strains. Increases in soil pH in the plots and changes in the amount of macronutrients partially explained the changes in the activity of the forest and plot isolates and the composition of the cultivated strains. The cultivated strains belonged to the rhizosphere-dominant phyla Pseudomonadota, Bacillota, and Actinomycetota of the main functional groups of soil potassium, phosphorus, and nitrogen transformations. The ratio of bacteria functional groups was comparable in the forest and in the plots. The most common phylum of cultured microorganisms was Bacillota, while the main differences were observed in the functional group of potassium-solubilizing bacteria belonging to the phyla Pseudomonadota.

Enterococci have acquired resistance to almost all classes of antibiotics. The purpose of this study was to study and analyze the resistance of Enterococcus bacteria to antibiotics isolated from Vladivostok water bodies. The antibiotic resistance of 70 strains of the genus Enterococcus to such antibiotics as tetracycline, streptomycin, erythromycin, ampicillin, levofloxacin, rifampicin, gentamicin, vancomycin was studied by disco diffusion. It turned out that in b. In the b. Zolotoy Rog, more than half of the isolated strains were resistant to streptomycin, erythromycin, and levofloxacin, and in the r. Vtoraya Rechka, more than 50 % of the strains were resistant to streptomycin and rifampicin. The isolated population of enterococcal strains was characterized by multiple resistance to two antibiotics (41 %) in the Second River and three or more antibiotics (45 %) in the Golden River. The most common was resistance to a combination of antibiotics such as streptomycin, rifampicin and erythromycin.

Environmental problems associated with marine pollution and climate warming create favorable conditions for the penetration and survival of pathogenic bacteria in marine ecosystems. These microorganisms have interspecific competitive interactions with marine bacteria. Co-culture, as an important research strategy that mimics the natural environment of bacteria, can activate silent genes or clusters through interspecies interactions. The authors used modern biotechnology of co-cultivation to dynamically study intercellular interactions between different taxa of bacteria—pathogenic enterobacteria Yersinia pseudotuberculosis and Listeria monocytogenes and saprotrophic marine bacteria Bacillus sp. and Pseudomonas japonica isolated in summer from the coastal waters of the recreational areas of the Sea of Japan. The results of the experiments showed that during the formation of polycultural biofilms, horizontal transfer of genes encoding some pathogenicity factors from Y. pseudotuberculosis and L. monocytogenes to marine saprotrophic bacteria with different secretion systems is possible. It was previously thought that this was largely prevented by the type VI secretion system (T6SS) found in marine saprotrophic bacteria. The authors showed for the first time the ability of marine bacteria Bacillus sp. and P. japonica to biofilm formation with pathogenic enterobacteria Y. pseudotuberculosis and L. monocytogenes, saprophytic bacteria with type III secretion system (T3SS). For the first time, a marine saprotrophic strain of Bacillus sp. Revealed manifestations of hyaluronidase, proteolytic and hemolytic activity after cultivation in a polycultural biofilm with listeria. Saprotrophic marine bacteria that have acquired virulence factors from pathogenic enterobacteria, including antibiotic resistance genes, could potentially play a role in altering the biological properties of other members of the marine microbial community. In addition, given the possible interdomain nature of intercellular gene translocation, acquired virulence factors can be transferred to marine unicellular and multicellular eukaryotes. The results obtained contribute to the paradigm of the epidemiological significance and potential danger of anthropogenic pollution of marine ecosystems, which creates serious problems for public health and the development of marine culture as an important area of economic activity in coastal regions.

Taxonomic structure of bacterial community for mussel Crenomytilus grayanus digestive system from coastal waters of Vladivostok city, which is characterized by considerable anthropogenic impact was studied. Specimens of Micrococcaceae family predominated in the mollusc microscopic flora by the quantity of selected strains (62%). The order of Actinomycetales (namely genera of Actinomyces and Pimelobacter) were large (11%). In addition, there were numerous representatives of Enterobacteriaceae family (9%), Vibrio genus (9%), and Paracoccus genus (9%) selected. There were found such pathogenic and opportunistic microorganisms, as Escherichia coli, Listeria monocytogenes, and Klebsiella spp in microbial communities of mussels. Even though pathogenic microflora does not predominate in the biotic community, it nevertheless shifts the balance to increase extrinsic microflora within the hydrobiont. Detection of such potentially harmful bacteria indicates the insufficient sanitary and epidemiological state of the water area researched, the bay persistently polluted with municipal domestic drain waters.

By means of molecular biology techniques, metabolic potential of microbial communities within the regions of inshore water areas in the Sea of Japan with various anthropogenic load was explored. Presence of functional genes, responsible for oil hydrocarbons destruction, for microbial communities within the regions of inshore water areas in the Sea of Japan was first researched. In total microbial DNA from water mass in the regions with chronic anthropogenic pollution, the genes, responsible for oxidation of broad range of n-alkanes and polycyclic aromatic hydrocarbons, were found. Detection of marker genes in the background water area (in the Vostok Bay) was ever indicating ecological deterioration within this territory. Thereby, it was demonstrated, that molecular genetic methods, aimed at marker gene detection in total bacterial DNA from environment objects, proved themselves to be more effective technique for identification of oil hydrocarbons water pollution, in comparison with trivial culturable methods.