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.

The concentrations of 14 polycyclic aromatic hydrocarbons (PAHs) in the sediment of the Tatar Trough were studied. Despite the increase in PAH concentrations over recent decades, which is likely the result of the handling and transportation of fossil fuels, PAH levels and ecological risk were found to be low. The spatial pattern revealed that higher PAH concentrations were mainly in the deeper water sites, suggesting that trough slope failure transported the PAHs to the deeper part of the basin. There was no correlation between the PAHs and grain size or the PAHs and organic carbon that is related to the PAH input from a variety of sources and the heterogeneity of organic matter. The PAH composition, isomer ratio, and PCA identified two areas with different PAH sources. The most northern part of the Tatar Trough received petrogenic PAHs that are probably transported downslope from the northern Tatar Strait where fossil fuels are handled in some ports. Another trough part was polluted by the PAHs from the combustion of coal and biomass and the exhaust of marine vehicles. The minor presence of genes responsible for aerobic PAH destruction can be explained by the anaerobic degradation of PAHs or the spontaneous creation of favorable conditions that promote bacterial PAH oxidation.

A new sulfate-reducing strain SRJS8^T with a high ability to biodegrade petroleum hydrocarbons was isolated from the bottom sediments in the northern part of the Sea of Japan. The cells were gram-positive, spore-forming, singlemotile rods 0.4–0.5 × 2.0–5.0 µm in size. Strain SRJS8^T grew at the temperature range from 6 to 30°C (optimum, 25°C), pH 6.3–7.7 (optimum, 7.3), and NaCl concentrations ranging from 0 to 20 g/L (optimum, 2 g/L). Strain SRJS8^T utilized butanol, glycerol, methanol, ethanol, butyrate, lactate, pyruvate, formate, yeast extract, H₂/CO₂, and crude oil as electron donors and carbon sources in the presence of sulfate. SRJS8^T utilized sulfate, sulfite, thiosulfate, elemental sulfur, fumarate, and Fe(III) as electron acceptors in the presence of lactate. The closest relative of the SRJS8^T was Desulfosporosinus lacus STP12^T (similarity, 98.49%). The complete genome of the strain SRJS8^T (5.43 Mb) was sequenced. DNA–DNA homology of strain SRJS8^T and D. lacus was 57.4%, and the ANI value was 93.69%. The genomic DNA G+C content was 42.08%. In accordance with the obtained data, SRJS8^T was assigned to a novel species within the genus Desulfosporosinus, for which the name Desulfosporosinus shakirovi sp. nov. is proposed. The type strain is SRJS8^T (=VKM B-3489^T, =JCM 39 189^T).

The bioindication of oil and gas fields is a field of geomicrobiology that is mainly devoted to the detection of hydrocarbon-oxidizing microbial indicator species or functional genes in total DNA. However, it appears promising to use the physiological properties of microorganisms detection deposit type of hydrocarbons, in particular their ability to oxidize hydrocarbons under aerobic and anaerobic conditions. In this study, the most promising approach in this area was the method used for assessing the anaerobic degradation of hydrocarbons. When comparing molecular genetics and cultured methods of bioindication, it can be concluded that molecular biomarkers of functional genes for the anaerobic destruction of hydrocarbons (masD) make it possible to separate areas with traditional and gas-hydrate types of deposits. Using cultured methods, we found that representatives of the Nocardiaceae family of the phylum Actinomycetota were tied to the areas where gas hydrates were found. The ability of aerobic and facultative anaerobic hydrocarbon-oxidizing microorganisms to anaerobically utilize hydrocarbons was determined with cultured methods. For the first time, this ability was revealed for the genera Stenotrophomonas, Psychrobacter, Micrococcus and Peribacillus. The wide distribution of this ability that we found in strains isolated from both study regions suggests its prominent role in the destruction of hydrocarbons in marine sediments.

This review examines the role of sulfate-reducing bacteria in the anaerobic degradation of hydrocarbons in marine sediments, where they contribute to the mineralization of organic matter under anoxic conditions. The metabolic diversity of these microorganisms is described, including their ability to degrade various classes of hydrocarbons such as short-chain (C₂–C₅), medium-chain (C₆–C₁₂), and long-chain (C₁₃–C₂₀₊) alkanes, alkenes, and aromatic compounds like naphthalene and phenanthrene. The primary mechanisms involved in the initial activation of these hydrocarbons—fumarate addition and carboxylation—are discussed, along with key enzymes, including alkylsuccinate synthase and benzylsuccinate synthase. Syntrophic interactions are also considered, particularly in which archaea initiate the oxidation of short-chain alkanes (e.g., ethane and butane), with sulfate-reducing bacteria serving as terminal electron acceptors via sulfate reduction. The potential application of these anaerobic processes in bioremediation strategies for oil-contaminated marine sediments is discussed. This microbially mediated degradation may offer a complementary approach to aerobic methods, particularly in oxygen-limited environments. Understanding the activity of sulfate-reducing bacteria activity is relevant to several areas: the development of remediation techniques for anoxic zones, the assessment of methane emissions from marine sediments, the management of microbiologically influenced corrosion, and potential biotechnological applications. Current research directions include the study of syntrophic microbial consortia and the exploration of bioelectrochemical systems.