Groups of Geomicrobiological Indicators Are Spread across Gas-Hydrate and Non-Gas-Hydrate Areas in the Northern Part of the Sea of Japan

Simple Summary The bioindication of oil and gas fields is an important task in geomicrobiology. Our study expands the field of geomicrobiological methods and allows us not only to suggest the possibility of the presence of an oil and gas deposit but also its type. We used cultural and molecular genetic methods to study microorganisms, in particular their ability to oxidize hydrocarbons under aerobic and anaerobic conditions. We carried out a comparative analysis of cultured and molecular methods for the bioindication of oil and gas deposits to detect deposits and describe the relevant types(traditional and gas-hydrate). The most promising method in this area was the one used for assessing the anaerobic degradation of hydrocarbons. Studying the mcrA, pmoA, dsrB, alkBB, bssA and masD biomarker genes made it possible to identify areas with different types of deposits based on the distribution of the alkBB, bssA and masD genes. The bssA and masD genes predominated in the gas-hydrate region. With the help of cultured methods, it was possible to describe the type of deposits based on taxonomic diversity (Rhodococcus spp.). In addition, the ability of aerobic and facultative anaerobic hydrocarbon-oxidizing microorganisms to anaerobically utilize hydrocarbons was described using cultured methods. 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.