Oil Pollution Assessment of Coastal Marine Water Areas of the Kamchatka Peninsula Based on Microbial Indication

Based on microbial indication results for 2023 and 2024, it is established that Avacha Gulf and the southwestern coast of Kamchatka are subject to significant oil pollution. The number of hydrocarbon-oxidizing microorganisms at most of the studied stations was 10³ CFU/mL (g) and higher. The results of molecular genetic analysis identifying marker bacterial genes for the oxidation of alkanes (ALK-1, ALK-2, and ALK-3) and PAHs (nah, phn, bphA1, xylE, GN-PAH, and GP-PAH) in the environment indicated the dominance of bacteria capable of oxidizing short- and medium-chain alkanes in the surface waters of Avacha Gulf in 2023 and bacteria that are potential destructors of medium- and long-chain alkanes in the waters of the southwestern coast of Kamchatka. Also, the waters of both areas were characterized by a significant presence of gram-negative bacteria that oxidize various types of PAHs. In 2024, the proportion of stations with bacteria that degrade phenanthrene and short-chain alkanes sharply decreased in Avacha Gulf, but the proportion of stations with microorganisms that oxidize long-chain alkanes increased. An increase in the proportion of water samples with bacterial biphenyl oxidation genes and PAH oxidation genes of gram-negative microbiota was noted for the southwestern coast of Kamchatka. In bottom sediment samples collected in 2023 from both study areas, the genes responsible for PAH oxidation by gram-positive microbiota and for the degradation of long-chain alkanes were most often detected. An analysis of bottom sediment samples collected in 2024 indicated a decrease in the proportion of stations with microorganisms capable of oxidizing various petroleum hydrocarbons (PHs) in both study areas.