Abstract
The Black Sea is a unique environment having a thin layer of oxic-zone above and anoxic-zone below. Seasonal, vertical, and horizontal microbial assemblages were studied in terms of diversity, abundance, community structure using NGS of the 16S rRNA gene. Total of 750 bacteria species from 23 different phyla were identified. The number of species richness increased from the surface to deeper zones. Although microbial community compositions between sampling stations were similar, microbial community compositions were significantly different vertically between zones. Community compositions of the seawater and sediment were also significantly different. Community composition at 5 meters in summer was significantly different from other seasons, while remaining depths appeared similar. Species of nitrite-oxidizing, sulfate-reducing, thiosulfate reducing, Iron-reducing, Fe-Mn reducing and electricity-producing bacteria were reported for the first time in the Black Sea. Proteobacteria dominated all the sampling depths. Proteobacteria, Cyanobacteria, Bacteroidetes, and Verrucomicrobia were present in the whole water column, while Nitrospinae, Chloroflexi, and Kiritimatiellaeota were restricted, appearing abundant at 75 meters and deeper layers. Vertical microbial community composition variation is attributable to environmental factors and their adaptations to the various ecological niches.
Fingerprinting Microbial Assemblages from the Oxic/Anoxic Chemocline of the Black Sea
