Diversity of sediment bacterial communities in the South Eastern Arabian Sea

The bacterial community structure in the surface sediments of the South Eastern Arabian Sea (SEAS) was assessed using high-throughput Illumina based sequencing. An attempt was also made to evaluate the role of environmental variables on the distribution of the bacterial community. A total of 53 phyla, 111 classes, 155 orders, 179 families, and 215 genera were detected in the study area. There was no significant difference in the major bacterial communities between nearshore and offshore stations whereas the relative abundance of the majority of OTUs showed station/depth wise variation. Proteobacteria was the dominant phylum observed in all the stations, which ranged from 50.3% to 59.9% of the total sequences retrieved. Other abundant phyla observed were Chloroflexi (7.4% of total sequences), Actinobacteria (6.4%), Acidobacteria (5.5%), Nitrospirae (2.7%), Gemmatimonadetes (2.4%), Bacteroidetes (1.5%), candidate phylum "Latescibacteria" (1.4%), and Spirochaetes (1.1%). All the remaining phyla were observed in lower numbers, comprised of <1% of the total sequences. Within the Proteobacteria 63.8% of sequences were Deltaproteobacteria, 21.8% were Gammaproteobacteria and 1.6% were Alphaproteo bacteria. The dominant genera observed within the phylum Proteobacteria were Photo bacterium, Desulfococcus, Acinetobacter, Pseudomonas, Marinobacter, Nitrospina, and Desulfosarcina. The dominant genera observed under the phylum Chloroflexi were Dehalococcoides, Anaerolinea, Caldilinea, and Thermogemmatispora. Among the environmental variables, total nitrogen and total sulphur were showed influence on the OTUs distribution in the study area. The dominant phyla in the SEAS such as Pro teobacteria, Chloroflexi and Nitrospirae were also significantly influenced by these environmental variables. (C) 2020 Elsevier B.V. All rights reserved.