Culture-Dependent Taxonomic Diversity and Phylogenetic Relationships of Marine Sediment Bacteria from Qantab Bay, Sea of Oman

Abstract

Marine sediments support diverse bacterial assemblages, but culture-dependent surveys recover only the subset able to grow under defined laboratory conditions. Here, we characterized culturable bacteria from nine shallow sediment stations (4–7 m) in Qantab Bay, Sea of Oman, using Actinomycete Isolation Agar (AIA), Starch Casein Agar (SCA), and M1 medium. Forty-four isolates were identified by 16S rRNA gene sequencing and examined phylogenetically. The collection comprised Pseudomonadota (81.8%), Bacteroidota (9.1%), Bacillota (6.8%), and Actinomycetota (2.3%). Recovery differed among media: AIA yielded 23 isolates representing ten genera, M1 yielded 17 isolates representing seven genera, and SCA yielded four isolates representing two genera. Sampling-station provenance was available for 39 isolates across six contributing stations. Vibrio and Pseudoalteromonas were frequently recovered; several closely related Vibrio taxa could not be resolved confidently to species level using 16S rRNA gene sequences alone. Recovery patterns were shaped by the cultivation and isolate-selection procedures. The resulting collection establishes a culture-based taxonomic baseline for coastal marine sediments of Qantab Bay and provides viable isolates for future ecological and genomic investigation.