Microbial community associated with Aplysia depilans egg strings and surrounding seawater, containing multiple bacterial taxa detected by 16S rRNA gene sequencing. Raw sequence reads

This project investigates the bacterial communities associated with the egg strings of the marine opisthobranch Aplysia depilans and the surrounding seawater environment, with the aim of identifying potential microbial assemblages that may play ecological roles in embryo protection and development. Egg strings are complex gelatinous structures that serve as both physical and biochemical barriers against abiotic stressors, microbial colonization, and predation in the intertidal environment.To examine the microbial composition of these structures, DNA was extracted from four egg string samples and three 2 L surrounding seawater samples, and subjected to 16S rRNA gene amplicon sequencing using the Ion Torrent S5 platform. Libraries were prepared with the Ion 16S Metagenomics Kit, targeting six hypervariable regions (V2, V3, V4, V6-7, V8, and V9) of the bacterial 16S rRNA gene. The generated reads were processed using Torrent Suite v5.18 for quality control and demultiplexing, followed by taxonomic classification in Ion Reporter Software (Thermo Fisher Scientific) using the 16S Metagenomics workflow.Taxonomic assignments were based on a two-step BLAST alignment approach against the MicroSEQ ID bacterial reference library and the Greengenes database, applying the Clinical and Laboratory Standards Institute (CLSI) identity thresholds: less than 97 percent for family-level, greater than 97 percent for genus-level, and greater than 99 percent for species-level assignments. Unclassified reads were retained at the lowest taxonomic rank possible.The resulting dataset provides a reference for the bacterial taxa associated with Aplysia depilans egg strings and local seawater, offering insights into microbial diversity in coastal marine environments and supporting future studies on host-microbe interactions in invertebrate egg masses. The BioProject includes raw sequence reads and corresponding sample metadata for public reuse and comparative analyses.