engleski

Bacterial diversity of Mediterranean loggerhead sea turtles’ skin and carapace

The healthy, balanced surface-associated microbiota of humans and other animals are beneficial for their host immunity and overall wellbeing. However, the microbiomes of wild animals are rarely studied due to a general lack of commercial interest. Among these, reptiles are one of the most understudied groups in this regard. In recent years, there has been a growing interest in sea turtle microbiome research, with most of the studies focused on endo-microbiota, i.e. gastrointestinal, faecal, cloacal, and oral bacterial communities. The current study is the first to describe the diversity of epibiotic bacteria associated with loggerhead sea turtles using a culture-independent amplicon sequencing approach. DNA was extracted from the skin and carapace biofilm samples collected from 26 loggerheads from the Adriatic, Ionian, Aegean, and Tyrrhenian Seas. The V4 region of 16S rRNA gene was sequenced using Illumina MiSeq next-generation sequencing, and the obtained data were bioinformatically processed. Amplicon sequencing yielded 6, 242, 910 high-quality ASVs (amplicon sequence variants). The main factors influencing bacterial communities were the locality and the sampled body site (skin or carapace). Phylogenetic diversity and ASV richness were higher in the carapace than in the skin samples. The Ionian and Tyrrhenian turtles harboured the most and least diverse bacterial communities, respectively. Phyla Proteobacteria and Bacteroidota dominated in the highest number of samples. The most abundant bacterial family was Rhodobacteraceae. The five core ASVs (features found in all samples) were identified, four of which belonged to Gammaproteobacteria and one to Oligoflexalia. This study expands the current knowledge about the epi- microbiota of sea turtles and contributes to a better understanding of the complexity of wild animal microbiomes. Future studies may shed light on the possible links between the epi-microbiota and the wellbeing of sea turtles.

microbiome ; epizoic ; Caretta caretta ; metabarcoding ; 16S

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