engleski

More than just hitchhikers: a survey of bacterial communities associated with diatoms originating from loggerhead sea turtles

Diatoms and bacteria are the first colonizers of submerged surfaces (non-living and living), including the skin and carapace of sea turtles where they can form biofilms. Multiple studies point to the prevalence and ecological importance of diatom-bacteria interactions in phytoplankton ; however, little is known about diatom-bacteria associations in epizoic biofilms. This study aimed to investigate the bacterial communities associated with diatoms present on loggerhead sea turtles, some of which are exclusively epizoic. To investigate the diatom and bacterial communities of epizoic biofilms we employed a PCR- based metabarcoding approach combined with diatom/bacteria cultivation. We isolated diatoms from carapace and skin samples and established xenic monocultures. Diatom communities in source samples were surveyed via rbcL metabarcoding, while monoclonal cultures were identified based on morphology and rbcL gene sequencing. Bacteria within the diatom cultures were isolated and cultured for full 16S rRNA gene sequencing, while amplicon sequencing of the V4 region of the 16S rRNA gene enabled bacterial community characterisation within diatom monocultures and diatom source samples. The lack of representative sequences in rbcL database Diat.barcode made it difficult to detect understudied epizoic diatoms by metabarcoding surveys. Bacterial communities associated with diatom strains reflected their source sample based on bacterial taxa composition, and there are indications that similar diatom genera retain related bacterial taxa. Alcanivoracaceae, Marinobacteraceae, Phycisphaeraceae families were enriched in diatom cultures with readily culturable representatives. In conclusion, loggerhead sea turtles have been shown to be colonized by often understudied diatoms whose bacterial communities might reveal important diatom-bacteria associations in epizoic biofilms.

phycosphere ; microbiome ; sea turtles

Diatoms and bacteria are the first colonizers of submerged surfaces (non-living and living), including the skin and carapace of sea turtles where they can form biofilms. Multiple studies point to the prevalence and ecological importance of diatom-bacteria interactions in phytoplankton; however, little is known about diatom- bacteria associations in epizoic biofilms. This study aimed to investigate the bacterial communities associated with diatoms present on loggerhead sea turtles, some of which are exclusively epizoic. To investigate the diatom and bacterial communities of epizoic biofilms we employed a PCR-based metabarcoding approach combined with diatom/bacteria cultivation. We isolated diatoms from carapace and skin samples and established xenic monocultures. Diatom communities in source samples were surveyed via rbcL metabarcoding, while monoclonal cultures were identified based on morphology and rbcL gene sequencing. Bacteria within the diatom cultures were isolated and cultured for full 16S rRNA gene sequencing, while amplicon sequencing of the V4 region of the 16S rRNA gene enabled bacterial community characterisation within diatom