engleski

Multi-domain investigations of microbial communities associated with loggerhead sea turtles

Marine vertebrates are hosts to myriads of microorganisms. Bacteria and diatoms are known for being the first colonizers of submerged surfaces, including the skin and carapace of loggerheads where they establish multi-domain biofilms. Recent studies point to the prevalence and ecological importance of interactions between bacteria and planktonic diatoms, but to date, little is known about bacteria-diatom interactions in biofilms associated with epizoic diatoms. Furthermore, it is known that loggerheads harbour diatom taxa specific to marine vertebrate hosts ; however, it is not known if this is the case for bacteria and how important diatom taxa within these communities are. This study aimed to investigate the bacterial repertoire of diatoms associated with sea turtles, as well as to gain insight into the diatom community dynamics and host exclusivity by investigating putative epizoic and non-epizoic diatoms via co-cultivation. We isolated diatoms from carapace and skin scrapings of loggerhead sea turtles and established xenic monocultures. Bacteria within diatom cultures were investigated by culturing and partial 16S rRNA gene sequencing, and amplicon sequencing of the V4 region of 16S for bacterial communities within diatom monocultures and their source sample. Additionally, putative epizoic and non-epizoic diatoms were co-cultivated to examine their growth both in monocultures and co-cultures. Microbial communities differed between diatom genera and their phycospheres were enriched in Alcanivoracaceae, Marinobacteraceae, Phycisphaeraceae families. Initial co-culturing results show a faster growth of epizoic diatoms in co-culture with non-epizoics. This research provides first insights into the biology of microeukaryotes within epizoic biofilms and their associated bacteria.

diatoms ; bacteria ; sea turtles ; microbiota ; cocultures

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