engleski

Epibiotic Cyanobacteria Associated with Sea Turtles – from Metabarcoding to Culturing

An increasing number of studies have shown that sea turtle-associated biofilms are highly diverse and contain epibionts different from the ones that are found in other marine benthic biofilms. A sea turtle’s carapace and skin can be the home to a large variety of macro-epibionts (e.g., barnacles, green and red algae) and micro-epibionts (e.g., bacteria, diatoms, protozoa), and many of them are found exclusively on sea turtles. Cyanobacteria are known for establishing symbiotic relationships with different hosts, however, little is known about the cyanobacteria associated with sea turtles. Recently, cyanobacteria have gained more attention as an important part of the sea turtle microbiota, but little is known about their identity, ecological role, or their possible effect on a sea turtle host and vice versa. Our previous research on cyanobacteria within the epizoic biofilm of 26 turtles (via amplicon sequencing of the V4 region of the 16S rRNA gene) showed that cyanobacteria comprised 3% of all ASVs on average, ranging from 0.01 to 19.77% across individual samples. More than 20 cyanobacterial families were found living on Mediterranean loggerheads, with the four most abundant being Phormidesmiaceae, Paraspirulinaceae, Xenococcaceae, and Limnotrichaceae. However, a large proportion of the sequences remained unidentified. To reduce this knowledge gap, we aimed to culture epizoic cyanobacteria sampled from microbial biofilm growing on sea turtles. The biofilm samples were enriched in ASN-III culture medium under 12h light period at 20 °C and single cells or colonies are picked using micropipette under inverted light microscope. Two xenic Phormidium-like cyanobacterial strains were obtained from the loggerhead carapace biofilm, they were examined morphologically using scanning electron and light microscopy. Their DNA was isolated and 16S sequences obtained, contributing to polyphasic characterization of the strains. Marker gene sequences from those cultures will contribute to the reference database and more accurate DNA barcoding and metabarcoding hits of cyanobacterial taxa in the future. Hopefully, this research will help better understand understudied cyanobacterial communities associated with vertebrate hosts.

cyanobacteria ; sea turtles ; metabarcoding ; cultures

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