Short-Term Exposure to Sterile Seawater Reduces Bacterial Community Diversity in the Sea Anemone, Exaiptasia diaphana

Abstract

The global decline of coral reefs heightens the need to understand how corals may persist under changing environmental conditions. Restructuring of the coral-associated bacterial community, either through natural or assisted strategies, has been suggested as a means of adaptation to climate change. A low complexity microbial system would facilitate testing the efficacy of microbial restructuring strategies. We used the model organism for corals, Exaiptasia diaphana, and determined that short-term (3 weeks) exposure to filter-sterilized seawater conditions alone reduced the complexity of the microbiome. Metabarcoding of the V5–V6 region of the bacterial 16S rRNA gene revealed that alpha diversity was approximately halved in anemones reared in filter-sterilized seawater compared to controls reared in unfiltered seawater and that the composition (beta diversity) differed significantly between the two. By reducing the complexity of the E. diaphana microbiome, the development of a system for testing assisted strategies such as probiotics, is more feasible.

Microbiome characterization of defensive tissues in the model anemone Exaiptasia diaphana

“…Each point is an individual sample. Whole anemone data were used with permission from [47]. For each genotype, bacterial communities were different between acontia and whole anemones (PERMANOVA, 999 permutations).…”

“…To investigate which bacteria are enriched in acontia, we compared our dataset with data obtained from whole anemones belonging to the same genotypes and clonal populations, reared in the same conditions, and processed in the same way as in the present study [47]. PCoA visualization using the Bray-Curtis dissimilarity index showed a high degree of clustering by source, with all acontia data points being clearly separated from all anemone data points (Fig.…”

“…Whole anemone data used for indicator value analysis was previously published (PRJNA576556 [47];) These data were obtained from whole anemones deriving from the same clonal populations used for acontia sampling. Anemones from both studies were derived from the same clonal populations, maintained in the same lab and in the same rearing conditions.…”

“…Raw Illumina MiSeq data from acontia are available under NCBI BioProject ID PRJNA650220. Raw Illumina MiSeq data from whole anemones [47] are available under NCBI BioProject ID PRJNA576556.…”

Development of a free radical scavenging bacterial consortium to mitigate oxidative stress in cnidarians

“…diaphana have revealed a similar diversity at the phylum level for E . diaphana sourced from the GBR (Hartman et al ., 2020; Dungan et al ., 2021), Hawaii (strain H2; Herrera et al ., 2017), Pacific and Caribbean (Brown et al ., 2017), Atlantic (strain CC7; Röthig et al ., 2016) and Red Sea (Ahmed et al ., 2019), as well as stony corals (Blackall et al ., 2015). Thus, our culture collection of E. diaphana bacterial isolates captures the diversity of the E. diaphana –associated microbiome.…”