Revealing Holobiont Structure and Function of Three Red Sea Deep-Sea Corals

摘要

Deep-sea corals have long been regarded as cold-water coral; however a reevaluationof their habitat limitations has been suggested after the discovery ofdeep-sea coral in the Red Sea where temperatures exceed 20˚C. To gain furtherinsight into the biology of deep-sea corals at these temperatures, the work in thisPhD employed a holotranscriptomic approach, looking at coral animal host andbacterial symbiont gene expression in Dendrophyllia sp., Eguchipsammia fistula, andRhizotrochus sp. sampled from the deep Red Sea. Bacterial community compositionwas analyzed via amplicon-based 16S surveys and cultured bacterial strains weresubjected to bioprospecting in order to gauge the pharmaceutical potential of coralassociatedmicrobes.Coral host transcriptome data suggest that coral can employ mitochondrialhypometabolism, anaerobic glycolysis, and surface cilia to enhance mass transportrates to manage the low oxygen and highly oligotrophic Red Sea waters. In themicrobial community associated with these corals, ribokinases and retron-typereverse transcriptases are abundantly expressed. In its first application to deep-seacoral associated microbial communities, 16S-based next-generation sequencingfound that a single operational taxonomic unit can comprise the majority ofsequence reads and that a large number of low abundance populations are present,which cannot be visualized with first generation sequencing. Bioactivity testing ofselected bacterial isolates was surveyed over 100 cytological parameters with high content screening, covering several major organelles and key proteins involved in avariety of signaling cascades. Some of these cytological profiles were similar tothose of several reference pharmacologically active compounds, which suggest thatthe bacteria isolates produce compounds with similar mechanisms of action as thereference compounds.The sum of this work offers several mechanisms by which Red Sea deep-sea coralscope with environmental conditions in which no other deep-sea corals have yet tobe reported. These deep-sea coral are associated with rich microbial communities,which produce molecules that induce bioactivity. The aggregate of this workprovides direction for future research of Red Sea deep-sea coral and highlights thepotential pharmacological benefit of conserving these species and their uniqueecosystem.