A ubiquitous subcuticular bacterial symbiont of a coral predator, the crown-of-thorns starfish, in the Indo-Pacific

Microbiome

Gal Eyal¹  Hugh Sweatman²  Sen-Lin Tang³  Atsushi Toyoda⁴  Yasuhiro Gotoh⁵  Tetsuya Hayashi⁵  Yoshitoshi Ogura⁵  Nina Yasuda⁶  Yukihiro Higashimura⁶  Naohisa Wada⁶  Omri Bronstein⁷  Zac Forsman⁸  Nalinee Thongtham⁹  Rei Kajitani^1,10  Dai Yoshimura^1,10  Takehiko Itoh^1,10  Hideaki Yuasa^1,10 

[1] ARC Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland;Australian Institute of Marine Science;Biodiversity Research Center, Academia Sinica;Center for Information Biology, National Institute of Genetics;Department of Bacteriology, Faculty of Medical Sciences, Kyushu University;Faculty of Agriculture, University of Miyazaki;George S. Wise Faculty of Life Sciences, School of Zoology, Tel Aviv University;Hawai’i Institute of Marine Biology, School of Ocean & Earth Sciences & Technology, University of Hawai’i at Mānoa;Phuket Marine Biological Center;School of Life Science and Technology, Department of Life Science and Technology, Tokyo Institute of Technology;

关键词: Crown-of-thorns starfish;    Subcuticular bacteria;    Marine spirochetes;   

DOI  :  10.1186/s40168-020-00880-3

来源: DOAJ

【 摘 要 】

Abstract Background Population outbreaks of the crown-of-thorns starfish (Acanthaster planci sensu lato; COTS), a primary predator of reef-building corals in the Indo-Pacific Ocean, are a major threat to coral reefs. While biological and ecological knowledge of COTS has been accumulating since the 1960s, little is known about its associated bacteria. The aim of this study was to provide fundamental information on the dominant COTS-associated bacteria through a multifaceted molecular approach. Methods A total of 205 COTS individuals from 17 locations throughout the Indo-Pacific Ocean were examined for the presence of COTS-associated bacteria. We conducted 16S rRNA metabarcoding of COTS to determine the bacterial profiles of different parts of the body and generated a full-length 16S rRNA gene sequence from a single dominant bacterium, which we designated COTS27. We performed phylogenetic analysis to determine the taxonomy, screening of COTS27 across the Indo-Pacific, FISH to visualize it within the COTS tissues, and reconstruction of the bacterial genome from the hologenome sequence data. Results We discovered that a single bacterium exists at high densities in the subcuticular space in COTS forming a biofilm-like structure between the cuticle and the epidermis. COTS27 belongs to a clade that presumably represents a distinct order (so-called marine spirochetes) in the phylum Spirochaetes and is universally present in COTS throughout the Indo-Pacific Ocean. The reconstructed genome of COTS27 includes some genetic traits that are probably linked to adaptation to marine environments and evolution as an extracellular endosymbiont in subcuticular spaces. Conclusions COTS27 can be found in three allopatric COTS species, ranging from the northern Red Sea to the Pacific, implying that the symbiotic relationship arose before the speciation events (approximately 2 million years ago). The universal association of COTS27 with COTS and nearly mono-specific association at least with the Indo-Pacific COTS provides a useful model system for studying symbiont-host interactions in marine invertebrates and may have applications for coral reef conservation. Video Abstract

【 授权许可】

Unknown