Abstract
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.
Funder
KAKENHI
KAKENHI Grant-in-aid for Young Scientists
the Environment Research and Technology Development Fund
Academia Sinica
KAKENHI Grant-in-Aid for JSPS Fellows
European Union’s Horizon 2020 research and innovation programme under MSCA
Publisher
Springer Science and Business Media LLC
Subject
Microbiology (medical),Microbiology
Reference49 articles.
1. Spalding MD, Ravilious C, Green EP. World atlas of coral reefs. Prepared at the UNEP World Conservation Monitoring Centre. Univ Calif Berkeley EEUULinks. 2001;.
2. Wilkinson C. Status of coral reefs of the world: 2004. Australian Institute of Marine Science; 2004.
3. Moran P, Bradbury R. The crown-of-thorns starfish controversy. Search. 1989;20:3–6.
4. Birkeland C, Lucas J. Acanthaster planci: major management problem of coral reefs. CRC Press; 1990.
5. Pratchett MS, Caballes CF, Sweatman JAR-P& HPA. Limits to understanding and managing outbreaks of crown-of-thorns starfish (Acanthaster spp.). Oceanogr Mar Biol. 2014;52:133–200.
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献