[M-IS21] Chemosynthetic community and mud volcano: biology, geochemistry, and geophysics of fluid discharge

[MIS21-05] The minor-yet-crucial roles of gut microbiomes in a deep-sea hydrothermal vent snail

*Yi YANG^1,2, Jin SUN^1,3, Chong CHEN⁴, Yadong ZHOU⁵, Cindy Lee Van Dover⁶, Chunsheng WANG^5,7, Jian-Wen QIU^2,8, Pei-Yuan QIAN^1,2 (1.Department of Ocean Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong, China, 2.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China, 3.Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China, 4.X-STAR, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan, 5.Laboratory of Marine Ecosystem and Biogeochemistry, Second Institute of Oceanography, State Oceanic Administration, Hangzhou, China, 6.Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC, United States, 7.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou, China, 8.Department of Biology, Hong Kong Baptist University, Hong Kong, China)

Keywords:Deep-sea vent, Provannid snail, Gut, Microbiome, Metagenome, Metatranscriptome

Eukaryotes often exhibit a complex symbiotic relationship with gut microbes to attain better use of the available resources. Many animals endemic to deep-sea chemosynthetic ecosystems host chemoautotrophic bacteria endocellularly, and are thought to rely entirely on these symbionts for energy and nutrition. The provannid snail Alviniconcha marisindica hosts a Campylobacterial endosymbiont in its gill, but unlike many other chemosymbiotic animals, its gut is reduced but still functional. Here, we show through metagenomic and metatranscriptomic analyses that the gut microbiome of A. marisindica plays key nutritional and metabolic roles. The diversity of A. marisindica gut microbiota is comparable to that of the snails without symbionts but its composition and relative abundance differed from these snails. The relative abundance of microbial composition remains similar among three A. marisindica and their microbial community shows significant multi-taxa associations, suggesting a long-term association. Functional profiling of the gut microbiome reveals thousands of additional genes for the holobiont to cope with the shortage of amino acids, vitamins, and lipids, as well as the accumulation of metabolic waste and the maintenance of homeostasis. These microbes have the potential to form the protective slime capsule to protect themselves from the host’s immune system, thereby contributing to their survival and development. Our findings advance the understanding of how deep-sea chemosymbiotic animals obtain available resources through considering an additional contribution of gut microbiota. The widespread less-abundant gut microbiota is potential to help hosts survive and thrift in extreme environments.