Shenzhen Research Institute and Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Sci Rep. 2017 Aug 24;7(1):9320. doi: 10.1038/s41598-017-09032-4.
Coral reefs are ecologically significant habitats. Coral-algal symbiosis confers ecological success on coral reefs and coral-microbial symbiosis is also vital to coral reefs. However, current understanding of coral-microbial symbiosis on a genomic scale is largely unknown. Here we report a potential microbial symbiont in corals revealed by metagenomics-based genomic study. Microbial cells in coral were enriched for metagenomic analysis and a high-quality draft genome of "Candidatus Prosthecochloris korallensis" was recovered by metagenome assembly and genome binning. Phylogenetic analysis shows "Ca. P. korallensis" belongs to the Prosthecochloris clade and is clustered with two Prosthecochloris clones derived from Caribbean corals. Genomic analysis reveals "Ca. P. korallensis" has potentially important ecological functions including anoxygenic photosynthesis, carbon fixation via the reductive tricarboxylic acid (rTCA) cycle, nitrogen fixation, and sulfur oxidization. Core metabolic pathway analysis suggests "Ca. P. korallensis" is a green sulfur bacterium capable of photoautotrophy or mixotrophy. Potential host-microbial interaction reveals a symbiotic relationship: "Ca. P. korallensis" might provide organic and nitrogenous nutrients to its host and detoxify sulfide for the host; the host might provide "Ca. P. korallensis" with an anaerobic environment for survival, carbon dioxide and acetate for growth, and hydrogen sulfide as an electron donor for photosynthesis.
珊瑚礁是具有重要生态意义的栖息地。珊瑚-藻类共生赋予了珊瑚礁生态上的成功，而珊瑚-微生物共生对珊瑚礁也至关重要。然而，目前对珊瑚-微生物共生在基因组层面上的理解在很大程度上仍是未知的。在这里，我们通过基于宏基因组学的基因组研究报告了一种珊瑚中的潜在微生物共生体。从珊瑚中富集微生物细胞进行宏基因组分析，并通过宏基因组组装和基因组分箱获得了高质量的“珊瑚假菌属（Ca. Prosthecochloris）”候选菌株的基因组草图。系统发育分析表明，“Ca. P. korallensis”属于假菌属（Prosthecochloris）分支，与来源于加勒比珊瑚的两个假菌属克隆聚类在一起。基因组分析揭示“Ca. P. korallensis”具有潜在的重要生态功能，包括不产氧光合作用、通过还原性三羧酸（rTCA）循环进行碳固定、固氮和硫氧化。核心代谢途径分析表明“Ca. P. korallensis”是一种绿色硫细菌，能够进行自养或混合营养生长。潜在的宿主-微生物相互作用揭示了一种共生关系：“Ca. P. korallensis”可能为其宿主提供有机和含氮营养物质，并为宿主解毒硫化物；宿主可能为“Ca. P. korallensis”提供生存所需的厌氧环境、二氧化碳和乙酸盐以供生长，并提供硫化氢作为光合作用的电子供体。
