Metagenomic analysis reveals a green sulfur bacterium as a potential coral symbiont

• Published in: Scientific reports 2017-08, Vol.7 (1), p.9320-11, Article 9320
• Main Authors: Cai, Lin, Zhou, Guowei, Tian, Ren-Mao, Tong, Haoya, Zhang, Weipeng, Sun, Jin, Ding, Wei, Wong, Yue Him, Xie, James Y., Qiu, Jian-Wen, Liu, Sheng, Huang, Hui, Qian, Pei-Yuan
• Format: Article
• Language: English
• Subjects: 45/22; 45/23; 45/29; 45/43; 45/77; 631/158/855; 631/326/41/2535; Acetic acid; Algae; Animals; Anthozoa - microbiology; Candidatus Prosthecochloris korallensis; Carbon dioxide; Carbon fixation; Caribbean Region; Chlorobi - classification; Chlorobi - genetics; Chlorobi - physiology; Cluster Analysis; Computational Biology; Coral reefs; Corals; Ecological function; Genomes; Genomic analysis; Genomics; Green sulfur bacteria; Humanities and Social Sciences; Hydrogen sulfide; Metabolic Networks and Pathways - genetics; Metagenomics; Mixotrophy; multidisciplinary; Nitrogen fixation; Nutrients; Photoautotrophy; Photosynthesis; Phylogeny; Science; Science (multidisciplinary); Sulfides; Sulfur; Symbiosis; Tricarboxylic acid cycle; Whole Genome Sequencing
• ISSN: 2045-2322; 2045-2322
• 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.