Dominant coral-associated bacterium, Endoziocomonas acroporae, can produce climate-cooling gas dimethylsulfide A research team lead by Dr. Sen-Lin Tang at Biodiversity Research Center, Academia Sinica, in collaboration with National Taiwan University, National Sun Yat- sen University, and National Kaohsiung University of Science and Technology, has discovered a bacterium: Endozoicomonas acroporae, which is commonly found in healthy corals, encodes a gene (dddD) in their genome. The presence of the dddD gene can help bacteria metabolize the climate-cooling gas precursor, Dimethylsulfoniopropionate (DMSP). Experiments conducted in this study also confirm the bacteria have the ability to metabolite DMSP and produce the climate-cooling gas, Dimethylsulfide (DMS). This study provides groundbreaking evidence for the ecological role of E. acroporae in their coral host. The results from the study have been published in the journal, The ISME Journal, on February 13th, 2020. (Fig. 1.) Fig. 1. Illustration of E. acroporae-mediated DMSP degradation DMSP is one of the most abundant organosulfur in the world. Besides, it is also an important compound that participates in the global sulfur cycle. It’s decomposed product DMS is a famous climate-cooling gas, which can facilitate cloud formation and thus aid in cooling the temperature. DMSP is majorly produced by coral reefs, phytoplankton, and bacteria. The global production of this compound can reach one billion tons each year. DMSP from corals is not only a protectant against stress (osmotic 1 and oxidative) but also an attractant for certain coral-associated bacterial groups. One of the most dominant and widely studied coral-associated bacterial groups belongs to the genus Endozoicomonas. The genus’ ecological functions have longe remained cryptic, but it has been hypothesized to play an active role in coral-sulfur metabolism, effectively metabolizing DMSP to DMS. However, none of the sequenced genomes from Endozoicomonas isolates of corals or other marine invertebrates harbor the gene(s) for this process. In this study, we used cultures of the new species E. acroporae from coral Acropora sp. and assembled high-quality draft genomes of its two new strains along with an earlier published type strain E. acroporae Acr-14T genome. Using a comparative genomics approach, we identified a homolog of a DMSP acyl CoA- transferase/lyase gene, dddD, in all the E. acroporae strains. This is the first report to identify DMSP metabolism-related genes in this bacteria genus. The functional activity of the dddD gene homolog was confirmed with RT-qPCR and gas chromatography. Furthermore, we present an arrangement of genes in an operon-like manner that links DMSP metabolism to the central carbon cycle, and profiled the abundance of E. acroporae across the Pacific Ocean, and identified that this species has a broad host range and distribution. The results indicate that this genus of bacteria may have an important ecological role in coral reefs DMSP metabolism and sulfur cycle. This study provides the first genomic and functional evidence that Endozoicomonas may participate in the coral sulfur cycle, putting an end to uncertainty around this genus’ place in the coral ecosystem. (Fig. 2.) Fig. 2. Dr. Sen-Lin Tang’s research team. 2 This study was funded by Academia Sinica and the Ministry of Science and Technology. The first author Mr. Kshitij Tandon is a Ph.D. Candidate of the TIGP Bioinformatics of Academia Sinica in collaboration with National Tsing Hua University. The article can be accessed from: https://www.nature.com/articles/s41396-020- 0610-x 3 .