Genomic Insight into the Host–Endosymbiont Relationship of Endozoicomonas montiporae CL-33T with its Coral Host

Abstract

The bacterial genus Endozoicomonas was commonly detected in healthy corals in many coral-associated bacteria studies in the past decade. Although, it is likely to be a core member of coral microbiota, little is known about its ecological roles. To decipher potential interactions between bacteria and their coral hosts, we sequenced and investigated the first culturable endozoicomonal bacterium from coral, the E. montiporae CL-33T. Its genome had potential sign of ongoing genome erosion and gene exchange with its host. Testosterone degradation and type III secretion system are commonly present in Endozoicomonas and may have roles to recognize and deliver effectors to their hosts. Moreover, genes of eukaryotic ephrin ligand B2 are present in its genome; presumably, this bacterium could move into coral cells via endocytosis after binding to coral's Eph receptors. In addition, 7,8-dihydro-8-oxoguanine triphosphatase and isocitrate lyase are possible type III secretion effectors that might help coral to prevent mitochondrial dysfunction and promote gluconeogenesis, especially under stress conditions. Based on all these findings, we inferred that E. montiporae was a facultative endosymbiont that can recognize, translocate, communicate and modulate its coral host.

Dominance of Endozoicomonas bacteria throughout coral bleaching and mortality suggests structural inflexibility of the Pocillopora verrucosa microbiome

“…More generally, Endozoicomonas are commonly assumed to provide an important role in coral holobiont functioning due to their widespread prevalence and high abundance in many coral species (Bayer et al., 2013; Gignoux‐Wolfsohn, Aronson, & Vollmer, 2017; Glasl et al., 2016; Jessen et al., 2013; Meyer, Gunasekera, Scott, Paul, & Teplitski, 2016; Neave et al., 2016; Neave, Rachmawati, et al., 2017) and apparent metabolic versatility (Ding, Shiu, Chen, Chiang, & Tang, 2016; Hyun et al., 2014; Neave, Michell, et al., 2017; Yang et al., 2010). Further, reductions in the abundance of Endozoicomonas in stressed, diseased, or bleached corals are reported in a number of studies, suggesting that pervasive abundance of Endozoicomonas might be an indicator of habitat suitability (Bourne et al., 2008; Cárdenas et al., 2012; Gignoux‐Wolfsohn et al., 2017; Meyer et al., 2016; Morrow et al., 2014; Roder et al., 2015; Röthig et al., 2016; Ziegler et al., 2016).…”

Intergenerational effects of macroalgae on a reef coral: major declines in larval survival but subtle changes in microbiomes

“…In support of this hypothesis, we found similarly high relative abundances (>80%) of Endozoicimonaceae bacteria in adult P. damicornis coral from both healthy and degraded reefs. Recent evidence suggests that these bacteria are functionally important members of the healthy coral holobiont in multiple coral species (Meyer et al 2014, Lee et al 2015, Ding et al 2016, Neave et al 2016), including P. damicornis (Bayer et al 2013). We also detected similar abundances of Endozoicimonacaeae (1–12%) on larvae from both the MPA and fished area, adding further support for the hypothesized importance of these bacteria in P. damicornis persistence.…”

Responses of Coral-Associated Bacterial Communities to Local and Global Stressors

“…within the coral tissues, suggesting an intimate association with coral hosts Neave et al, 2016). Additionally, the first cultivable Endozoicomonas from corals suggests Endozoicomonas montiporae CL-33 helps corals under stress through preventing mitochondrial dysfunction and promoting gluconeogenesis (Ding et al, 2016). Additionally, researchers have proposed that Endozoicomonas plays a role in sulfur cycling (Raina et al, 2009), nutritional symbiosis (La Rivière et al, 2013) and protecting Symbiodinium from bleaching pathogens (Pantos et al, 2015).…”