Transient Shifts in Bacterial Communities Associated with the Temperate Gorgonian Paramuricea clavata in the Northwestern Mediterranean Sea

Abstract

BackgroundBacterial communities that are associated with tropical reef-forming corals are being increasingly recognized for their role in host physiology and health. However, little is known about the microbial diversity of the communities associated with temperate gorgonian corals, even though these communities are key structural components of the ecosystem. In the Northwestern Mediterranean Sea, gorgonians undergo recurrent mass mortalities, but the potential relationship between these events and the structure of the associated bacterial communities remains unexplored. Because microbial assemblages may contribute to the overall health and disease resistance of their host, a detailed baseline of the associated bacterial diversity is required to better understand the functioning of the gorgonian holobiont.Methodology/Principal FindingsThe bacterial diversity associated with the gorgonian Paramuricea clavata was determined using denaturing gradient gel electrophoresis, terminal-restriction fragment length polymorphism and the construction of clone libraries of the bacterial 16S ribosomal DNA. Three study sites were monitored for 4 years to assess the variability of communities associated with healthy colonies. Bacterial assemblages were highly dominated by one Hahellaceae-related ribotype and exhibited low diversity. While this pattern was mostly conserved through space and time, in summer 2007, a deep shift in microbiota structure toward increased bacterial diversity and the transient disappearance of Hahellaceae was observed.Conclusion/SignificanceThis is the first spatiotemporal study to investigate the bacterial diversity associated with a temperate shallow gorgonian. Our data revealed an established relationship between P. clavata and a specific bacterial group within the Oceanospirillales. These results suggest a potential symbiotic role of Hahellaceae in the host-microbe association, as recently suggested for tropical corals. However, a transient imbalance in bacterial associations can be tolerated by the holobiont without apparent symptoms of disease. The subsequent restoration of the Hahellaceae-dominated community is indicative of the specificity and resilience of the bacteria associated with the gorgonian host.

Late winter under ice pelagic microbial communities in the high Arctic Ocean and the impact of short-term exposure to elevated CO2levels

“…In fact, this suggests that there were a finite number of community outcomes from the starting community and stochastic processes were predominant. Containment facilitates experimental manipulation of growth conditions and is a valuable tool for understanding how living organisms and communities react to specific variables, it can also be used to select for species with traits that enable growth under specific conditions (Zobell, 1943; Ferguson et al, 1984; Massana et al, 2001). However, in nature plankton are subjected to advective flow and diffusion in addition to biological processes and interactions.…”

Crustose coralline algal species host distinct bacterial assemblages on their surfaces

“…Propionibacteria are known mostly for their role as commensal microbes or opportunistic pathogens on human skin and as fermenters in food making (Grice and Segre, 2011;Thierry et al, 2011). They have been found in marine samples (La Rivière et al, 2013;Li et al, 2014), and a BLAST search of these two OTUs reveals close matches (98% and 99%, respectively) to uncultured bacteria from deepsea sediments and ocean drilling cores (Table 2). Although their ecology in this environment remains largely unknown, two strains of Propionibacterium isolated from the coral Acropora digitifera exhibit broad-spectrum antibiotic activity (Nithyanand et al, 2011).…”

Endozoicomonas genomes reveal functional adaptation and plasticity in bacterial strains symbiotically associated with diverse marine hosts

“…for review14). These bacteria associate with a wide variety of marine hosts, including corals1516171819, and other cnidarians2021, sponges2223, gorgonians242526, molluscs2728, worms29, fish3031, and tunicates3233. Despite these associations with numerous hosts in oceans worldwide, the functional role of Endozoicomonas remains unclear.…”

“…Dimethylsulfoniopropionate (DMSP) breakdown has been suggested as a potential role2634, however, sequenced Endozoicomonas genomes lack DSMP metabolic pathways35. Endozoicomonas may also participate in a nutritional symbiosis, where the bacteria produce extracellular enzymes to degrade complex organic carbon sources that can then be used by the host25, as occurs with Oceanospirillales bacteria and deep-sea Osedax worms2. Another possibility is that Endozoicomonas interact with the algal symbiont Symbiodinium , either in a mutualistic or antagonistic relationship3637, although Endozoicomonas are also commonly found in organisms without photosymbionts38.…”