Culture-Independent Characterization of Bacterial Communities Associated with the Cold-Water Coral Lophelia pertusa in the Northeastern Gulf of Mexico

Abstract

Bacteria are recognized as an important part of the total biology of shallow-water corals. Studies of shallow-water corals suggest that associated bacteria may benefit the corals by cycling carbon, fixing nitrogen, chelating iron, and producing antibiotics that protect the coral from other microbes. Cold-water or deep-sea corals have a fundamentally different ecology due to their adaptation to cold, dark, high-pressure environments and as such have novel microbiota. The goal of this study was to characterize the microbial associates of Lophelia pertusa in the northeastern Gulf of Mexico. This is the first study to collect the coral samples in individual insulated containers and to preserve coral samples at depth in an effort to minimize thermal shock and evaluate the effects of environmental gradients on the microbial diversity of samples. Molecular analysis of bacterial diversity showed a marked difference between the two study sites, Viosca Knoll 906/862 (VK906/ 862) and Viosca Knoll 826 (VK826). The bacterial communities from VK826 were dominated by a variety of unknown mycoplasmal members of the Tenericutes and Bacteroidetes, whereas the libraries from VK906/862 were dominated by members of the Proteobacteria. In addition to novel sequences, the 16S rRNA gene clone libraries revealed many bacterial sequences in common between Gulf of Mexico Lophelia corals and Norwegian fjord Lophelia corals, as well as shallow-water corals. Two Lophelia-specific bacterial groups were identified: a cluster of gammaproteobacteria related to sulfide-oxidizing gill symbionts of seep clams and a group of Mycoplasma spp. The presence of these groups in both Gulf and Norwegian Lophelia corals indicates that in spite of the geographic heterogeneity observed in Lophelia-associated bacterial communities, there are Lophelia-specific microbes.Cold-water and deep-sea corals have become a topic of interest due to conservation concerns over the impacts of trawling, exploration for oil and gas, and climate change (51,52). Although the existence of these corals has been known since the 1800s, our knowledge of their distribution, ecology, and biology is limited due to the technical difficulties of studying them. Lophelia pertusa is a globally distributed cold-water scleractinian coral (53). In the Gulf of Mexico, Lophelia reefs occur primarily along the continental shelf break (300-to 500-m depth), providing an important complex habitat for a wide variety of fishes, crustaceans, and other invertebrates living below the photic zone (48).The microbial ecology of cold-water corals in deep water is fundamentally different from that of shallow-water corals due to the ambient environmental parameters (e.g., darkness, low temperature, and increased pressure) and the absence of symbiotic zooxanthellae. A few studies have begun to address the microbial associates of deep-sea corals, focusing on octocorals (9, 44) and on L. pertusa (27,41,42,57,72). To date, all the Lophelia studies have been conducted on the eastern side of the Atlantic: the Mediterr...

Microbial degradation of cold-water coral-derived organic matter: potential implication for organic C cycling in the water column above Tisler Reef

“…This can be explained by mucus-specific microbial communities as described for warm-water corals (Ritchie & Smith 2004, Ritchie 2006, Kooperman et al 2007, Allers et al 2008. Such an explanation is also supported for cold-water corals by the studies of Neulinger et al (2008) and Kellogg et al (2009), which indicate that L. pertusa-specific microbial communities exist. Furthermore, the study of Schöttner et al (2009), showed that different L. pertusa-and Madrepora oculata-generated habitats, including the coral-derived mucus surface layer, offer niches for specific microbial communities.…”

Composition of Bacterial Communities Associated with Aurelia aurita Changes with Compartment, Life Stage, and Population

“…Mollicutes are widespread commensals or pathogens of humans, mammals, reptiles, fish, plants, and other arthropods (reviewed in reference 67) and have also been reported to be associated with different invertebrates, e.g., earthworms (12), isopods (11), oysters (68,69), crustaceans (10), bryozoans (70), ctenophores (63,71), and also cnidarians (72)(73)(74). Parasitic, commensal, and mutualistic endosymbioses are widely distributed among invertebrate taxa and have arguably played a major role in the evolution of several invertebrate families, classes, and phyla (75).…”

Distinct Bacterial Microbiomes Associate with the Deep-Sea Coral Eguchipsammia fistula from the Red Sea and from Aquaria Settings

“…However, mainly due to their limited accessibility, the knowledge on deep-sea corals is still scarce, especially in regard to their associated microbial communities. Few studies characterized deep-sea coral associated bacterial communities, focusing mainly on octocorals (Penn et al, 2006;Gray et al, 2011;Kellogg et al, 2016;Lawler et al, 2016) and two reef-building scleractinian corals, namely Lophelia pertusa and Madrepora oculata (Yakimov et al, 2006;Neulinger et al, 2008Neulinger et al, , 2009Hansson et al, 2009;Kellogg et al, 2009Kellogg et al, , 2017Schöttner et al, 2009Schöttner et al, , 2012Galkiewicz et al, 2011;Emblem et al, 2012;van Bleijswijk et al, 2015;Meistertzheim et al, 2016). Findings include species-specific microbiomes, but also considerable spatial and temporal variations.…”