St. Petersburg Coastal and Marine Science Center
Coral Microbial Ecology
Coral microbial ecology is the study of the relationship of coral-associated microorganisms to each other, the coral host, and to their environment. Just as we humans have beneficial bacteria living on our skin and in our intestines, corals also have co-habitating non-pathogenic (not disease-causing) microbes. These microbes include bacteria, archaea, and fungi—representing all three of the major domains of life.
What can we learn from studying coral microbial ecology? Why is it important? Coral reefs in the Caribbean have been in decline for several decades. One of the most visible causes is disease. Coral diseases are not well understood, but the few that have been characterized are all caused by microorganisms. In order to understand the diseased state, we must first understand the healthy state. Until now, coral biology studies have been limited to studies of the coral animal, the algal symbiont, or the interactions of the two. Coral microbial-ecology studies contribute a missing piece of information to the study of overall coral biology. It has been speculated that coral-associated bacteria benefit the coral by fixing nitrogen, breaking down waste products, and cycling basic nutrients back to the photosynthetic algal symbionts (zooxanthellae). Bacteria may also ward off other potentially harmful microbes by producing antibiotics or by just occupying the available space.
The coral microbial ecology group has an active research program identifying and characterizing the microbial associates of both tropical and cold-water (deep-sea) corals and their surrounding habitat. Current projects focus on coral disease dynamics, bacterial diversity, and using metagenomics to elucidate the functional roles of coral microbes.
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Our microarray study comparing the bacterial communities between healthy and white plague-like diseased corals in the Virgin Islands and Dry Tortugas has been published in the open access journal PLOS ONE. There were no apparent biogeographic differences between the diseases at the two locations (all diseased samples clustered together). Several Gram-positive groups were enriched in healthy samples (Actinobacteria and Firmicutes) and diseased samples (Corynebacteriaceae, Lachnospriaceae, and Streptococcaceae). Much previous coral disease work has used clone libraries or culturing, both of which seem to be methodologically biased toward recovery of Gram-negative bacteria, so the importance of these Gram-positive groups has been largely overlooked.
Stephanie Lawler has begun her graduate career this semester, beginning a master's degree jointly in the Kellogg lab at USGS and the Breitbart lab at University of South Florida. Lawler will be working with deep-sea gorgonians from Baltimore and Norfolk Canyons, characterizing their bacterial communities and also screening them for novel single-stranded DNA viruses.
Kellogg, C.A., Piceno, Y.M., Tom, L.M., DeSantis, T.Z., Gray, M.A., et al., 2013, Comparing Bacterial Community Composition between Healthy and White Plague-Like Disease States in Orbicella annularis Using PhyloChip™ G3 Microarrays: PLoS ONE 8(11): e79801. doi:10.1371/journal.pone.0079801.
Gray, M.A., Pratte, Z.A., and Kellogg, C.A., 2013, Comparison of DNA preservation methods for environmental bacterial community samples. FEMS Microbiology Ecology 83: 468-477. DOI: 10.1111/1574-6941.12008.
Galkiewicz, J.P., Stellick, S.H., Gray, M.A., and Kellogg, C.A., 2012, Cultured fungal associates from the deep-sea coral Lophelia pertusa. Deep-Sea Research I 67: 12-20.
Kellogg, C.A., Piceno, Y.M., Tom, L.M., DeSantis, T.Z., Zawada, D.G., and Andersen, G.L., 2012, PhyloChip™ microarray comparison of sampling methods used for coral microbial ecology. Journal of Microbiological Methods 88:103-109.
Galkiewicz, J.P., Pratte, Z.A., Gray, M.A., and Kellogg, C.A., 2011, Characterization of culturable bacteria isolated from the cold-water coral Lophelia pertusa. FEMS Microbiology Ecology 77:333-346.
Gray, M.A., Stone, R.P., McLaughlin, M.R., and Kellogg, C.A., 2011, Microbial consortia of gorgonian corals from the Aleutian islands. FEMS Microbiology Ecology 76: 109-120.
Kellogg, C.A., 2010, Enumeration of viruses and prokaryotes in deep-sea sediments and cold seeps of the Gulf of Mexico. Deep-Sea Research II 57: 2002-2007.
Olson, J.B., and Kellogg, C.A., 2010, Microbial ecology of corals, sponges, and algae in mesophotic coral environments. FEMS Microbiology Ecology 73: 17-30.
Kellogg, C.A., Lisle, J.T., and Galkiewicz, J.P., 2009, Culture-independent characterization of bacterial communities associated with the cold-water coral Lophelia pertusa in the northeastern Gulf of Mexico. Applied and Environmental Microbiology 75 (8): 2294-2303.
Diving into Coral Disease