1. ¹Department of Chemistry and Biochemistry, Center of Excellence in Biomedical and Marine Biotechnology, Florida Atlantic University, Boca Raton, FL, USA
2. ²Center for Ocean Exploration, Harbor Branch Oceanographic Institution, Fort Pierce, FL, USA
3. ³Department of Chemistry, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
4. ⁴Department of Biomedical Sciences, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada

Correspondence: RG Kerr, Department of Chemistry, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3. E-mail: rkerr@upei.ca

⁵These authors have made equal contributions to this publication.

Received 11 June 2007; Revised 27 August 2007; Published online 18 October 2007.

Abstract

This study examined the symbiotic microbiota of the hexacoral Cirrhipathes lutkeni using traditional plate culture, fluorescence in situ hybridization (FISH) and 16S rDNA characterization. FISH counts for the whole coral (holobiont) showed a major presence of -Proteobacteria (22%) and Actinobacteria (19%), followed by -Proteobacteria (14%), Firmicutes (9%), Cytophaga-Flavobacterium (7%), -Proteobacteria (6%) and Chloroflexi (2%). In contrast to the diversity observed by FISH, plate cultures were found to be selective for -Proteobacteria (22 cultures) with the exception of an Actinobacterium. The methods employed in this study detected 76% of all microbes estimated by DAPI staining of C. lutkeni homogenates. The absence of zooxanthellae in this particular hexacoral was confirmed by PCR and spectrophotometry using fresh tissue isolated from the holobiont. This is the first study describing the microbial associations of shallow-water hexacorallia, which opens further insight into coral microbial ecology and may enhance the search for novel natural products in the near future.