The pseudocolonial coral Lophelia pertusa (Scleractinia, Caryophylliidae) is a eurybathic, stenothermal cosmopolitancold-water species. It occurs in two color varieties, white and red. L. pertusa builds vast cold-water coral reefsalong the continental margins, which are among the most diverse deep-sea habitats. Microbiology of L. pertusa hasbeen in scientific focus for only a few years, but the question of whether the coral holds a host-specific bacterialcommunity has not been finally answered. Bacteria on coral samples from the Trondheimsfjord (Norway) werecharacterized by the culture-independent 16S rRNA gene-based techniques terminal restriction fragment lengthpolymorphism and sequence analysis. L. pertusa revealed a high microbial richness. Clone sequences were dominatedby members of the Alpha- and Gammaproteobacteria. Other abundant taxa were Bacteroidetes, Actinobacteria,Verrucomicrobia, Firmicutes, and Planctomycetes. The bacterial community of L. pertusa not only differed conspicuouslyfrom that of the environment but also varied with both the location and color variety of its host. Therefore,the microbial colonization cannot be termed specific sensu stricto. However, similarities to other coral-bacteriumassociations suggest the existence of cold-water coral-specific bacterial groups sensu lato. L. pertusa-associatedbacteria appear to play a significant role in the nutrition of their host by degradation of sulfur compounds, cellulose,chitin, and end products of the corals anaerobic metabolism. Some coral-associated microbes were regarded asopportunistic pathogens. Dominance of mixotrophic members of the Rhodobacteraceae in white L. pertusa couldexplain the wider dispersal of this phenotype by supplementary nutrition.