TWENTY-FIFTH ANNUAL EASTERN FISH HEALTH WORKSHOP MARCH 10-13, 2000          Characterization Of Beggiatoa Spp. From The Black Band Disease Microbial Consortium     Shay Viehman and Laurie Richardson   Department of Biological Sciences, Florida International University, Miami FL 33199       Black band disease of scleractinian corals consists of a highly organized microbial consortium that generates and maintains an active sulfur cycle as it actively destroys coral tissue. The consortium is biologically and chemically analogous to non-pathogenic microbial mat communities found in many benthic, illuminated, sulfide-rich aquatic environments. Dominant members of the black band consortium include the cyanobacterium Phormidium corallyticum, the sulfide-oxidizing bacterium Beggiatoa spp., the sulfate-reducing bacterium Desulfovibrio spp., and other microbes.  Of these, the oxygenic cyanobacterium together with Beggiatoa and Desulfovibrio appear to be responsible for producing and sustaining vertical gradients of oxygen and sulfide within the 1mm thick band.  We are investigating the physiology of the black band disease consortial members in the laboratory to define the functional roles of each of these within the pathogenic black band community.   Part of this research is focused on the ecological physiology of the black band Beggiatoa spp. Members of the genus Beggiatoa are typically located at sulfide-oxygen interface environments, such as in sediments, microbial mats, and hydrothermal vents.  Beggiatoa spp. from the black band disease consortium are in culture in the laboratory, and are maintained on sulfide gradient media as well as on plates in a micro-aerobic (70-90% N2) environment.  Single filament isolation technique is being applied to achieve a pure culture.  The (non-axenic) black band Beggiatoa spp. grow in the laboratory on sulfide and thiosulfate (electron donors in sulfur oxidation), and also on acetate and thiosulfate.  This is in agreement with the metabolism of other known marine strains of Beggiatoa which are obligate or facultative chemolithoautotrophs. The organic compounds presumably available from lysing coral tissue under the black band may be able to support heterotrophic growth as well as the observed autotrophic growth of Beggiatoa.   Within black band disease, Beggiatoa spp. also displays unique motility patterns that could be important in the horizontal migration of the disease across coral tissue.  Both the physiology and motility research will enhance our understanding of black band disease etiology and its role in the natural coral reef environment.     Return to 25th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page