Isolates the genes encoding the small subunit ribosomal RNA from two morphotypes and uses them in a phylogenetic analysis to resolve the nature of the symbiosis of the large, morphologically peculiar microorganism Epulopiscium fishelsoni. Acanthurus nigrofuscus; Phylogenetic trees relating the surgeonfish symbionts to other bacteria; In situ hybridization of gut contents with symbiont-specific, fluorescein labelled oligonucleotides; More.