Novel Microbial Diversity and Functional Potential in the Marine Mammal Oral Microbiome Natasha K. Dudek,1 Christine L. Sun,2,3 David Burstein,4 Rose S. Kantor,5 Daniela S. Aliaga Goltsman,2,3 Elisabeth M. Bik,2,8 Brian C. Thomas,4 Jillian F. Banfield,4,6 and David A. Relman2,3,7,9, * 1Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA 2Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA 3Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA 4Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA 5Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA 6Earth and Environmental Science, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA 7Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA 8Present address: uBiome, San Francisco, CA 94105, USA 9Lead Contact *Correspondence:
[email protected] Summary The vast majority of bacterial diversity lies within phylum-level lineages called “candidate phyla,” which lack isolated representatives and are poorly understood. These bacteria are surprisingly abundant in the oral cavity of marine mammals. We employed a genome-resolved metagenomic approach to recover and characterize genomes and functional potential from microbes in the oral gingival sulcus of two bottlenose dolphins (Tursiops truncatus). We detected organisms from 24 known bacterial phyla and one archaeal phylum. We also recovered genomes from two deep-branching, previously uncharacterized phylum-level lineages (here named “Candidatus Delphibacteria” and “Candidatus Fertabacteria”). The Delphibacteria lineage is found in both managed and wild dolphins; its metabolic profile suggests a capacity for denitrification and a possible role in dolphin health.