Clostridiales — Anaerococcus and Finegoldia

by Rob R. Dunn

Sometimes we just don’t know very much about the bacteria around or on us. Species of Anaerococcus, and Finegoldia are relatively closely related (both in the family Clostridiales). They are also, both individually and collectively, predictably abundant in belly buttons. Everything else we know about these microbes does not make a complete story; it does not even make an incomplete story. Instead it yields these bullets.

  • Many species of the bacteria genus Anaerococcus have been discovered in vaginas, the same for Finegoldia.
  • One species, Anaerococcus senegalensis, is known from samples of human feces in Senegal.
  • Anaerococcus species are able to use amino acids as energy sources. As waste they produce butyrate, a small fatty acid.
  • Finegoldia species are anaerobic. They live without oxygen. Finegoldia species live in communal chains of cells. They ferment sugars and produce, as a result of that fermentation, acetic acid. More rarely, Finegoldia use amino acids for energy and when they do produce ammonia as a by-product. Finegoldia is known to be able to use a special protein (Protein L) to bind human immunoglobulin molecules onto its surface. In doing so, it camouflages itself, but most of the time Finegoldia does no harm and so it is not quite a wolf in sheep’s clothing but maybe, rather, a sheep in sheep’s clothing. Wait, that is one step to far. It is just a bacterium in our clothing. Oh, I can’t get this right. You get the idea.
  • In addition to vaginas and feces in Senegal, the other place Anaerococcus have been found is in fermented sausages.
  • You probably want me to be able to make meaning of these bits of information and explain why it is that you have these species living in your belly button. I wish I could too.

About the Author

Rob Dunn is an evolutionary biologist and writer. His research focuses on understanding the ecology and evolution of the species humans interact with every day but pay relatively little attention to. Much of the science he does is public science in which citizens are involved in data collection, crafting hypothesis and even conducting analyses. His most recent book, The Wild Life of Our Bodies tells the stories of the consequences of our changing relationships with other species for our health and well-being. His next book considers the story of the human heart and its history, biology, evolution and problems. Dunn’s magazine articles appear often in National Geographic, Smithsonian Magazine, Scientific American Magazine, and many other magazines. See more about Rob’s writing at See more about his science at