Are we human or are we bacteria?

NPR just reported on research done on the various kinds of bacteria that live on our body.  NPR is referring to new report from the lab of Julia Segre, Ph.D., at the National Human Genome Research Institute, NIH.   Here is the link to the article that NPR is talking about in PubMedCentral.   Here is the link to the page where the paper is published in Genome Research and is FREE to download.

OK.  So why is a scientist at the National Human Genome Research Institute doing research on bacteria?  Good question.  The answer is that there are so many bacteria living on us and inside of us, that the bacteria affect our bodies a great deal!  The bacteria eat and produce waste inside us and on our skin, they interact with our immune cells and our intestines.  Just like we have an extensive amount of cell to cell communication among the cells of our body, so are there extensive amounts of communication between bacteria and the cell of our body.  Sometimes bacteria alter the behavior of the cells of our body, in ways we used to think were only human-human cell interactions.   Additionally, the kind of bacteria that live in and on me may be different from the bacteria that live on someone else.  Could that make a difference?  It very well could!  Obesity or Crohn’s disease may be related to the bacteria in our gut.

First things first, how many bacteria live on us?  And how many different kinds of bacteria live on us?  Dr. Bonnie Bassler, of Princeton University, gives an estimate of these in her Ted talk, at the 2009 TED Conference.  Watch 0:55 through 2:30.  (The whole talk is fantastic, too!)   Number of human cells in the average adult = 1 trillion.  Number of bacteria cells in association with the average adult = 10 trillion.  Even more intriguing, is the number of genes that humans have is about 30,000.  How many different bacteria genes are associated with us?  300,000!

Link to Bonnie Bassler, PhD’s talk at the 2009 TED Conference.

OK, so there are SIGNIFICANT amounts of bacteria on our bodies, enough to affect us.  What are we going to do about it?  Well, we could follow the lead of scientists like Bonnie and Julia and start thinking of our associated bacteria genomes as part of our own!  And that means, of course, that we need to study them as much as we study ourselves.  And this is exactly what Julia Segre’s lab did.  Elizabeth Grice, Ph.D., is the first author of the paper, and she is the post doc in Dr. Julia Segre’s lab who lead the work of the paper.  Dr. Grice sampled 20 different locations on 10 different people, and found out which different kinds of organisms live in each spot.  Each location on our body provides a different climate.  Just like plants on the Earth, different bacteria grow better in a dry environment, while others grow better in a wet environment.  Elizabeth Grice, Ph.D. and her colleagues are out to find out who lives where.  This is basic research.  We don’t know yet how valuable this information will be.  But on Dr. Segre’s website you can see her research is clearly linked to disease and how to prevent it!

For an excellent, and easy to read, write up of Dr. Grice’s paper, you can go to an excellent science blog written by Ed Yong, “Not Exactly Rocket Science.”  Here is the NIH’s press release about the paper.

I hope this entry and links helps present the ideas of the world of bacteria, how much smaller and more numerous they are than us, as well as the idea that the things that that occur on the cellular level have big impact in our lives.

Posted in Biology, Chemistry
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