August 2, 2006 | David F. Coppedge

Bacteria Rule the World – Benevolently

We should love bacteria, not annihilate them.  Bacteria are our friends, according to Dianne K. Newman of Caltech:1

As a microbiologist, I’m appalled when I go to buy soap or dishwashing detergent, because these days it’s hard to find anything that doesn’t say ‘antibacterial’ on it…. It’s a commonly held fallacy that all bacteria are germs, but it’s been estimated that out of more than 30 million microbial species, only 70 are known to be pathogens.  That’s a trivial number.  The vast majority are actually doing remarkable things, both for the quality of our life and for the quality of the planet.

We couldn’t annihilate them, anyway, if we wanted to.  They are the most widespread and hardiest organisms on earth.  Maybe you heard on the news today that there are more bacteria on your cell phone than on a toilet seat.  Better to get used to it; they’re everywhere.
    The realization that bacteria rule the world began when Leeuwenhoek found more organisms on his teeth than men in a kingdom.  Newman continues:

Leeuwenhoek underestimated.  Not only do they exceed the number of men and women in a kingdom, they go far beyond that.  We have anywhere from 5 million to 50 million bacteria per square inch on our teeth, and over 700 microbial species living in our mouths.  Most of them are aiding us in our digestion—as are the 300 billion bacteria living in each gram of our colon.  The palms of our hands have between 5,000 and 50,000 organisms per square inch, although that’s nothing compared to the skin of our groin and armpit areas, which as at least 5 million per square inch.
    The grand total per person is about 70 trillion (70 x 1012), so we’re really walking vats of bacteria.  There are 10 times the number of microbial cells in an adult body than there are human cells, and the gut microbiome alone is estimated to contain more than a hundred times the number of genes that we have in our own genome—so there’s a remarkable amount of metabolic diversity living within us.  We shouldn’t be alarmed by this, however, because most of these bacteria are our friends.

If you are sufficiently grossed out by the revelation that you are a zoo, consider that the animals in a zoo represent just a tiny fraction of life on earth:

As well as living on and within animals, microbes live in plants, oceans, rivers, lakes, aquatic sediments, soils, subsoils, and air.  The total number of microbes on the planet has been estimated at 5 x 1030, which is an enormous number.  If they were all lined up end to end in a chain, it would stretch to the sun and back 200 x 1012 times.

A related article on BBC News noted the remarkable diversity of microbes.  “One litre of seawater can contain more than 20,000 different types of bacteria,” the article begins, suggesting that microbial diversity is much greater than imagined.
    Most of Dianne Newman’s delightful article is concerned with her Caltech team’s research into the amazing metabolic properties of certain bacteria that can live on rust as well as oxygen.  She talks about bacteria that can generate light, orient by magnetic fields, and help larger organisms in numerous ways.  Her colorful prose, unfortunately, is marred here and there by evolutionary stories that qualify for Stupid Evolution Quote of the Week:

  • They invented oxygenic photosynthesis…
  • Over the course of time, these types of cyanobacteria became engulfed by other organisms that then evolved into plants
  • …the chloroplast, is nothing more than an ancient cyanobacterium.
  • Moreover, we can only breathe this oxygen because our mitochondria—the little organelles in our cells that produce energy—are vestigial microorganisms descended from another ancient bacterium.
  • Microbes are very, very old.  They’ve been on our planet for at least 3.8 billion years, appearing just 800 million years after the planet formed.  for the first 1.6 billion years or so of their existence, they had the place to themselves, and it was only after the oxygenation of the air and oceans by the cyanobacteria that the forerunners of plants and animals came along.
  • The reason we find microbes almost everywhere we look is because, over the billions of years of Earth’s history they’ve been around, they’ve figured out how to be fantastic chemists.

Perhaps this is one of the reasons that Kansas school board member Connie Morris, who was just voted out of office (see yesterday’s entry), often described evolution as “a nice bedtime story.”


1Dianne K. Newman, “Bacteria Are Beautiful,” Caltech Engineering & Science (LXIX:2), Aug. 2006, pp. 8-15.

The parts of this article about observable, repeatable, testable science are great.  Newman is an engaging writer, and her team is doing important research into the metabolic workings of anaerobic bacteria.  This research might lead to rust-removing bioproducts and other blessings for mankind.  But how could she possibly know what happened 3.8 billion years ago?  The beneficial research owes nothing to the Darwinian bedtime story.  For treating evolutionary dogma as fact, we regret having to award SEQOTW to the author of an otherwise informative and delightful article.
    By the way, none of the criticism of antibacterial soap should be taken to mean that cleanliness and sanitation are unworthy goals.  It doesn’t take many of the 70 terrorist gangs to cause serious harm.  Everything in moderation.  Think about how few of the millions of microbial species are harmful to us.  If most are beneficial, it would almost suggest that something went wrong with the delinquent types.

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