Editor's Letter: Microbial ecosystems

last updated 8 January 2015

As we humans fret over how recklessly we dominate nature, I hear the sound of microbes chuckling. What calls this to mind this week is their deadly infiltration into our food supply (see Talking Points). But even when microorganisms don’t make headlines, they quietly steer our fates. Colonies of bacteria can be found in our intestines and on our mucus membranes, our skin, and virtually every inch of our bodies, which is why the National Institutes of Health is funding a major research initiative to map “the human microbiome”—the DNA sequences of our invisible passengers. Our bodies contain 10 times more microbes than human cells, and we’re just beginning to grasp what a massive influence they could have on our health. As one biologist friend of mine puts it, “We’re essentially a microbial ecosystem.”

The same could be said of the earth itself. Scientists now say that even raindrops form around microbes, and some bacteria appear to have evolved specifically to promote precipitation. Viewed from this perspective, the water cycle on which so much life depends may be primarily a means for bacteria to get from one plant to another. I was recently reminded of the might of microorganisms when I got food poisoning from a sausage-borne pathogen on a slice of pizza; after I stopped vomiting, I could only agree with the microbes’ stern judgment that I should be eating better. On the other hand, health-conscious vegetarians are now becoming deathly ill because of beasties hidden in organic bean sprouts. Either way, it seems, we can’t win. Or as Louis Pasteur, who knew his germs, said, “It is the microbes that will have the last word.”