Planet of the Microbes

It’s not easy being invisible.

Even though they deal with some of the most interesting – and most powerful – creatures on the face of the Earth, microbiologists face a constant uphill battle bringing their subjects of study to the attention of average folks.

No wonder, then, that Institute on the Environment associate fellow Jeffrey Gralnick, a bacterial physiologist with the University of Minnesota’s Medical School and College of Biological Sciences BioTechnology Institute, knew he just had to stand up to the plate when he saw Momentum’s recent infographic, “Planet of the Insects.

The graphic provides a big-picture look at the number of known and estimated species in a dozen major taxonomic categories and was based on a 1992 study, the most recent available that covered the broad spectrum of living things. It includes bacteria, estimating the number of known species at 4,000 and the total number at about 400,000. What it does not include is an acknowledgment that since 1992, a lot has happened in the world of the invisible.

For one thing, taxonomists have recognized that the organisms we once knew as bacteria (or prokaryotes) are actually members of two distinct domains of life, bacteria and archaea, that together account for (by number of individuals) the bulk of living organisms alive on the planet today. For another, microbiologists have learned a lot more about what’s out there in the past 19 years. Current estimates, according to Gralnick, range from 7,000 to 90,000 known microbial species and 6 million or so actual species. And some of his colleagues think that’s still an underestimate.

In the spirit of the original article, Gralnick offers an E.O. Wilson quote of his own, excerpted from Wilson’s autobiography, Naturalist:

"If I could do it all over again, and relive my vision in the twenty-first century, I would be a microbial ecologist. Ten billion bacteria live in a gram of ordinary soil, a mere pinch held between thumb and forefinger. They represent thousands of species, almost none of which are known to science. Into that world I would go with the aid of modern microscopy and molecular analysis. I would cut my way through clonal forests sprawled across grains of sand, travel in an imagined submarine through drops of water proportionately the size of lakes, and track predators and prey in order to discover new life ways and alien food webs. All this, and I need venture no farther than ten paces outside my laboratory building. The jaguars, ants, and orchids would still occupy distant forests in all their splendor, but now they would be joined by an even stranger and vastly more complex living world virtually without end."

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