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Monday, November 30, 2015
I'm looking at myself and the world differently these days, after taking a course on creatures I can see only through a microscope. The view is both awe-inspiring and frightening.
Fears first. University of Illinois researcher Claudia Reich says "perfect storm" conditions exist for awful things to happen to humans because of rogue microbes. In an Osher Lifelong Learning Institute course on "The Microbial World," Reich said a combination of weakened gut flora in humans, antibiotic-resistant microbes, and drug industry economics spells trouble ahead.
The healthy human gut is host to a wide variety of bacteria, but they can run wild if the delicate balance between host and guests is upset. Gut samples show that those of us who eat a typical Western diet have the least diverse microbial gut flora in the world. In such an environment, normally minor residents like Clostridium difficile and Escherichia coli can run amok and make us sick or even kill us, Reich said.
Diet and modern medicine help create converging risks when human patients are over-treated with antibiotics and meat and poultry are routinely dosed with them to boost weight gain. The result is dangerous, possibly lethal resistant strains of bacteria. While doctors are thinking twice about routinely prescribing antibiotics, the food industry continues to dose cattle, pigs, and especially poultry, a practice Reich bluntly characterized as "stupid." In a recent year, she said, 7.7 million pounds of antibiotics were used in human medicine, 29.9 million pounds in meat and poultry.
Microbes have always contained genes for antibiotic resistance, but with today's overuse of drugs we're selecting for them, and have to race to keep up. It costs about $200 million and takes 10 years to develop a new antibiotic, Reich said. Resistant strains appear in about a year, and after two years the drug is obsolete. As a result, development of new antibiotics has virtually ground to a halt in private industry, she said.
Ending the course on a positive note, Reich gave us something to hang hope on. "The more we know, the better off we are."
And what we know about microbes is the awesome part.
* They are a diverse bunch. Estimates of the number of species range from 150,000 to millions. Only about 1,500 species are human pathogens.
* Plants and animals are "the patina on the microbiological world." Microbial cells probably number 2.5 x 10 to the 30th power, and they contain an estimated half trillion tons of carbon. That's more carbon than all the plants in the world, and possibly more than the total of plants and animals combined.
* Microbes are everywhere. About 66 percent live in the marine floor, 26 percent in the terrestrial subsurface, 4.8 percent in the surface soil, 2.2 percent in the open ocean, and 1 percent in other enviroments, including animals.
* They live where no other life forms could survive: In hot techtonic springs at Yellowstone; in the totally dark, superheated water of hydrothermal vents deep in the ocean; in below-zero, subsurface brine lakes in Antarctica; and in the extreme dry conditions of the Atacama Desert in Chile, where a little rain falls only every few years.
* They do a lot of important things. For example, mammals don't produce all the enzymes they need to digest cellulose. Without microbes to do that for us, we wouldn't even be here.
By John Palen (2012)
Photos: Microbes live in some of the world's most extreme environments, including superheated, deep-sea thermal vents (photo by Olivier Rouxel, Woods Hole Oceanographic Institution) and the Atacama Desert (photo by Henry Bortman, NASA/Astrobiology Program).