Research Article: Life in a World without Microbes

Date Published: December 16, 2014

Publisher: Public Library of Science

Author(s): Jack A. Gilbert, Josh D. Neufeld

Abstract: Life in a world without microbes Can a macrorganism survive without commensal microbes in a world of microbes? What would happen if all microbes on earth suddenly disappeared?

Partial Text: Or would it?

The concept of animals existing in complete isolation from microorganisms originated with Louis Pasteur [1], who also predicted that an animal’s existence would be impossible without microbial life. Ten years later, George Nuttal and Hans Thuerfelder disproved Pasteur’s prediction by removing microorganisms from a guinea pig [2]. Much later, James Reyniers and colleagues reared rats and chickens in gnotobiotic conditions (gnos, known; bios, life; i.e., “germfree”), enabling the development of germfree animal populations for research [3],[4]. Reynier’s bioengineering-driven efforts to generate “pure units” of biology for experimental study resulted in technology that enabled gnotobiotic life. Thus began not only a field of scientific endeavor that would alter the face of medical and biological study but also a cultural phenomenon centered on an obsession with eliminating microorganisms from the human experience, with extremes leading to “germophobia.”

What if we could live a germfree life outside the bubble? What if all prokaryotic microorganisms on Earth disappeared suddenly? If someone were to wave an antimicrobial wand and eliminate all bacterial and archaeal life on the planet, what would happen? The usual rhetoric is that life as we know it would end, human societies would collapse, and eukaryotic life would cease to exist. Is all of this true?

If the antimicrobial wand were waved, this time removing all microbes (i.e., viruses, Bacteria, Archaea, fungi, and protists—algae and others) from the planet, what would happen next?

Microbes sustain life on this planet because of their myriad associations and biogeochemical processes. Nonetheless, their roles are not necessarily irreproducible. When you next hear someone claim that we cannot live without microorganisms, it would be appropriate to ask them to qualify the statement. Would we still be able to eat and digest food? Yes. Would life be extinguished in the absence of Bacteria and Archaea or in a world without any microbes? Not immediately, not all life, and potentially not for a long time.



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