Bacteria Viruses Human Survival

extremophile

MSN Now reports that researchers from several Scottish universities predict that in a billion years the sun will become so luminous that it will evaporate the oceans.  Since water vapor is a kind of greenhouse gas, a greenhouse effect will heat up the Earth by 220 degrees or more. But there are certain forms of microbial life that could nevertheless survive.  Perhaps humans could also survive as organisms like bacteria and viruses.

 The process of global heating is already being experienced.  The burning of fossil fuels release greenhouse gases, mainly carbon dioxide (CO2) and nitrous oxide (NO), which trap heat close to the Earth’s surface, thereby causing surface temperature to increase.  The U.S. Environmental Protection Agency estimates that the temperature has already increased by 1.2 to 1.4° degrees in the last 100 years.  The temperature will continue to rise, melting ice caps, raising oceanic water levels, and triggering extreme weather events.

As the earth heats up, oxygen levels will fall, killing off plants and larger animals, leaving only the extremophiles, possibly persisting deep underground. An extremophile is an organism that can thrive in physical or geochemical conditions that are detrimental to most other life on Earth. Organisms that live in more moderate environments are called mesophiles or neutrophiles.

Extremophiles can endure intense pressure and heat.  We know that some organisms like extremophiles can flourish in environments with no oxygen at all.

Extremophiles exist under the ocean, at high altitudes, inside rock and in the pores between mineral grains. (Microbial Life Educational Resources.) They are also found in hydrothermal vents (fissures in the planet’s surface from which geothermally heated water emerge).

Interestingly, “extremophile” is derived from the Latin extremus, “extreme” and the Greek philiā, “love.” Extremophiles may be evidence that love never dies.

Viruses live in extremophiles, as they do in all other organisms. They can survive in extreme heat and cold as well.  They are even being considered one of the means of the transmission of information into space. They are much smaller than bacteria.  While the smallest bacteria are about 0.3 micrometers, the largest viruses are 400 nanometers in size. One micrometer is 1000th the size of a millimeter, or one-millionth of a meter.  By comparison, human hair has a thickness of approximately 80 micrometers.  A nanometer is one-billionth the size of a meter.

Fine, you say.  But what do microorganism like bacteria and viruses have to do with human survival?

A human being is a nest of microorganisms.  In an article in the May 2013 issue of the Smithsonian, writer Richard Coniff reports that scientists describe the community of bacteria, fungi and viruses in and around the human body as a “biodome.”  While the human body consists of more than ten trillion cells, microbes account for 100 trillion cells.  By cell count, then, human beings are only ten percent human. While a human body is made up of 21,000 genes, the microbes within us add another eight million genes.  So human genes account for two-tenths of a percent of the total.  Fortunately, microbes weigh about three pounds, about as much as the human brain.

Humans harbor more than 10,000 microbial species, 1,000 of them in their mouths alone.

In the January 2013 issue of National Geographic, scientist Nathan Wolfe observes that when we inhale, our nostrils take in millions of particles—including dust, pollen, volcanic ash and plant spores—that are abounding with bacteria and viruses.  These organisms inhabit the air we breathe and the upper atmosphere, 220 miles above the Earth’s surface. Most are beneficial, helping us to digest our food, absorb nutrients, and train our immune systems to fight infections.  They secrete a substance on our skin that prevents cracks through which pathogens could pass.  They also manufacture vitamins and anti-inflammatory proteins that cannot be produced by our own genes.

Bacteria are responsible for as much as half the oxygen made on Earth each year.

Bacteria are even indirectly responsible for the creation of oxygen, because in the early stages of the Earth’s development, cyanobacteria became embedded in cells that evolved into plants.  Meanwhile, the bacteria evolved into chloroplasts, the engines of plant cells for photosynthesis.  Photosynthesis is the method by which plants convert the energy of the sun into sugars. In the process, they free oxygen from water.  Thus the byproduct of photosynthesis is the air we breathe.  Distant cousins of those early cyanobacteria in plant cells continue to do most of the work of photosynthesis.

If man is composed mostly of microorganisms, and extremophiles are microorganisms, it is possible (if unlikely) that extremophiles would find their way into the human body. Thus bacteria and viruses could be a conceivable way for humans to survive the incredibly harsh conditions of a future Earth.

By:  Tom Ukinski

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