Looking for life in all the wrong places.

Being boiled alive has never seemed like an exciting activity to me.  It’s not that I don’t enjoy a good cup of boiled water (tea leaves preferably included) I would just rather not be immersed in it.  It has a remarkably negative impact on human life expectancy, because we just aren’t built to withstand temperatures of 212ºF (100ºC).  I’ve also got to believe, that awareness of the safety hazard of very hot substances, is far from a recent development.  One has to imagine that shortly after fire was discovered, some one to two million years ago, that it was followed by the discovery of stop, drop, and roll.

Boiling bacteria on the other hand, was a largely unconsidered endeavour until much later.  Antonie von Leeuwenhoek learned that such things existed back in the late 1600’s when he was busy looking into drops of water and scraping the plaque off of his teeth.  Leeuwenhook was probably more interested in trying to find more “animalcula” than in boiling them alive so the 1600’s came and went without this being a real passion project of any one individual (though Leeuwenhook did seem to find time to douse them with wine vinegar).  It wasn’t until 1799 when an Italian priest, Lazaro Spallanzani, decided to spend his days boiling seeds.  From his seed boiling experiments, or more specifically the boiling of organisms on those seeds, it was realized that not all animalcula are created equal as he notes in Observations and experiments upon the animalcula of infusions.  Some of what, he termed, “higher class” animalcula (presumably because of their top notch performance at italian dinner parties), were readily killed by boiling for short periods, while other “lower class” animalcula were characterized by greater heat resistance (and presumably a love of Olive Garden).  The truth of the matter is that once this small organisms died they didn’t come back and this was the beginning of the end of the idea that these organisms arose spontaneously out of the ether.

By the 1860’s Louis Pasteur had shown that if you boiled nutrient broth it would remain sterile unless it was exposed to particulates in the air. That said there were still hold outs.  Proponents of spontaneous generation, such as Félix Archimède Pouchet and Henry Charlton Bastian, continued to point to materials that were not so easily sterilized.  For example hay soaked in water continued to show signs of life even after it was boiled, which they interpreted as evidence that these small organisms were a simple spontaneous product of dead hay.  A German botanist by the name of Ferdinand Cohen, looked at this situation more carefully in the 1870s.  Cohen realized that this growth was a product of a small rod shaped bacterium.  After boiling, the rods disappeared but small spheres, that readily caught the light, remained.  If these spheres were given nutrients they started to turn back into the rods and began to grow and divide.

bacillus-subtilis

The rod shaped cells and bright spherical spores of Bacillus subtilis.  I can only assume that it also loves Olive Garden and unlimited bread sticks.

It was at this point Cohen realized what he was working with; this was no magic hay, but instead a group of heat resistant spores!  He named the organism Bacillus subtilis and thus discovered one of the first examples of bacterial sporulation and crushed some of the last remaining arguments for spontaneous generation.

The funny thing is that bacterial spores are hardly the only exception to the general rule of boiling = death.  For example, hydrothermal vents for a long time were thought to be sterile wastelands, but in 1977 all of that changed when submersibles captured a spot teaming with life.  Before that in 1966 Thomas Brock managed to find bacteria in hot springs at temperatures again where bacteria weren’t thought to exist.  Brock discovered an organism that could readily grow upwards of 158ºF (70ºC) and didn’t form spores.  This bacterium, known as Thermus aquaticus, is responsible for pretty much all modern DNA technology thanks to the incredibly heat resistant DNA polymerase it produces.

So I guess it pays to look for life where we don’t expect to find it.  The exceptions to the rules are sometimes just more interesting than the general use case.  That said I still won’t be jumping in boiling water.  Not even for unlimited bread sticks.

2 thoughts on “Looking for life in all the wrong places.

  1. Very cool overview of the scientific history that led to the discovery of Bacillus subtilis and other extreme organisms. Led me down a very interesting Wikipedia adventure : )

    Liked by 1 person

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