To Live or Not to Live: The Classification of Nanobacteria

By Hailee Bilimoria

Originally published September 22, 2017

With countless opinions from scientists of all backgrounds, the definition of life has long been disputed. As science has progressed at an exponential rate, the debate has not gotten any easier. Robert Folk, a geologist from Austin, Texas, discovered nanobacteria, or extremely small forms of bacteria, in 1989 and earned the name of “father of nanobacteria” (Buckner 2017). Nanobacteria has added a curious aspect to the discussion, for people are puzzled whether it qualifies as a life form. However, this decision is impossible to make without an agreed upon definition of life. While there are a variety of amazing definitions, a great definition that encompasses a variety of ideas from scientists Gerald Joyce, Franklin M. Harold, and Kenneth Nealson. It states that “life is a self-sustaining chemical system,” (Joyce 1995) is of many shapes and sizes, is capable of self-replication, is able to undergo Darwinian evolution, and is able to “create hallmark molecules and chemical disequilibrium” (Nealson 2002) in the world.  The lack of physical specificity is especially important because it opens up opportunities for unforeseen possibilities of life that could await humankind billions of lightyears away. However, the definition is specific enough to exclude questionable yet definite nonliving things. For example, a puddle follows most of the rules stated but it cannot experience Darwinian evolution or create hallmark molecules, so it is defined as nonliving. However, many scientists who adopt a variety of definitions of life are very puzzled with the classification of small peculiar particles known as nanobacteria. Nanobacterium, also known as nanobes, can be as small as 80 nanometers, earning the title of “the smallest cell-wall organisms on Earth.” They are also “thought to exist everywhere” (Bruckner, 2017), and some scientists suggest that nanobes work together in families of organic material that cause a variety of diseases such as kidney stones or atherosclerosis (Zyga 2008).  Based on the complexity of recently discovered nanobacteria, scientists constantly dispute the classification of it as a living or nonliving organism.

Many scientists believe nanobacteria is living because they can replicate themselves and contain DNA. Finnish scientists Olavi Kajander and Neva Ciftcioglu “claim to have isolated a ‘16S rRNA gene sequence that falls within the α-2 subgroup of Proteobacteria,’ a class of bacterium that includes several human pathogens” (Casem 2003). They were also able to test the reproduction of nanobes by transferring nanobacterium from a biofilm that had been produced in one container to another empty one. Sure enough, another biofilm was created in the new container. They also tested nanobes under gamma radiation, in which no growth occurred. This suggested that the gamma radiation had an effect on the nanobes, proving it was not just some simple chemical reaction (Casem 2003). In addition, John Lieske and his team in Rochester, Minnesota also discovered that nanobes were able to replicate in a culture and were identifiable through a DNA stain, which detects anything containing DNA (Hogan 2004). Although other scientists such as Jack Maniloff of University of Rochester in New York claimed, “I just don’t think this is real,” the American Journal of Physiology accepted Lieske’s findings by conducting their own experiments that further proved their conclusions (Hogan 2004). They isolated the nanobes and added them to samples of calcified aneurysms, which doubled in size within a few weeks when nanobes were added to the surface. They put it under a microscope to reveal the creation of tiny cell-like structures as well. When grown in a flask, the nanobes also absorbed uridine, one of the main building blocks of RNA. With the help of this research, scientists were able to prove that the self-sustainable chemical system of nanobacteria could self-replicate and create hallmark molecules, such as the biofilm, and chemical disequilibrium in the form of calcified aneurysms. 

On the contrary, scientists believe that nanobacterium are nonliving specimen because of their extremely small size and the invalidity of their reproduction. The National Academy of Sciences held a workshop that concluded the most basic life would be between 200 and 300 nanometers, while nanobes can be as small as 80 nm. While they can “reproduce,” they create a calcium phosphate crystal only in certain conditions. Jan Martel of Chang Gung University in Taiwan and John Ding-E Young from The Rockefeller University in New York conducted a study that implied nanobes had a chemical rather than a biological model, for they shared more similarities with sedimentary rocks than they did with living things. Dr. Young stated “Our results clearly disprove that nanobacterium are living organisms… all the previous vast body of literature in nanobacteria can actually be explained by a chemical and abiotic mechanism involving the simple deposition of limestone or calcium carbonate (Ding-E Young 2008).” John Cisar and his colleagues at NIH and FDA labs in Bethesda, Maryland agree, saying the cells of nanobacteria “resemble inanimate structures that form spontaneously in sterile solutions of inorganic calcium and phosphate salts,” meaning nanobes are simply a coalition of nonliving structures that chemically crystallize salts rather than reproduce (NaturalSCIENCE 2000). Although nanobes are self-sustaining chemical systems and can create chemical disequilibrium by means of diseases like kidney stones, according to these scientists, they are nonliving because they are too small to classify as life and their reproduction is invalid. 

Based on the information present, I believe that nanobacterium should be classified as living things because they fully adhere to the combination definition originally stated. Both sides do not disagree that nanobes are self-sustaining chemical systems. Although they differ when it comes to reproduction, I believe the replication of nanobes is valid and not just a chemical reaction due to the fact that they contain DNA and were not able to do so in any environment. If they were able to replicate with gamma radiation, that would mean the replication was chemical, but the radiation seemed to affect their reproduction, just as it may affect the fertility of humans if exposed. One of the largest parts of the nonliving argument is its extremely small size, but my definition of life disregards this and says living organisms can come in all shapes and sizes. Without sufficient information on the evolution of nanobes on both sides of the argument, the lack of proof of Darwinian evolution neither gives nor takes away from the decision. Lastly, the creation of the calcium carbonate that contributed to formation of calcified aneurysms and kidney stones qualify as as the creation of “hallmark molecules and chemical disequilibrium” in the world (Nealson 2002). In summary, the consistency of nanobacteria with the combined definition of life qualifies it as a living organism. 

Both sides to this dispute are valid and contain many scientifically supported arguments, and this will not be solved with my opinion. However, much of the presented evidence points to nanobacterium as living things. If officially classified as living, it would be an important milestone for scientists and potential findings in the future. By expanding the qualifications, it would make the research of extraterrestrial findings much more intensive. For example, an odd-looking rock could be further looked into just for the justification of its living or nonliving classification. Without knowing any other life forms in the universe, it is hard for humans to create a definition that is so specific to our own conditions, and widening the scope also widens the perspective and acceptance of other life forms. For now, as Yossef Av-Gay of the University of British Colombia has said, "’The story [of nanobacteria] seems to be gearing towards the idea that these are not bacteria, but maybe a new living form. It is a very interesting story, but you won't get the answer now’" (Hogan 2004). 

Works Cited

Hogan, J. (2004, May 19). Are nanobacteria alive? Retrieved September 22, 2017, from https://www.eurekalert.org/pub_releases/2004-05/ns-ana051904.php

Bruckner, M. (2017, September 17). Nanobacteria and Nanobes- Are They Alive? Retrieved September 22, 2017, from https://serc.carleton.edu/microbelife/topics/nanobes/index.html

Casem, M. L. (2003). Nanobacteria: Are They or Aren't They Alive? . Retrieved September 22, 2017, from http://sciencecases.lib.buffalo.edu/cs/files/nanobacteria.pdf

NaturalSCIENCE. (2000, November 27). Nanobacteria: not a life-form? Retrieved September 22, 2017, from https://web.archive.org/web/20150905092353/http://naturalscience.com/ns/cover/cover14.html

University of California San Diego. (2002). Classification of Living Things. Retrieved September 22, 2017, from http://earthguide.ucsd.edu/virtualmuseum/litu/01_2.shtml

Zyga, L. (2008, April 23). Nanobacteria - Are They Alive? Retrieved September 22, 2017, from https://phys.org/news/2008-04-nanobacteria-alive.html