The Curious J: A science blog

Exploring life, one atom at a time.

The Invisible World of Microorganisms

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As humans, it’s difficult to imagine the world in a scale that is different than our own, especially when that difference is significant, such as the expanse of the universe or the workings of a cell. That’s what makes microorganisms so interesting. There is an entire world among us and in us that is invisible to the naked eye. Now, not only are we aware of these hidden communities, but we use microorganisms in a wide range of industries, and we also know that the bacterial communities living inside and on us help keep us healthy. With all of this unseen activity among us, learning about microorganisms opens up our eyes and minds to an once-invisible world.

What is a microorganism anyway? 

The simplest definition of a microorganism, or microbe, is an organism that is too small to be seen by human vision, i.e. can only be seen with a microscope. Of course, microbes are much more complex and diverse than this definition implies. First off, microbes can be single-celled organisms or multicellular, and there are several categories of microbes: bacteria, archaea, fungi (includes yeasts, molds, and mushrooms), protista (algae and protozoa), and viruses.

Bacteria:
E. coli

Escherichia coli 
Archaea:
archaea
Pyrococcus furiosus
Fungi:
Fungi
Zygomycota rhizopus
Protista:
protista

Noctiluca scintillans
(Sea Sparkle; protozoa)
Viruses: 
Virus
Orthomyxovirus (Influenza)

Viruses are especially interesting in that it has long been debated whether viruses are “living” organisms are not, since they lack one of the seven characteristics of life: the ability to reproduce on their own [1]. Viruses need cells from other organisms in order to replicate, or reproduce. That is also why they are considered such a threat to our health—they can move from cell to cell, replicating and usually killing the cells they inhabited along the way. As I’ll soon discuss though, viruses can also be used for good.

Microbes are actually everywhere

Microbes can be found in any type of environment, including the human body. Since they can be found virtually everywhere, I’m only going to describe the more extreme habitats. Microbes living in these conditions are known as extremophilesTo start with, microbes can be found in the deepest parts of the ocean. When divers first discovered hydrothermal vents at the bottom of the ocean, they were surprised to find thriving communities of life there [2]. It turns out that microbes, especially archaea, are adept at surviving in extreme conditions; in this case those conditions are extreme pressure, and temperatures up to 350°C (662°F)! Microbes can also be found in the freezing temperatures of the arctic. On February 6, 2013 scientists first reported bacteria found a half-mile deep under the ice of Antarctica. In fact, since the arctic isn’t hospitable to other forms of life, bacterial communities dominate the biodiversity [3].

Radiation is scary for humans even at very low doses, but there are microorganisms that can withstand extremely high levels. These microbes exhibit “radio-resistance”: resistant to ionizing radiation [4]. A lethal dose of radiation for humans is approximately 4-10 gray (Gy), while these organisms can survive radiation of at least 1000 (Gy) (100x more than humans!) The most extreme example is Thermococcus gammatolerans, rightly named after its ability to survive 30,000 (Gy)! [5]

And last, but certainly not least, there are astronaut microbes! When the unmanned lunar lander Surveyor 3 returned to earth, NASA scientists were surprised to find living Streptococcus mitis from Earth that had survived on the lander for 31 months in the vacuum of space [6].  Since then several microorganisms have been identified as having the ability to survive in space, and these include one of my favorite organisms (micro or macro): Tardigrades! Also known as “water bears”, because they literally look like little bears, these little guys are the ultimate extremophiles. Not only can they survive in space, they are also radio-resistant and can survive radiation levels up to 5,700 (Gy), as well as in temperatures below freezing and above boiling. To top it off, they can survive more than 10 years without food or water [7]. Basically, Tardigrades will outlive us all.

Some other not-so-common places that microbes are commonly found: bubbling tar, steam vents, boiling water, in soil and ice miles underground, and most likely in areas that humans have been unable to discover thus far [8].

Water Bear
 Tardigrade (Water Bear)

 

Humans and Microbes: A love-hate relationship

The term “human microbiota” is becoming increasingly well-known as we learn more about our close interactions with microorganisms, but as a short description: the human microbiota, or microflora, is the collective of microbes that live on the surface and in layers of the skin, the saliva and oral mucosa, in the conjunctiva (lines the inside of the eyelids), in the gastrointestinal tract, in the respiratory system, and in the vagina [9]. The interactions between the human body, the microbiota, and the environment are so complex that I’m not even going to go there in this post. What I do want to discuss though, is how microbes are actually helping us!

Bacteria in our body play vital roles in keeping us healthy – they interact with and boost our immune systems and even combat pathogenic microbes (ones that cause disease). The bacteria on our skin act as an extra layer of protection against any bad guys getting in or on us. In a nut-shell, having these communities of good bacteria in and on our bodies helps prevent bad communities from moving in [10]. In fact, bacteria play such an important role in our health that there are more bacterial cells in our bodies than our own actual cells [11].

Microbes are also used to improve our health and combat diseases in more targeted ways. An example of this is the use of microbes as vehicles, or carriers, for medicine. Some bacterial strains are commonly used as “delivery capsules” for drugs that are normally toxic when taken alone. E. coli has been engineered to transport an enzyme specifically to cancer cells, without targeting and harming other cells [12].

Viruses are also being used to treat cancer, as a team from Massachusetts General Hospital and Harvard Medical School used engineered Herpes Simplex Virus Type 1 (HSV-1) as vectors for targeting cancer cells [13]. Using viruses or other microbes as vehicles could eliminate more dangerous types of treatment such as chemotherapy. Microorganisms can also be genetically engineered to target tumors and specific areas of the body that are under attack from disease.

Other ways that microbes are helping us range from food production to toxic cleanup. Yeasts are commonly used for bread and beer production and various bacteria are used for cheese production. Microbes are also exploited for the compounds they make: including enzymes, vitamins, and antibiotics. For example, penicillin was originally isolated from the fungi Penicillium, and lactic acid is used as a food preservative. Microbes are also essential to agriculture and nutrient recycling. Microbes living in the soil break down nutrients that are found in their environment, and provide things like nitrogen to plants in a process called mineralization [14] (side note: bacteria also break down nutrients in the GI tract to help humans digest them better). As mentioned, microbes are also used for cleaning up environmental toxins, including oil spills. Some microorganisms actually use oil as fuel, so that they can be released into a contaminated area and, given enough time, the oil will be removed [15]. This is a promising approach to cleaning up other toxins found in soil and water in a relatively safe and hands-off way.

 

I could honestly go on and on about the wonders and curiosities of microorganisms, but for the sake of keeping at least some readers I’m going to stop here. I hope you enjoyed reading about these amazing organisms, and have a new-found or refreshed appreciation for the invisible world of microbes. Now I dare you to look at anything around you, even in the mirror, and not think about how many microorganisms are there…good luck, and welcome to my world.

 

Work Cited:

  1. http://infohost.nmt.edu/~klathrop/7characterisitcs_of_life.htm
  2. http://www.ucmp.berkeley.edu/fungi/fungi.html
  3. https://en.wikipedia.org/wiki/Archaea#Morphology
  4. http://www.microbeworld.org/types-of-microbes/bacteria/42-what-is-a-microbe-sp-828/types-of-microbes/138-bacteria
  5. https://microbewiki.kenyon.edu/index.php/Deep_sea_vent
  6. https://en.wikipedia.org/wiki/Antarctic_microorganism#Climate_and_habitat
  7.  http://morgana249.blogspot.com/2014/08/6-organisms-that-can-survive-fallout.html
  8. https://microbewiki.kenyon.edu/index.php/Thermococcus_gammatolerans
  9. http://www.panspermia.org/bacteria.htm
  10. https://en.wikipedia.org/wiki/Tardigrade
  11. http://www.livescience.com/29865-strangest-places-life-found.html
  12. https://en.wikipedia.org/wiki/Human_microbiota#Anatomical_areas
  13. http://www.scientificamerican.com/article/ultimate-social-network-bacteria-protects-health/
  14. http://schaechter.asmblog.org/schaechter/2014/07/microbial-to-human-cell-ratio-just-bragging-rights.html
  15. http://www.wpi.edu/Pubs/E-project/Available/E-project-040912-094932/unrestricted/Jared_Guttmann_Investigations_into_the_Current_Usage_of_Microbes_in_Medicine.pdf
  16. http://www.nature.com/cgt/journal/v9/n12/full/7700537a.html
  17. http://www.ext.colostate.edu/mg/gardennotes/212.html
  18. http://www.scientificamerican.com/article/how-microbes-helped-clean-bp-s-oil-spill/

Further Links: 

Wikipedia: Microorganisms  https://en.wikipedia.org/wiki/Microorganism
Fungi Information  http://www.ucmp.berkeley.edu/fungi/fungi.html
Archaea Information  https://en.wikipedia.org/wiki/Archaea#Morphology
Protista Information  http://www.microbeworld.org/types-of-microbes/protista
Virus Information  http://www.ucmp.berkeley.edu/alllife/virus.html 
Tardigrade Information  http://tardigrades.bio.unc.edu/ 

Author: The Curious J

Molecular biologist by trade, environmentalist in spirit, and human being by nature - exploring this amazing world through the lens of science (or at least my take on it). This blog is a passion project that allows me to combine writing, research, average wit, and sometimes significant controversies. Welcome and thank you for reading!

3 thoughts on “The Invisible World of Microorganisms

  1. Concise, yet thorough. Well written and easy to read. Great job and keep it up!

    PS send me an email, got a a question for you. 🙂

    joe@sanelijo.org

    Like

  2. Hey, I realize I should have told you why I asked for you to contact me. I run a habitat restoration program at San Elijo Lagoon in San Diego County, and I send an ‘eblast’ every week to about 200+ volunteers about various things regarding the lagoon and the restoration program. In addition, I always include a link to an interesting scientific article just to get people learning and inspired. I wanted to see if you wouldn’t mind me using one of your posts in my email. You’re a great writer, and I feel that even those who aren’t as well versed in science can easily follow along. I wouldn’t ever post your blog without your permission, so let me know if it’s okay with you! It could be good exposure if that’s something you’re striving for with this blog. joe@sanelijo.org

    On a side note, you mentioned in one of the posts that you have a background in English. I feel like those who come to science from other disciplines make great scientists. I took a different path to science as well, and I feel like it serves me well. Or at least that’s my ‘theory,’ hehe 🙂 .

    Cheers,

    Joe

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  3. Pingback: Genetic Engineering: The Good, The Bad, and The Ugly | The Curious J: A science blog

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