BiologyMagazine

Microorganisms as a contributing member of modern-day society

 

Colonies of microorganisms cover a greater proportion of the Earth than we do as humans. Invading and multiplying, passing on their traits to their offspring and by natural selection, they are increasing in their destructive power (Fig.1). Despite their wreaking of havoc on humans on an almost day to day basis without them, we would not be able to function effectively. So, before we all investigate ways in which we can target the 0.01% of bacteria that our cleaning supplies are unable to destroy, we must first understand and appreciate the benefits microorganisms bring to us in order for us to function, whether that is food digestion in our guts or even as cancer treatments.

Figure 1. Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times.

Inside of the human gut – THE MICROBIOME:

There are multitudes of bacteria that live within our guts, particularly in our large intestine, that aid in the digestion of food1. The large intestine is not just an organ made up of cells; it is also an ecosystem, home to multitudes of bacteria known as gut flora or gut microbiota2. Most of us attain gut flora from our mothers, via her faeces and vaginal fluid during childbirth or from her breast milk3. Although our microbiomes mainly consist of bacteria, there are also other microorganisms present such as fungi and viruses. Together, they produce a beautiful biome of microorganisms essential for us to function. In “The Clever Guts Diet”, Dr. Michael Mosley, a former medical doctor with a great interest in nutrition, describes the microbiome as having three vitally important roles, aside from protecting our gut from pathogens and synthesising vitamins. These are:

  1. Regulating our body weight. The microorganisms, bacteria in particular, determine how much energy is extracted from the food that we consume.
  2. Regulating our entire immune system. Affecting the combination of bacteria within your gut can reduce the rate at which infection affects the body, as well as the impact of a range of allergenic and autoimmune diseases.
  3. Converting indigestible food into hormones and other useful chemicals4.

‘Good’ bacteria:

Although there are bacteria in our gut that are essential for effective human functioning, not all bacteria that may be found in someone’s gut is ‘good’ bacteria. It is possible to screen someone to check whether the bacteria found within their gut is beneficial to their body or if it causes adverse effects. Some of the bacteria that should be found in the gut include:

  • Firmicutes: outside of our bodies, this bacterium has many uses, such as the fermentation of alcohol. Within the gut, it is used to aid in the digestion of fats in our diets. This means that the maximum amount of energy can be extracted from the lipids we eat. Especially when food is not as abundant, this is very beneficial.
  • Bacteroidetes: these bacteria are extremely beneficial in order to reduce inflammation in your gut. They hold the very important role of controlling how violent your immune response is, and they break down undigested fibre from vegetables that make their way into the colon, resulting in the production of valuable substances, such as butyrate. Butyrate helps to control the growth of our gut wall cells and maintains our gut lining, which protects us from bowel cancer and ‘leaky gut syndrome’29. Butyrate also provides anti-inflammatory effects.
  • Akkermansia: Found in the mucus that is secreted by our gut in order to protect itself from pathogens, Akkermansia strengthens the gut wall and reduces inflammation. Research done by Belgium scientists also suggests a link between this bacterium and decreasing obesity rates and diabetes5. With global obesity rates having tripled since 1975, research into ways Akkermansia can be used to reduce worldwide obesity is emerging.
  • Lactobacillus: Lining our intestines, Lactobacillus protects our guts from pathogens, and some strains of the bacterium are directly linked to improved mental health. It can be purchased as a probiotic6.

Caesarean Section:

We gain bacteria such as Firmicutes, Bacteroidetes and Lactobacillus during birth. During pregnancy, a mother’s microbiome changes to form an optimum mixture of bacteria for her offspring. The gut flora will then colonise the child’s gut rapidly due to a lack of competition, as the gut, at this moment, is sterile. However, this would be different if a child is born via Caesarean section, as the first bacteria you would come in contact with is from the operating theatre. Research has shown that babies born via Caesarean section have gut bacterial populations that are very different from those born vaginally. Indeed, studies have suggested that these differences could be one of the reasons why babies born via cesarean section have a higher risk of conditions including asthma and type 1 diabetes7. A large study carried out by researchers from Harvard T.H. Chan School of Public Health8 has led to the understanding that babies born via Caesarean section are at a greater risk of developing obesity, both in childhood and as an adult. This emphasises the importance of the proportions of the bacteria living within us and the great health benefits they grant us if they are at right amounts.

An increasing amount of research has been invested in our gut microbiome, as there is the belief that the microorganisms that make up the microbiome impacts how individuals respond to certain drugs and more specifically to how cancer patients respond to chemotherapy9. It has even been suggested that it could be linked to how well we as a society, especially teenagers, sleep10, which has become an interest to many scientists around the globe for many years. Therefore it can be said that our microbiome shapes us and may lead to the curing of many different ailments.

Magic Bullet: Penicillin- The fungus that saved the country

They say not all heroes wear capes, and penicillin is a true testimony to that. Penicillin saved the lives of thousands of soldiers from the terrorising forces of gas gangrene and other bacterial infections. Let us not forget the millions of ordinary civilians who also benefited from this wartime development11. But where was this hero born? Where was it bred? Well, just like some of the many scientific advancements in history, it was by complete chance; an incredible accidental discovery of the bacteria fighting power of Penicillium Notatum12 was made by scientist Alexander Fleming.

Fleming recalls whilst working on various colonies of staphylococcus13, “Further examination of one of the latter showed that a mould colony had developed towards one side of the culture plate…what was astonishing was that in this particular culture plate the staphylococcal colonies for some considerable distance around the mould growth were obviously undergoing lysis.”(Fig. 2)

Figure 2. A photograph of Fleming’s culture dish which lead to the discovery of penicillin.

Fleming goes on to say what emphasises the mighty power of what could be seen as an ordinary fungus, “What had originally been a well-grown staphylococcal colony was now a faint shadow of its former self”.

How penicillin works:

Although Fleming was unable to truly identify how or why this fungus was able to kill the bacteria colonies, in his paper “The Discovery of Penicillin” he does describe it as possibly working in a similar fashion to the enzyme lysozyme. Today we are able to describe the mechanism by which the active ingredient within the fungus, penicillin, acts as an antibiotic.

Penicillin works by inhibiting the enzyme in charge of the final step in the formation of bacterial cell walls14.

This is a huge benefit to humans, as our body cells do not have cell walls; therefore, penicillin can only target susceptible bacteria, leaving our body cells completely unharmed. Furthermore, as penicillin targets the synthesis of cell walls within bacteria, the fungus derived medicine is able to target a broad spectrum of infection. This includes:

  • Pneumonia
  • Scarlet fever
  • Ear, skin, gum, mouth, and throat infections15

This is only a grain of sand compared to the multitude of other infections penicillin can target. Despite this, it is only limited to bacterial infection and so is ineffective against viral and fungal infections16. Nonetheless, the medicinal power of penicillin is so strong it continues to save lives almost one hundred years after its discovery. Perhaps we should not be so quick to throw out our mouldy dishes.

Biological recycling – REDUCING PLASTIC WASTE

Synthetic plastics present in everyday materials account for the main anthropogenic debris present within the Earth’s oceans. Oceans are sources of the necessities of life such as food, energy, and water. They are the main way of international trade, and therefore drive the economy. They are also the main stabiliser of the climate. Hence, changes in the marine ecosystem caused by plastic pollution can have a dramatic global impact on humanity17 (Fig. 3). One of the many ideas considered is the use of microorganisms capable of decomposing plastic.

Figure 3. Potential interactions between marine microorganisms and microplastics in marine environments

In 2016, scientists tested various bacteria against plastic from a bottle recycling plant and found that a strain of bacteria, named Ideonella sakaiensis 201-F6, could digest the plastic used to make single-use drinks bottles, polyethylene terephthalate (PET)18. It works through the secretion of an enzyme, known as PETase. This breaks certain chemical bonds in PET, resulting in smaller molecules that the bacteria can absorb, using the carbon in them as a food source19.

Perhaps isolating this enzyme from the bacterium could be a step in the right direction in regards to reducing plastic waste in our oceans. Some microbiologists already believe that bacteria eating plastic are an important reason for why the plastics numbers do not add up – the amount of plastic we see in the oceans is far less than the total amount of plastic calculated to have been placed there in the first place20.

Although this is a very new discovery and a limited amount of research has yet been published about it, this could pave the way for future research on ways in which plastic can be biologically removed from our world’s oceans. Especially as our carbon dioxide levels in the air are the highest in 650,000 years21, research into ways in which we could reduce the effects of climate change and pollution, I believe, will and should be a dominating aspect of scientific research in the next few decades.

Let us not forget viruses- VIRUSES ARE USEFUL TOO

When we think about viruses, we think of disease spreading pathogens that are hard to destroy as they hijack host cells’ metabolic processes in order to survive and reproduce22. However, they too can benefit us. Examples include the use of natural and laboratory-modified viruses to target and kill cancer cells, treat a variety of diseases through gene and cell therapy and serve as vaccines or vaccine delivery agents23. The ability to treat diseases using viruses, virotherapy, or oncolytic virus therapy has become the subject of intensive research in recent years.

Viruses as an alternative to available treatments

Cancer is the second leading cause of death globally. According to the World Health Organization, cancer is responsible for an estimated 9.6 million deaths in 201824. Conventional treatment of cancer is based primarily on chemotherapy, radiation therapy, and surgery. Although these therapies have increased patient survival rates, their success is often limited depending on the type of cancer being treated. In addition, significant side effects occur because noncancerous cells are also targeted by these treatments. Another grave issue regarding these treatments is the likelihood of recurrence after successful treatment. However, an emerging field in cancer therapy consists of the use of alternative therapies that use viruses to kill cancer cells selectively, similarly to the way magic bullets work, targeting the cancerous cells without harming the result of the body. The idea for this approach came through early observations of cancer regression in patients suffering from unrelated viral infections25. This is a very similar way to which the vaccination for smallpox was discovered26. In the past two decades, viruses from a variety of different families have been studied and have undergone clinical tests in order to understand whether there are potential uses for them as anticancer agents27. It is understood that as a result of protection mechanisms against viral infection being impaired in a large majority of cancer cells, most viruses can replicate to a much greater extent in cancer cells than in normal body cells28. Therefore, cancer cells are more likely to be hijacked and destroyed as the virus undergoes its lytic pathway.

However, as discussed in Oncolytic virus therapy: A new era of cancer treatment at dawn, there still remains the issue of viruses destroying noncancerous cells. Nonetheless, in the near future we should expect to see that the successful completion of several clinical trials and further studies will lead to the approval of additional oncolytic virus therapies.

The potential benefits of microorganisms are far greater than what could be possibly imagined. As we continue to evolve in ideas and develop new forms of technology, the use of microorganisms in a way that benefits humans both inside and outside of the body can only increase. Although microorganisms are the cause of many of the world’s health issues and many people will remain skeptical about their use within our day to day lives, in the words of Albert Szent-Györgyi, who discovered vitamin C, in order for progression to be made “we must see what everyone else has seen, but to think what nobody else has thought”. With more and more scientists are looking to microorganisms as a solution to many of the earth’s problems, in the near future, perhaps microorganisms will be a driving force within our society.

Bibliography:

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  5. Plovier, Hubert, Amandine Everard, Céline Druart, Clara Depommier, Matthias Van Hul, Lucie Geurts, Julien Chilloux, Noora Ottman, Thibaut Duparc, Laeticia Lichtenstein, Antonis Myridakis, Nathalie M. Delzenne, Judith Klievink, Arnab Bhattacharjee, Kees C H Van Der Ark, Steven Aalvink, Laurent O. Martinez, Marc-Emmanuel Dumas, Dominique Maiter, Audrey Loumaye, Michel P. Hermans, Jean-Paul Thissen, Clara Belzer, Willem M De Vos, and Patrice D. Cani. “A Purified Membrane Protein from Akkermansia Muciniphila or the Pasteurized Bacterium Improves Metabolism in Obese and Diabetic Mice.” Nature Medicine 23, no. 1 (2016): 107-13. doi:10.1038/nm.4236
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Images:

[Figure 1] Eric Erbe, digital colorization by Christopher Pooley, [online] Available at: http://commons.wikimedia.org/wiki/File:E_coli_at_10000x,_original.jpg [Accessed 28th April 2019]

[Figure 2] Fleming, Alexander. “The Discovery Of Penicillin.” British Medical Bulletin 2, no. 1 (1944): 4-5. doi:10.1093/oxfordjournals.bmb.a071032

[Figure 3] Urbanek, Aneta K., Waldemar Rymowicz, and Aleksandra M. Mirończuk. 2018. “Degradation Of Plastics And Plastic-Degrading Bacteria In Cold Marine Habitats”. Applied Microbiology And Biotechnology 102 (18): 7669-7678. doi:10.1007/s00253-018-9195-y

Elizabeth Neri

Elizabeth is an A level student who hopes to pursue a career in medicine and medical research, as a result of her deep interest in immunology and how the body responds to microorganisms. She studies Maths, Biology, Chemistry and English Literature and hopes that her love for science never dies.

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