Fungi: The importance of 98.6 ℉

Fungi: The importance of 98.6 ℉

Candida Auris 

This winter, my family and I drove up to the Adirondacks in upstate New York. Like most of our long car rides, we entertained ourselves by listening to multiple Radiolab podcast episodes. One of these podcasts really caught my attention. This episode, titled Fungus Amungus, focussed on a recently discovered fungus known as Candida Auris. Candida Auris was first discovered in 2009 and has since proven to have a 35% mortality rate in humans. Unlike bacteria, fungus have nuclei and membrane bound organelles. This makes fungal infections immune to antibiotics and thus very difficult to treat. 

Phylogenetic tree

As shown by the photo above, fungi are very similar to animals. This similarity makes finding effective treatments extremely challenging. 

Background Information on Fungi

Fungi are best known for their role as decomposers in plant filled environments where they aid in the recycling of decaying organic material. The most well known types of fungi are mushrooms as well as shelf fungi, a type of fungus that often appears on dead logs. However, unbeknownst to many, there are about 6 million different species of fungi in the world. Most of said fungi inhabit temperate and tropical areas while other fungi, such as lichens, are able to withstand the harsh conditions of Arctic regions. Unlike members of the plant kingdom, fungi are unable to perform photosynthesis in order to create usable chemical energy. Instead, fungi rely on a process known as absorption. As the name suggests, absorption involves a fungus absorbing nutrients from nearby organisms and then digesting said nutrients to create usable chemical energy. These nutrients are absorbed after the fungus releases enzymes which break down the substrate. This reliance on other organisms classifies fungi as heterotrophs like us. A classic example of fungal absorption is when shelf fungus absorbs organic compounds from dead logs in forests.  

Shelf Fungus

The Importance of 98.6 ℉ 

As mentioned previously, fungi are able to inhabit a wide range of ecosystems if a source of nutrients is available. This raises the question, can fungi live in humans? The answer to that question is yes, but only if certain conditions are met. First, the fungus must have a way of entering the body and obtaining nutrients from the human host. Second, the fungus must have sufficient resistance to the human immune system. Third, the fungus must be able to tolerate high temperatures. While many fungi meet requirements 1 and 2, very few species of fungi are able to tolerate the high temperature of the human body. When exposed to high temperatures, the enzymes in most fungi will denature. This stops critical metabolic processes from occurring, thus leading to the death of the fungus. Without a high average temperature of 98.6 ℉, it is likely that humans would be vulnerable to thousands of harmful fungi that are currently unable to inhabit human bodies.

 

Denaturing Enzymes Model

Why 98.6 ℉?

In 1851, Carl Reinhold (a German physician) tested the armpit temperatures of 25,000 people. Reinhold found that the average body temperature of these patients was 98.6 ℉ and his discovery was widely accepted as the normal human body temperature. However, a research study from Stanford University found that the average human body temperature has been decreasing ever since Reinhold's discovery was made. According to data from the study, the normal human body temperature has dropped to 97.5 ℉, 1.1℉ lower than the original average from 1851. While this decrease in temperature may seem negligible, it has the potential to greatly affect the human species. As mentioned previously, high temperatures denature fungal enzymes causing fungi to die. However, because humans are gradually become colder, it is possible that fungi that were previously unable to inhabit humans will now be able to withstand the harsh conditions of the human body. 

Candida Auris is an example of such a fungus. It is suspected that decreases in human body temperature in combination with global warming have led to this fungus being able to live within humans. Unfortunately,  it is likely that there are many more species of fungi just like Candida Auris that are gaining the ability to live within humans everyday. 

I became interested in this topic after listening to a podcast made by RadioLab. You can listen to that here.