The microscopic world is full of wonders and mystery; it is a vibrant and active universe of organisms, collectively called microbes, too small to see with the naked eye. Some of its inhabitants live in small communities, while others form colonies so large that you can actually see them. They may be small, but their role in nature is definitely far from insignificant.
One can say that our existence alongside theirs is highly intertwined and in many ways symbiotic; from food fermentation, sewage treatment and fuel production to medicine, bioengineering and farming, the effect of microbes in human culture and health is profound in many ways.
In the human body, we benefit from them too, like the essential gut flora. However, like the great majority of movies and drama, where you have heroes you will have villains too.
The Human Body And The Invisible Microbes
Besides bacteria, the microbes present in and around us include also archaea, fungi, protists and viruses. Some of these co-exist with us without harm, others share with us a mutually-beneficial relationship and can cause harm.
To illustrate how intertwined this relationship is, some have referred to the human skin as a virtual bacteria zoo while the human gut is like a rainforest. The scale is so massive that scientists have yet to completely identify all of them, only a measly 1% have been identified and characterized.
On The Skin
As the human skin functions as a shield against disease-causing microbes, it also serves as incubating environment for a great number of microorganisms (skin flora) that reside on the skin's surface. A study of twenty skin areas on healthy people found that a sophisticated make-up of bacteria types (Actinobacteria (51.8%), Firmicutes (24.4%), Proteobacteria (16.5%), and Bacteroidetes (6.3%)) and a large number of fungal types live on healthy human skin where oil and sweat secretions provide the nutrients.
Pros And Cons
Skin flora is usually harmless, either providing no significant benefits nor harm, or mutualistic where both you and the bacteria mutually benefit. The benefits that they provide include preventing otherwise harmful microorganisms from proliferating and colonizing that can lead to inflammation of the skin; they do so by competing for nutrients, secretions that act against them, or by stimulating your skin's natural immunity. However, some of these mutualistic microbes can also cause diseases; one example is the bacteria Pseudomonas aeruginosa that can cause infections in bone, joint, gastrointestinal, and respiratory systems if it enters the blood system and your immunity is unable to neutralise it. On the other hand, it produces antimicrobial substances that help defend you from staphylococcal and streptococcal infections and inhibit the growth of some fungus species.
In The Gut
Gut flora is the complex mix of microorganisms that call the digestive tracts animals, including humans, their home and eatery.
Gut microbiota in humans possesses the greatest number of bacteria and species as compared to other areas of the human body. One to two years after birth, the human gut flora establishes itself in the inner lining of the intestinal tract where intestinal secretions help the organ become tolerant to and even supportive of the presence of gut flora. The secretions themselves also function as a deterrent to harmful microbes and compounds.
The relationship we share with the microbes in our gut is more mutualistic in nature.
Pros And Cons
Gut microbiota in humans possesses the greatest number of bacteria and species as compared to other areas of the human body. Some of these microorganisms help you by fermenting dietary fibre into nutrients that are then absorbed. Studies have also shown evidence of gut flora contributing to your body's anti-inflammatory and immune responses.
In The Vagina
It may sound a little uncomfortable, but as it turns out, the vagina benefits from microorganisms too! These microbes play a crucial role in protecting your intimate areas from infections and significantly implicate a woman’s overall health.
Pros And Cons
Bacteria from the Lactobacillus genus secrete compounds like lactic acid, hydrogen peroxide and antimicrobial compounds that suppress harmful microbes by producing hydrogen peroxide and lactic acid. However, some bacteria like Candida albicans and Gardnerella vaginalis can cause infections or encourage harmful bacteria to thrive.
In The Mouth
Unsurprisingly, the mouth is a hotbed for a host of microorganisms, providing ample water, nutrients and temperature that make for a conducive environment to thrive in. Microbes can adhere themselves to teeth and gum to prevent being flushed down to the stomach where acids can destroy them.
Pros And Cons
We all agree that acid in the mouth causes tooth decay and the erosion of enamel, but there is some slight encouragement for those suffering from it. The Veillonella bacteria thrive in acidic environments and is thought to slow down the development of cavities by converting acidic products of other species into less acidic ones. With good oral hygiene and your natural immune response, the growth of bacteria in the mouth can be kept in check and not cause problems.
Now we know that not all microbes are deserving of that invisible evil characterisation. We have been living in, around, alongside and with microbes and will continue to do so. With the right mindset, hygiene and dietary practices, we can benefit from the good that some microbes give to us while keeping the bad ones in check and incapable of doing harm.