Although they’ve developed quite a notorious reputation over the years for the
cause for a variety of deadly diseases, this is only one side of the story.
Although many may not believe it, bacteria are actually more of our friend than
our foe. Very soon you’ll find out how they are fundamental in biotechnology,
many food processes and the protection of human health.
Bacteria’s Role in Food Processing
The human body routinely harbors about 1014 bacteria
– ten times more bacteria than there are cells.
Although they’ve developed quite the reputation for causing diseases, there are
actually many beneficial and essential bacteria that live both on our skin and
inside our bodies. In fact, there are less than 100 species of bacteria that purposely
cause infectious diseases in humans, but more than several thousand species that
exist symbiotically in our digestive systems. These bacteria that live in and on
humans are called microflora. Alot of the time, the relationship between these
microflora and humans are mutualistic (two organisms of different species both
benefit from each other).
Let’s take a closer look at what these beneficial bacteria are, as well as what
they provide us with.
Bacteria on the Skin
bacteria that live on skin are usually either commensal (relationship where
one organism benefits without affecting the other) or mutualistic. As seen
in Image 1, these bacteria can live almost anywhere on the skin: from the surface,
all the way down in the sebaceous glands.
The skin flora’s main role for humans is to act as a line of
defence. They usually prevent pathogenic organisms (those that can cause
disease) from colonizing the skin surface by:
Competing against pathogens for nutrients that are provided by the
Since commensal and mutualistic microflora compete with competing invaders for
the host’s limited resources, it makes it much more difficult for invading
microbes to survive and cause a disease.
Secreting or creating chemicals such as fatty acids, peroxides and
bacteriocins that kill invading microbes.
Stimulating the skin’s immune system so that white blood
cells can destroy any pathogens on the skin.
One example of a beneficial bacteria on our skin is Propionibacterium.
This rod-shaped bacterium uses our
body’s sebum to inhibit the growth of invading pathogens. It does this by converting
the triglycerides found in sebum into free fatty acids; hence lowering the pH
of skin. This contributes to the skin’s acidic pH of approximately 5, which limits
the growth of many common bacteria that can turn pathogenic like Staphylococcus
aureus and Streptococcus pyogenes.
Another similar example of a
mutualistic skin bacterium Pseudomonas
fluorescens. By producing the antimicrobial substance pseudomonic acid, it
not only prevents that bacterial infections such as impetigo, but also inhibits
the growth of fungus species such as Candida albicans – the fungus that can cause thrush. To
give you an idea of how effective this bacterium is at controlling and killing
pathogens that attempt to invade humans, it is actually currently used to
create a commercial antibiotic known as Mupirocin.
although the two mutualistic/commensal microflora mentioned above do not usually
cause disease, in the rare case when there is an imbalance of them, they can
also turn pathogenic.
Bacteria in the Body
the body, the gut contains the largest numbers of bacteria. The gut flora is constructed
during the infancy years of life and play important roles in nutrition,
digestion and immune function. Several examples of such roles include:
Aids in the digestion of food such as fibre.
Enables for the absorption of antioxidants in fruits and
The gut microbiota helps with the production of some vitamins such
as vitamin B12, biotin and vitamin K.
Without the proper balance of gut flora, not only can digestive
issues such as bloating occur, but inflammatory and autoimmune conditions such
as type 1 diabetes may also arise.
One example of a beneficial group of microflora are the
Lactobacillus bacteria. They are a genus of rod-shaped bacteria that have the extraordinary
ability able to produce vitamin K. This is important because vitamin K is essential
to the formation of proteins, blood coagulation, tissue calcification and bone
repair/formation. Vitamin K deficiency can lead to issues such as bone fractures,
bruising and irritable bowel syndrome. Furthermore, Lactobacillus produces an
enzyme that is capable of breaking down lactose (a sugar found in milk) into
lactic acid. This not only enables humans to digest dairy products, but the production
of lactic acid also disrupts the
outer membrane of bacterial cell walls. This assists in inhibiting the growth
of pathogenic microbes such as E. Coli, Salmonella and Candida albicans in the vaginal and urinary tracts; hence
reducing the possibility of infections.
The benefits of bacterial gut flora such as Lactobacillus are so important
to human health that a new commercial industry has been created around them.
The probiotic industry is all about introducing these
….containing microflora that are meant to improve your gut health.
In fact, it is estimated by 2023,
64 billion US dollars.