Our microbiota: A tenant in the skin's defense.

By Sarah-Eve Papineau, Chemist at Corpa Flora specialized in cosmeceuticals

It's sometimes hard to believe that we have billions of bacteria on our skin and even harder to know that they are continually protecting us. This happy mix of bacteria, yeast and molds, commonly known as the microbiota, has been studied extensively in the gut, but the skin also hides some secrets.

Who are these occupants, what do they eat and why are they safe?

First of all, although there are about four hundred different families of bacteria, we can recognize the good bacteria from the bad:

Good :

Staphylococcus epidermidis

Bifidobacterium (group)

Bad :

Propionibacterium acnes

Streptococcus pyogenes

Staphylococcus Aureus

Malassezia furfur

Distinguishing between "good" and "bad" bacteria is important to understand how our skin works so we can tailor our skincare routine to benefit the right group.

[Image Malassezia furfur SEM lores] ID#: 213 Description: Scanning Electron Micrograph of Malassezia furfur. Content Providers(s): Robert Simmons/Janice Carr Photo Credit: CDC/Janice Carr

Some of our habits are harmful to the health of our microbiota. For example, when we use a foaming cleanser that contains abrasive emulsifiers, it removes all the oil from the skin and damages the hydrolipidic film. Since the hydrolipidic film is the home of beneficial bacteria, they are left without shelter and food.

Sometimes the pH of the cleanser affects the pH of the skin, making the environment uncomfortable for the good bacteria. They leave the skin, leaving an unoccupied space. Bad bacteria quickly colonize this space. This is when the problems start: inflammation, acne, dehydrated skin and so on.