NOV 11, 2016 5:25 PM PST

Sunscreen, from bacteria?

WRITTEN BY: Kerry Evans
Everyone talks about gut bacteria and how great they are. But what about our skin bacteria? They’re great too!
Researchers from Lund University in Sweden found that Propionibacterium acnes, the most abundant bacterium on our skin, makes an important antioxidant protein.
Don’t let the “acne” part scare you away. It’s not clear that these bacteria cause all cases of acne. According to study author Rolf Lood, “the name originates from the fact that the bacterium was first discovered on a patient with severe acne. But whether it causes acne is uncertain – it may have been present merely because it is so common."
P. acnes lives on your skin!
P. acnes is a Gram-positive rod that hangs out on your skin. Well, not everyone’s skin - people aren’t typically colonized until they reach puberty, then they live with us for the rest of our lives. They also aren’t typically pathogenic, but, as for most bacteria, if they make it into your bloodstream they can make you sick. If you’re really unlucky, P. acnes can cause brain infections and endocarditis, but this is very rare.
On a lighter note, these guys are also used to make cheese. (And who doesn’t love cheese?) Those holes in Swiss cheese? They’re made when the bacteria produce bubbles of carbon dioxide. That Swiss cheese flavor? That comes from propionate made by the bacteria.
So, about that antioxidant protein. Lood and his team found that P. acnes produces a protein called RoxP. What’s interesting about RoxP is that it’s secreted by the bacteria. This suggests that it may modify the environment surrounding the bacteria, making it more hospitable. "This protein is important for the bacterium's very survival on our skin. The bacterium improves its living environment by secreting RoxP, but in doing so it also benefits us,” says Lood.
The researchers tested RoxP’s antioxidant effects by mixing it with free radicals ((2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)-radicals, if you must know). RoxP reduced the free radicals just as well as vitamin E, a well known antioxidant.
Curiously, certain skin diseases like psoriasis and atopic dermatitis are thought to be mediated by oxidative stress, and people with psoriasis have less P. acnes on their skin. So, it’s possible that RoxP not only protects the bacteria from oxidative stress, but it may help us humans as well. Lood’s group is also interested in adding RoxP to sunscreen, counteracting the free radicals generated by UV radiation. According to Lood, “If the study results are positive, they could lead to the inclusion of RoxP in sunscreens and its use in the treatment of psoriasis and atopic dermatitis.”
Sources: Nature Scientific Reports,, MicrobeWiki
About the Author
Bachelor's (BA/BS/Other)
Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
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