A probiotic cream can make visits to extremely cold environments a little safer
Aurora images, USA
Polar explorers and deep-sea divers may one day apply a probiotic cream to their skin to stave off frostbite or hypothermia. This optimism comes after scientists genetically engineered bacteria that naturally live on our skin to sense temperature and produce more heat when needed, for the first time.
“It’s very creative work. You can imagine that this cream is the difference between getting frostbite or not,” says Harris Wang of Columbia University in New York, who was not involved in the research. “I can think of many applications – from keeping warm in winter, preventing frostbite during expeditions, to deep-water diving – where generating heat is important.”
Guillermo Nevot Sánchez at the Pompeu Fabra University in Barcelona and his colleagues genetically engineered a strain of the bacterium Cutibacterium acnesone of the most abundant microbes on healthy skin, to produce twice as much heat as normal. They did this by using CRISPR, a genetic tool, to change the levels of a protein called arcC that is involved in generating energy.
The team also used CRISPR to alter the expression of heat-sensitive genes in a separate batch of C. acnes. This meant that the microbes could detect temperatures above 32 °C (90 °F), which they flagged via a fluorescent signal.
Together, the findings provide the first evidence that skin bacteria can be engineered to produce more heat in response to a change in temperature, says Nevot Sánchez. The team must now combine these two abilities in the same bacterium, and demonstrate that they can detect a dangerous drop in temperature, not just when it is high.
Nevot Sánchez says the team has carried out experiments, which have not yet been published, which show C. acnes strains can survive when mixed into a cream.
“We can develop a probiotic cream that you put over most of the body – before going to cold places, for example – to prevent hypothermia,” says Nevot Sánchez, who presented the research at the Synthetic Biology for Health and Sustainability conference in Hinxton, UK, on March 12. It can even help people who live in harsh climates and don’t have heating, he says.
But further research is needed to test the extent to which such a cream actually warms human skin samples in the lab and on mice before testing it on humans, Wang says. Technical ways to kill the bacteria when desired – for example by using a new cream – will also be essential to limit potential side effects, such as overheating, says Nevot Sánchez.
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