A probiotic cream that increases heat production could prevent frostbite

Polar explorers and deep-sea divers could one day apply probiotic cream to their skin to prevent frostbite or hypothermia. The optimism comes after scientists for the first time genetically engineered bacteria that naturally live on our skin to detect temperature and produce more heat when needed.

“It’s very creative work. You can imagine that this cream is the difference between you getting frostbite or not,” he says Harris Wang at Columbia University in New York, who was not involved in the research. “I can think of many applications – from keeping warm in the winter, preventing frostbite during expeditions, to deep diving – where heat generation is important.”

Guillermo Nevot Sanchez at Pompeu Fabra University in Barcelona and his colleagues genetically modified a strain of this bacterium Cutibacterium acnesone of the most abundant microbes on healthy skin, producing twice as much heat as normal. They did this by using CRISPR, a genetic tool, to change the levels of a protein called arcC, which is involved in generating energy.

The team also used CRISPR to alter the expression of heat-sensitive genes in a separate dose C. acnes. This meant that the microbes could detect temperatures above 32 °C (90 °F), signaling with a fluorescent signal.

Together, these findings provide the first proof of concept that skin bacteria could be engineered to produce more heat in response to a change in temperature, says Nevot Sánchez. The team now needs to combine these two abilities in the same bacterium and demonstrate that it can detect a dangerous drop in temperature, not just when it is high.

Nevot Sánchez says the team has performed experiments that have not yet been published that show C. acnes strains can survive when mixed into a cream.

“We could develop a probiotic cream that you apply to most of your body – for example before going out in cold places – to prevent hypothermia,” says Nevot Sánchez, who presented the research at the Synthetic Biology for Health and Sustainability conference in Hinxton, UK on the 12th. It could even help people who live in harsh climates and don’t have heating, he says.

But more research is needed to test how well such a cream actually heats human skin samples in the lab and on mice before testing it on humans, Wang says. Engineering ways to kill the bacteria when necessary – for example by applying a second cream – will also be essential to limit potential side effects such as overheating, says Nevot Sánchez.

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