Scientists gene engineer living mosquito repellent from human skin bacteria

Mosquitoes are notorious for their role in spreading a range of severe diseases, including malaria, dengue fever, and Zika virus.

Traditionally, repellents like diethyltoluamide (DEET) have been used to ward off these pests, but now a breakthrough in microbiology could offer a longer-lasting, non-toxic alternative.

Researchers have engineered common human skin bacteria to repel mosquitoes with promising results that could change the way we approach mosquito control.

A new approach to mosquito repellency

Mosquitoes, particularly the female ones, are attracted to humans and animals through a combination of carbon dioxide , body heat, and odors produced by skin microbes.

Among these, L-(+)-lactic acid—a compound released by certain skin bacteria—is known to attract mosquitoes . Staphylococcus epidermidis and Corynebacterium amycolatum are two such bacteria that contribute to this mosquito attraction.

In a groundbreaking study led by Professor Omar Akbari at the University of California-San Diego, researchers have engineered these bacteria to produce significantly less L-(+)-lactic acid. The idea was to create a version of these bacteria that would reduce mosquito attraction when applied to the skin.

The research team tested the genetically modified S. epidermidis and C. amycolatum on live mice. These mice were painted with either the wild-type (natural) or engineered bacteria and then exposed to mosquitoes.

The results were striking. Compared to the wild-type bacteria, the engineered S. epidermidis attracted approximately 50% fewer Aedes aegypti and Anopheles gambiae mosquitoes and about 22% fewer Culex quinquefasciatus.

The engineered bacteria reduced mosquito attraction by up to 64.4% starting three days after application, with the effect lasting for up to 11 days, as per the press release .

In addition to reducing the number of mosquitoes attracted, the study found that a smaller proportion of mosquitoes that did land on the mice painted with engineered bacteria actually bit them.

This suggests that the engineered bacteria could offer a dual benefit. One deterring mosquitoes from approaching and alsp reducing the likelihood of bites from those that do.

A promising alternative to DEET

The potential benefits of this new mosquito-repellent technology are significant. Current chemical repellents like DEET are effective but have drawbacks, including a shorter duration of effectiveness—typically lasting between four and eight hours.

The engineered bacteria , however, provide a longer-lasting solution with a repellent effect that persists for over a week.

The study, which also involved researchers from Stanford University, was published in the journal PNAS Nexus . The research shows that genetically engineered bacteria could provide a safer and less smelly alternative to regular mosquito repellents.