It’s been over 25 years since the FDA approved a new ingredient for sunscreen in the United States. But a molecule called gadusol found in fish and coral reefs is a promising candidate. It absorbs U.V. rays — acting like a built-in sunscreen for fish. But there’s a big hurdle if scientists want to turn gadusol into human sunscreen: They’d need to make a lot of it. A new study out this week in the journal Trends in Biotechnology takes us a big step closer. Their solution? Using the bacteria best known for making your stomach hurt: e. Coli. Interested in more science? Email us your question at shortwave@npr.org.Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.