Circe (Circe Bioscience) is a Boston-based climate biotech company that engineers microbes to eat carbon dioxide and build valuable molecules - fats, oils, sugars, plastics and fuels - using only CO2, water and electricity. Spun out of Harvard's Wyss Institute in 2021, its gas-fermentation platform consumes roughly 3 kilograms of CO2 for every kilogram of oil it produces, making the process carbon-negative. The company has made the world's first chocolate using fermentation-derived cocoa butter and, in September 2024, raised a $5M seed round to open a pilot plant in Waltham, Massachusetts.
Shannon Nangle is a microbe-wrangling scientist turned CEO who co-founded Circe Bioscience to make fats, oils, and even chocolate out of thin air. Her company feeds carbon dioxide, water, and electricity to engineered microbes that grow like plants and excrete valuable molecules, producing food and industrial ingredients in a carbon-negative way. Spun out of Harvard's Wyss Institute in 2021, Circe made what it calls the world's first gas-fermentation-derived chocolate and has raised over $17 million to scale a manufacturing process Nangle spent six years building.