Circe

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.