Circe, a startup founded by Dr. Shannon Nangle in Cambridge, Massachusetts, is at the forefront of a new wave of companies utilizing gas fermentation to create sustainable, functional fats. While most startups in this field rely on sugars to feed their microbes, Circe stands out by feeding its microbes carbon dioxide, hydrogen, and oxygen, offering a more efficient and environmentally friendly alternative. Dr. Nangle envisions a future where their technology can produce fats that are cost-competitive with traditional dairy fats, cocoa butter, and palm kernel oil. The gas fermentation process not only reduces costs by using cheaper feedstocks but also allows for continuous operation, leading to decreased unit costs. Circe's approach involves precision fermentation, genetically engineering microbes to produce mimetics of dairy fats or palm oil fractions. The company's microbes require carbon dioxide, oxygen, and hydrogen, sourced ideally from the atmosphere and electrolysis powered by renewable energy. The pilot-scale gas fermentation facility built by Circe is a significant step forward in their journey. It can operate in various modes like loop, air lift, and bubble column, showcasing the versatility of their technology. With a focus on sustainability, resource efficiency, and innovative biotechnology, Circe is poised to revolutionize the fats production industry.