To better leverage microbiology in addressing climate change and other sustainability challenges, the International Union of Microbiological Societies and the American Society for Microbiology brought us (the authors) together in December 2023 — as a group of microbiologists, public-health scientists and economists with expertise in health, energy, greenhouse gases, agriculture, soil and water. In a series of meetings, we have assessed whether certain microbe-based technologies that are already on the market could contribute to sustainable solutions that are scalable, ethical and economically viable. We have identified cases in which the technical feasibility of an approach has already been demonstrated and in which solutions could become competitive with today’s fossil-based approaches in 5–15 years.