A new Arizona State University study shows that two common heterotrophic bacteria can incorporate inorganic carbon, like bicarbonate, into their cells under a range of lab conditions. The process, called heterotrophic inorganic carbon fixation (HICF), challenges the simple view that bacteria only consume organic carbon. The research used isotopic labeling and single-cell imaging to track uptake, revealing that individual cells vary in their carbon use and that environmental factors like temperature and food availability influence the process. These findings have implications for understanding carbon flows in soils, oceans, and deep subsurface environments. While heterotrophs won't replace plants as major carbon fixers, the results suggest a more flexible microbial metabolism that could matter for ecosystem carbon models. The study also has astrobiology angles, potentially expanding where we look for life beyond Earth.
