Quantitative and scalable measurement of CO₂ production in growing bacterial cultures.

Microbial metabolism sustains the biosphere, driving global biogeochemical cycles such as the carbon cycle. A vital component of the carbon cycle is CO₂, which, in addition to its importance to climate change, is a key physiological property of microbial metabolism. Microbial metabolism is a complex process modulated by genomic structure, environmental variation, and ecology that converts carbon into biomass, metabolic byproducts, and CO₂. Predicting these microbial carbon fluxes from genomic and environmental information is challenging due to (i) the complexity and diversity of microbial physiology and (ii) the lack of quantitative carbon flux measurements. To overcome the challenge of quantification, we focus on CO₂, a single molecule component of microbial carbon flux. Existing methods for quantifying CO₂ are either indirect, error prone, expensive, or not scalable. Here, we report a new measurement of CO₂ production from heterotrophic bacteria utilizing organic carbon aerobically that overcomes the challenges faced by existing methods. Our method is non-destructive, and dynamic, allowing us to track bacterial CO₂ remineralization over time. Our measurement opens the door to rapidly and reliably dissecting how genomic, environmental, and ecological factors impact physiology to drive CO₂ production from bacteria.