Inferring Microbial Biomass Yield and Cell Weight using Probabilistic Macrochemical Modeling

Growth rates and biomass yields are key descriptors used in microbiology studies to understand how microbial species respond to changes in the environment. Of these, biomass yield estimates are typically obtained using cell counts and measurements of the feed substrate. These quantities are perturbed with measurement noise however. Perhaps most crucially, estimating biomass from cell counts, as needed to assess yields, relies on an assumed cell weight. Noise and discrepancies on these assumptions can lead to significant changes in conclusions regarding a microbes' response. This article proposes a methodology to address these challenges using probabilistic macrochemical models of microbial growth. It is shown that a model can be developed to fully use the experimental data, greatly relax the assumptions on the cell weight, and provides uncertainty estimates of key parameters. These capabilities are demonstrated and validated herein using several case studies with synthetically generated microbial growth data.