Scale-down for scale-up: using CFD to investigate microenvironment conditions and inform experimental design

Large-scale bioreactors play a critical part in strengthening the bioeconomy and developing biotechnology-related industries. As these systems grow from laboratory- to industrial-scale, increasingly complex fluid dynamics impact microbial performance, making yields harder to predict and crippling economic viability. Computational fluid dynamics can be used to investigate these large-scale systems and inform scale-down experimental design strategies for targeting quantities of interest. To this end, we use a multiphase solver developed within OpenFOAM that couples multicomponent transport and reaction processes specific to the organism P. putida through Metabolic and Gene Expression (ME) modeling. We investigate the formation of microenvironments at the large scale pertaining to shear, oxygen, and pH and quantify the high-stress zones experienced at the microbial level. We then explore potential small-scale equivalence for quantities of interest that can then be used to devise targeted experiments to further investigate stressor impacts on microbial yield.