During the 2021 Space Life Sciences Training Program, mechanical engineering student Rocky An of Cornell University conducted an independent project using a computer to model the stress responses of microbes to spaceflight microgravity and simulated microgravity. 
Using Computational Fluid Dynamics / Discrete Element Method modeling, Rocky simulated a microbial model community of metabolically cooperative strains of Escherichia coli and Salmonella enterica. His analysis found the greatest difference between microgravity and a microgravity analog facility – a rotating wall vessel (RWV) – or 1 g gravity when species colocalized in dense aggregates.

He also investigated the influence of other features of the system on growth, such as spatial distribution, product yields, and diffusivity. Based on study simulations, he found artificial microgravity to have an amplifying effect on mass transfer and metabolite uptake compared to microgravity and a diminishing impact on sedimentation compared to 1 g gravity. Results indicate that the RWV effect on population growth rate is unclear and specific to the microbial community of study.
For microbes that accompany humans into space, microgravity-induced alterations in the fluid environment are likely to be a major factor in the microbial experience of spaceflight. Computational modeling is needed to investigate how ground-based microgravity simulation methods replicate that experience. This first implementation of CAMDLES demonstrates the importance of a microbial cell’s immediate physical environment on population- and community-level behaviors, especially in the space environment and in experiments meant to simulate the space environment. CAMDLES represents the computational tool capable of providing biologists with unprecedented insight into those interacting physical, chemical, and biological processes.

This research was funded by the Space Life Sciences Training Program and Space Biology.  Rocky An, a student at Cornel University was a Research Associate during the 2021 cohort and worked with Ames Research Center Scientist Dr. Jessica Lee. This research was completed as part of his individual project. The article is available online here.