Microbial Dynamics Across Commercial Spaceflights of Varying Duration

Krishnavajhala, A.; Gingras, M.-C.; Santiago-Rodriguez, T.; Chen, Y.; Bandaranaike, D.; Bhamidipati, S.; Xiang, Q.; Kottapalli, K.; Momin, Z.; Santhanam, A.; Walker, K.; Wang, Q.; Griffin, S. M.; Masternak, M. M.; Ross, M. C.; Muzny, D.; Wu, J.; Urquieta, E.; Gibbs, R.; doddapaneni, H.

doi:10.64898/2026.05.29.728784

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bioRxiv · 10.64898/2026.05.29.728784

Microbial Dynamics Across Commercial Spaceflights of Varying Duration

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Abstract

SummarySpaceflight introduces environmental stressors that can alter human microbiomes and immune responses. We analyzed 259 biospecimens from six astronauts across two commercial ISS missions: Axiom 2 (10-day mission) and Axiom 3 (21-day mission). Samples included saliva, stool, urine, and body swabs from 10 anatomical sites, profiled via 16S ribosomal RNA (rRNA) gene sequencing. Gut and oral microbiomes remained stable, while skin-associated communities exhibited transient diversity shifts post-flight. Taxonomic analysis revealed individual and site-specific patterns as well as a possible microbial acquisition from the ISS/space-flight environment and microbiome exclusivity. Cytokine profiling from single cell data indicated immune activation, with IL-32 and IL-16 elevated in Axiom 2 and Axiom 3, coinciding with microbial changes. These findings provide an integrated view of microbiome individuality, exclusivity and immune dynamics during two short-duration commercial spaceflights of three weeks, informing strategies for crew health on future long-duration missions.

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Krishnavajhala, A., Gingras, M.-C., Santiago-Rodriguez, T., Chen, Y., Bandaranaike, D., Bhamidipati, S., Xiang, Q., Kottapalli, K., Momin, Z., Santhanam, A., Walker, K., Wang, Q., Griffin, S. M., Masternak, M. M., Ross, M. C., Muzny, D., Wu, J., Urquieta, E., Gibbs, R., doddapaneni, H.. 2026-05-30. Microbial Dynamics Across Commercial Spaceflights of Varying Duration. https://doi.org/10.64898/2026.05.29.728784

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