Space Flight Conditions Drive Functional Reorganization and Selection for Taxonomically Dominant Groups in Microbial Communities of Diabetic Foot Ulcers

Abstract

With the growing role of space flight in biomedical research, it is imperative to gain insight into astronaut health and space conditions pertaining to the microbiota. The phenomenon of skin damage due to drying in space resembles that of foot ulcers in diabetic individuals. Past research has investigated the compositional changes and differences in diversity between diabetic foot ulcer samples sent to space and on Earth, but the functionality of the microorganisms remains unknown. Thus, this study aims to elucidate the differences between space flight and ground control diabetic foot ulcer samples through analyses of alpha and beta diversity, taxonomic composition, and functional profile. Alpha diversity analyses revealed that space flight samples had greater diversity in relation to richness and evenness of the community, but lower diversity due to phylogenetic distance. Beta diversity analyses suggested that microbial communities exposed to space flight were less diverse in genetic relatedness but did not demonstrate differences in richness nor evenness. Taxonomic composition analysis illustrated that the dominant taxa in the space flight condition were the Proteobacteria phylum, broken down into the Xanthomonadaceae and Pseudomonadaceae families, and finally into the Pseudomonas and Stenotrophomonas genera. Finally, functional analysis revealed significantly altered pathways related to increased pathways for adaptations to low-nutrient environments in space flight relative to ground control. Overall, the results confirmed a functional reorganization of the microbial communities likely resulting from stressors that are induced during space flight.