Investigating Bacterial Co-culture Growth Responses to Simulated Microgravity​

Abstract

With the popularity of space travel increasing, it is important to understand the effects of microgravity on microbial communities as alterations to bacterial interactions can occur. Staphylococcus epidermidis and Escherichia coli are bacteria that are commonly found within human microbiomes. S. epidermidis is a cocci-shaped gram-positive bacterium that is part of the human skin microbiome. However, it can gather on sites of open skin and enter the body leading to an infection. E. coli is a gram-negative rod-shaped bacterium that can be found in the human gut microbiome. The pathogenic strains of E. coli have the potential to cause harmful conditions in humans such as urinary tract and skin infections. Therefore, it is important to study how S. epidermidis and E. coli influence each other while in a co-culture when exposed to simulated microgravity (SMG) because of the potential changes to the microbiomes of long-term space travelers. This can give insight into the effects of bacterial community interaction in microgravity that can influence astronaut health in long-duration spaceflight. The growth dynamics of E. coli and S. epidermidis post-exposure to SMG as pure cultures and in a co-culture were defined in this experiment. The relative gene expression of growth and biofilm-related genes for E. coli and S. epidermidis post-exposure to SMG for 24 hours in a co-culture were measured. The relative gene expression results showed E. coli target genes, luxS and gapA, and S. epidermidis target gene, luxS, were significantly upregulated post-exposure to SMG for 24 hours in a co-culture