Alteration of Bacillus Subtilis DNA Architecture in Space: Global Effects on DNA Supercoiling, Methylation, and the Transcriptome (BRIC-26)

The investigation will support the first in-depth evaluation of DNA structure for a microbe cultured in spaceflight. The work will provide a deeper understanding how the spaceflight environment can generate cellular outcomes that can in turn affect the greater health of the exploration ecosystem. This work pioneer's scientific discovery in the field of microbiology and supports the ability for crew to thrive in the deep space environment.

Delivery to the International Space Station via the SpaceX-26 Commercial Resupply Service mission.

Studying the response of microbial cells to the spaceflight environment is a high priority in space biology, due to the importance of microbes in maintaining the health of astronauts and their habitats. Previous ISS flight experiments (missions BRIC-18, -21, and -23) using the Gram-positive model bacterium Bacillus subtilis have uncovered global changes in the transcriptome, an altered mutagenic spectrum of DNA, and significant differences in cell susceptibility to fluoroquinolone antibiotics in spaceflight vs. ground controls. Fluoroquinolone antibiotics target the enzymes DNA gyrase and topoisomerase IV, which are critical for maintaining DNA supercoiling as well as nucleoid compaction and conformation.

Spaceflight environment stimuli, which could be chemical or mechanical, may invoke changes in DNA architecture and affect many downstream genetic events such as: epigenetic DNA modifications (i.e., the methylome); the location of mutagenic hotspots in DNA; and global gene transcription patterns (i.e., the transcriptome). The proposed microbial model of this process draws from the example of the eukaryotic signal transduction cascade, where a cellular receptor transduces a signal to the area of genetic material, and the cell responds by altering genome conformation, methylation and supercoiling states. The research team of this investigation looks to characterize this model for a prokaryote as such alterations are thought to result in an altered global transcription pattern (the transcriptome), which in turn modifies metabolic pathways leading to a phenotypic response.

Aside from being a Gram-positive model bacterium for studies on physiology and metabolism, B. subtilis, is a common gut bacterium and is also used as a cell factory to produce chemicals enzymes and antimicrobial materials. Therefore, understanding how the bacteria responds to the spaceflight environment will contribute to our understanding of how to support crew health and paves the way for harnessing the bacterium’s industrial power for space exploration applications.

The study will not only help to build a spaceflight model to understand how external stimuli affect bacterial phenotype but will also build this model for an Earth-based ground control. Thus, a comprehensive model will result for B. subtilis that will link genetic alternations to phenotypic outcomes.

Space Station Research Explorer