Phenotypic Changes Exhibited by E. coli Cultured in Space

Area of Science:

• Astrobiology
• Microbiology
• Space Science

Background:

• Bacteria are essential for human space exploration.
• Understanding bacterial adaptation to microgravity is crucial for long-duration space missions.

Purpose of the Study:

• To investigate phenotypic changes in Escherichia coli cultured in microgravity.
• To assess the impact of gentamicin sulfate concentration on bacterial growth in space.

Main Methods:

• Culturing Escherichia coli on the International Space Station and Earth.
• Challenging cultures with varying gentamicin sulfate concentrations.
• Analyzing cell count, size, envelope thickness, ultrastructure, and morphology using microscopy techniques.

Main Results:

• A 13-fold increase in final cell count was observed in spaceflight samples.
• Space-grown E. coli exhibited resistance to normally inhibitory gentamicin sulfate levels.
• Cells in microgravity were smaller (37% of control volume) with thicker cell envelopes (25-43% increase).
• Outer membrane vesicles were present in spaceflight samples, and cells formed aggregates.

Conclusions:

• Microgravity significantly alters Escherichia coli phenotype, including growth, drug resistance, cell size, and envelope structure.
• Observed changes suggest altered molecule-cell interactions and potential for enhanced biofilm formation in space.
• These findings are critical for managing bacterial behavior in future space missions.