Impact Of Simulated Microgravity In Short-term Evolution Of An RNA Bacteriophage

Introduction

Microgravity is a critical environmental factor in space that can alter microbial physiology and virus–host interactions. Understanding these effects is essential for planetary protection and crew health during long-term missions. Bacteriophage Qβ, an RNA virus infecting Escherichia coli F+ strains, provides a relevant model due to its potential presence in the human gut microbiome and its well-characterized evolutionary dynamics.

Methods

We simulated microgravity using a custom-built 3D-clinostat and compared Qβ infections in semisolid medium under standard gravity and simulated microgravity. Twelve evolutionary lines were propagated for ten serial transfers under four experimental conditions combining bacterial growth and infection environments. Viral titers were quantified by plaque assay, and consensus sequences were determined by Sanger sequencing.

Results

Initial infections under simulated microgravity yielded significantly lower viral titers than those in standard gravity, likely due to hindered phage diffusion and delayed infection initiation. After ten transfers, mutation C2011A (amino acid substitution T222N in the A1 virus protein) was fixed in all lines evolved under simulated microgravity but remained absent or polymorphic in standard gravity lines. Under simulated microgravity, the mutation increased virus titers and promoted faster initiation of infections in semisolid medium. However, those effects were not appreciable in normal gravity.

Discussion

Our findings highlight the adaptability of Qβ and the potential impact of microgravity on phage-host interactions, offering insights into virus evolution in extraterrestrial conditions and its implications for space missions and planetary protection.

Design and dimensions of the 3D-clinostat. (A) Photograph of the custom-built 3D-clinostat, consisting of an aluminum cylinder (48.5 cm long, 6 cm radius) mounted on a rectangular frame that rotates around two perpendicular axes. Two independent motors drive rotation at adjustable speeds, enabling the cylinder to traverse all orientations on a sphere and simulate microgravity conditions. Dimensions of the main components are indicated. (B) Detailed view of the cylinder’s dimensions and configuration. Up to 16 Petri dishes can be stacked inside the cylinder, and culture tubes can be inserted longitudinally along its lateral surface. — Frontiers

• Impact of simulated microgravity in short-term evolution of an RNA bacteriophage, Frontiers via PubMed (open access)
• Impact of simulated microgravity in short-term evolution of an RNA bacteriophage, Frontiers (open access)

Astrobiology, space biology, microbiology, virology,