Michael Doyle

1
Effects of Microgravity and Spaceflight on
Bacteria

• Michael Doyle

2
Questions

• What are the limitations of this research?
• What effects were seen in E. coli and S.
  typhimurium when grown in a LSMMG environment?

3
Methods

• Due to the nature of space, there are limited
  ways to study effects of microgravity on bacteria
  when on Earth
• High Aspect Rotating Vessel (HARV) simulates a
  Low-Shear Modeled Microgravity(LSMMG) environment
  that mimics some of the same factors in space

4
Limitations

• Limitations to the power, weight and times year
  spaceflights occur, experiments are done
  infrequently
• Large financial burden
• Due to gravity, limitations to the actual
  interactions with the experiment have to be very
  controlled to avoid contamination

5
Importance of this Research

• Astronaut health
• Maintenance and care of equipment
• New environment, new possibilities
• Commercial Applications

6
Conditions

• Low gravity
• Similar environments on earth are found in the
  brush border of the microvilli of epithelial
  cells and in utero
• Increased radiation
• Nutrient uptake

7
Effects of Microgravity on E. coli

• Increased conjugal transfer rates
• Acid tolerance, flagellar and chemotactic genes
  were up regulated
• Increased tolerance to osmotic pressures and
  acidic environments

8
Effects of microgravity on S. typhimurium

• Lethal dose required to kill mice was 5.2 times
  lower
• Could be due to increased acid stress tolerance
• Implications for Space

9
Effects of microgravity on S. typhimurium

• Increased survival rates in the infection of cell
  layers containing macrophages
• Survived at a higher rate short term, long term
  they did not
• Can not be attributable to an enhanced ability to
  coloniz and penetrate epithelial cells

10
Hfq

• RNA chaperone that binds to sRNA and mRNA found
  in several bacteria including S. typhimurium
• Expression decreased during spaceflight
• Negative regulator of tra operon
• Could lead to increased conjugation rates,
  increased tolerances

11
Other changes

• Biofilms, as well as different strains of
  bacteria developed higher antibiotic resistances
• Immune system suppression
• Spore production
• Increased production of antibiotics in some
  fungus