5. Origin of Exomicrobiology
Search for microbes in space has been linked to
Astrobiology.
In fact Astro microbiology was created due to Cold War.
First attempt NASA's Viking program in the 1975, in
which two Mars landers searched for biosignatures of
life on Mars.
The results were largely inconclusive.
6. For future space applications such as the quest of
microbial fuel cells. Eg, Methanogens
To develop a life support system that enable humans to
live outside the earth’s environment. Eg, MELiSSA
Biotechnological processes that are successfully used
on earth could be employed on space. Eg, Bio mining.
7. WHAT do we know ?
No proof of any
extraterrestrial microbial life
has been found naturally.
Check the mutation and
survival of microbes after
their deliberate exposure to
outer space.
8. How ?
Space can effect microbes in two
ways:
1: By Weakening the microbe
(leads to death)
2: By Strengthening the microbe
(leads to resistant form)
9. Planetary Exploration
Most of the exploration attempts were on Mars due to its
promising environment and close proximity.
Europa, Titan and Enceladus. All either had or have liquid
water.
Titan has liquid hydrocarbons on its surface which may
support life based on these hydrocarbons.
Mars has an atmosphere containing abundant amounts of
carbon and nitrogen, both essential elements needed for
life
10. Extreme conditions in Space
Weightlessness/ Microgravity
Increased radiation exposure
Space Vacuum
Thermal extremes
High velocity micrometeoroids
Space studies on microbes
Effect of basic parameters on microbes
Applied aspects
11. Microbes in Microgravity
Microgravity affect gene expression and growth
kinetics.
Growth is affected by reduction Extracellular mass
transfer and motility.
Microgravity also increase in virulence and Biofilm
production.
Most of the studies related to microgravity are
simulated on earth in devices like clinostat.
12. Physical Effects of microgravity on
microbes
EXTRACELLULAR MASS TRANSFER
Transfer under gravity occurs through diffusion and
convection
Convection is caused by relative densities of molecules
In microgravity, convection is reduced and mass transfer
relies on diffusion only.
This reduction of mass transfer is hypothesized to cause
a decrease in lag phase
13. Physical Effects of microgravity on
microbes
Cell Growth
Cell concentration of E.coli was greater than 1 g.
Presence of gravity leads to sedimentation and over
crowding and rapid nutrient depletion
Within microgravity the microbes are better distributed
and leads to greater proliferation.
14. Physical Effects of microgravity on
microbes
Biofilm production
Adherence is dependent on the forces acting on cell
In microgravity, reduced fluid shear causes (S. aureus and P.
aeroginosa) causes decreased Hfq expression.
Although virulence was decreased but cell adhesion was
enhanced.
Hfq protein is a global post-transcriptional regulator that
plays a key role in gene expression. It results in decrease
secondary metabolite production.
Deletion of the Hfq gene causes loss of secondary
metabolite production
15. Physical Effects of microgravity on
microbes
Cell size
E.coli’s average volume of the spaceflight cells was 37%
of the earth controls.
This reduced cell size was due to lower rate of diffusion
The reduced cell size was also due to altered growth
rate.
16. Physical Effects of microgravity on
microbes
Virulence
Flight-grown S. Typhimurium were more virulent in
mice
The flight-grown S. Typhimurium had a lower lethal
dose (LD50) among the mice.
They also died faster as compared ground mice.
Hfq - a global translational regulator in Salmonella -
was found to be the key factor behind this increased
virulence
17. Exceptions to hyper-virulence and
T3SS
Yersinia pestis and S. aureus have shown exception to
the the trend of microgravity induced hyper virulence.
Yersinia pestis showed diminished proliferation and
virulence, and it had compromised T3SS function.
T3SS( injectosome)
Impairment of T3SS often renders the organism non-
pathogenic
18. List of Microorganisms tested in Outer Space
The survival of some microorganisms exposed to outer space has
been studied using both simulated facilities and low Earth
orbit exposures.
Examples are the following:
Bacteria and Bacterial Spores
Bacteria & bacterial spores Low Earth orbit Simulated conditions
Aeromonas proteolytica
Enterobacter aerogenes
Staphylococcus aureus
Escherichia coli
Bacillus subtilis
21. Future applications
Health assessment: diminish effectiveness of immune
system makes microbes potentially harmful and resistant
for onboard crew.
P. aeruginosa and S. aureus are opportunistic pathogens in
skin flora.
With the advent of antibiotic-resistant strains such as
MRSA, these species in particular can be life-threatening.
Chemotherapeutic purpose: eight special fungi isolated
from the accidental site of nuclear power plant are sent to
space to see if they produce new compounds that could be
used as radiation therapy molecules.
22. Vaccine development: virulance and growth factors can
contribute for the development of vaccines. Astrogenetix’s
space based Salmonella research have been successful in
formation of its vaccine.
Secondary metabolite production: Monorden produce
by fungus humicola was increased. Actinomycin D by
Streptomyces plicatus also increased
Creating habitable environment in outer space:
installing bioreactors on Mars which would run entirely on
cyanobacteria, providing biomaterial to initiate life.
23. References
Artemieva, N. A., and B. A. Ivanov. 2004. Launch of Martian meteorites in oblique impacts. Icarus 171:183–196.
Baker, P. W., M. L. Meyer, and L. G. Leff. 2004. Escherichia coli growth under modeled reduced gravity.
Microgravity Sci. Technol. 15:39–44.
Mothersill, C., and C. B. Seymour. 2004. Radiation-induced bystander effects—implications for
cancer. Nat. Rev. Cancer 4:158–164.
Zea L, Larsen M, Estante F, Qvortrup K, Moeller R, Dias de Oliveira S, Stodieck L and Klaus D (2017)
Phenotypic Changes Exhibited by E. coli Cultured in Space.Front. Microbiol. 8:1598.doi:
10.3389/fmicb.2017.01598
Notas del editor
Space microbiology is still in its infancy, therefore understanding and expanding on it will be critical for astronauts, who have no access to health care facilities and have limited medications during their missions