Controlling Bacteria In Space

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Controlling Bacteria In Space
Daniel Blustein Kalamazoo College Nona Hinkle
and Ami Smith Bionetics Corporation NASA-
Kennedy Space Center
http//www.uga.edu
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Overview

• Preventing the spread of bacteria throughout
  the solar system and protecting the health of
  human space travelers are
• important issues that
• require the control of
• microbes in spacecraft.
• A silane quaternary
• ammonium salt (QAS)
• was applied to aluminum
• and tested against three
• species of bacteria to determine its value as
  an antimicrobial surface shield.

NASA
JPL
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MethodsAluminum coupons were treated with the
ÆGIS Microbe ShieldTM and the antimicrobial
agents effectiveness was examined. For one
hour, treated and untreated coupons were
independently exposed to three types of bacteria
Bacillus subtilis, Staphylococcus epidermidis and
Escherichia coli. Bacterial growth was recorded
using the pour-plate method.
ResultsFor B. subtilis and S. epidermidis, the
numbers of live bacteria were greatly reduced
when exposed to the coupons treated with the QAS.
The results were inconclusive for E. coli. The
effectiveness of the QAS surfacing agent appeared
to decline after repeated uses as evidenced by a
decreased bacterial killing.
The pour-plate method using tryptic soy agar.
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Acknowledements
Conclusion
The results from the B. subtilis and S. epidermis
correlated with the expected antimicrobial
effects of the QAS. E. coli, however, was less
affected by the treatment. This result is most
likely explained by the loss of effectiveness of
the QAS after repeated uses. As the aluminum
coupons were reused and autoclaved between uses,
the activity of the microbe shield seemed to be
reduced. This finding is contrary to the company
claim that the QAS is non-leaching and permanent.
It is supposed to withstand temperatures well
over the autoclaving temperature of 121C. The
surface darkened after autoclaving in the spent
media, suggesting that some sort of change
occurred on the metal.
Thank you to Randall Sumner and the Environmental
Microbiology Laboratory at Kennedy Space Center
for assistance and advice in the preparation of
this project. Thank you to Jason Johns and Arvye
Davis for laboratory assistance and to Adam
Santone and Dr. Daniel Woodard for their guidance.
Setup for surface test and preparation of the
initial bacteria concentrations.
Flasks in agitator at T0 for surface test