RESULTS
The testing of ISS cabin surfaces occurred in 2 phases using various combinations of Contact
Slides and LOCAD-PTS with Gram-negative bacteria (LAL), fungi (beta-glucan), and Gram-
positive bacteria (LTA) cartridges. The first
phase involved extensive swabbing and
sampling of limited sites with both
cartridges and contact slides (like Petri
dishes). When LAL cartridges were used with
contact slides, low levels of endotoxin were
found at 5 sites with the cartridges and at 3
sites with the contact slides. When beta-
glucan and LTA cartridges were used with
contact slides, low levels of fungi were
detected on the beta-glucan cartridges, no
bacteria or fungi colonies grew on the
contact slides, and very low levels of
endotoxin were on the LTA cartridges. The
very low values were expected because the
cartridges produced for this study had a lower sensitivity to its targeted microbial cells than the
other 2 cartridges. The results for this phase were not expected to correlate because the
cartridges measure the presence of both live and dead microbes, and the slides measure live
microorganisms; more so, results were expected to generate a bigger picture of
microorganisms present at different sites. The second phase involved a single swab using
cartridges only of various crew-selected sites expected to have high microbial growth.
Moderate to high levels of endotoxin were observed at sites mostly associated with exercise,
hygiene and dining facilities, where microbial nutrients such as sweat, food remnants, and
water were generally present. A surprising observation from both phases was that endotoxin
was distributed throughout the ISS, despite previous indications that most bacteria on ISS
surfaces were Gram-positive. Lastly, parallel analysis of at least 1 site with all 3 cartridges and
contact slides was performed. Although the values from all 3 cartridges were different from
each other, the majority of the results were still low or very low. Analysis of all the data
collected from the LOCAD-PTS experiments showed 31 samples had low or absent levels of
endotoxin, and 11 samples had moderate to high levels at sites with frequent crew contact,
demonstrating that most surfaces on the ISS are relatively free of microbial molecules (Maule
2009; Morris 2012).
PUBLICATION(S)
Morris HC, Damon M, Maule JG, Monaco LA, Wainwright NR. Rapid culture-independent
microbial analysis aboard the International Space Station (ISS) stage 2: Quantifying 3 Microbial
Biomarkers. Astrobiology. September 2012;12(9):830-840. doi: 10.1089/ast.2012.0863.
Maule JG, Wainwright NR, Steele A, Gunter DL, Morris H, Monaco L. Rapid monitoring of
bacteria and fungi aboard the International Space Station. 47th Aerospace Sciences Meeting
and Exhibit, Orlando, FL; 2009.
Expedition 14 Flight Engineer Suni Williams uses the
swabbing unit to collect samples that will be placed into
the cartridges to be analyzed by the Lab-on-a-Chip
Application Development reader.