Filter debris from the Spacelab module D-2 of STS-55 was analyzed for microbial contamination. Debris from cabin and avionics filters was collected by Kennedy Space Center personnel on May 8, 1993, 2 days postflight. Debris weights were similar to those of previous Spacelab missions. Approximately 5.1E+5 colony forming units per gram of debris were enumerated from the cabin and avionics filter debris, respectively. these numbers were similar in previous missions for which the entire contents were analyzed without sorting of the material. Bacterial diversity was small compared to previous missions, with no gram negative bacteria isolated. Only one bacterial species, Corynebacterium pseudodiphtheriticum, was not isolated previously by the laboratory from Spacelab debris. This organism is a normal inhabitant of the pharynx. A table listing all species of bacteria isolated by the laboratory from previous Spacelab air filters debris collection is provided

Huff, T. L.

English

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NASA CONTRACTOR
REPORT
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NASA CR- 193883
MICROBIOLOGICAL ANALYSIS OF DEBRIS FROM SPACE
TRANSPORTATION SYSTEM (STS)-55 SPACELAB D-2
By T.L. Huff
Sverdrup Technology, Inc.
Huntsville, Alabama 35806
January1994
Final Report
Prepared for
NASA-Marshall Space Flight Center
Marshall Space Flight Center, Alabama 35812
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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE .t. REPORT TYPE AND DATES COVERED
January 1994 Contractor Report - Final Report
4. TITLE AND SUBTITLE S. FUNDING NUMBERS
Microbiological Analysis of Debris From Space Transportation System
(STS)-55 Spacelab D-2
6. AUTHOR(S)
T.L. Huff
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
Sverdrup Technology, Inc.
Huntsville, Alabama 35806
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
National Aeronautics and Space Administration
Washington, DC 20546
NAS8-37814
8. PERFORMING ORGANIZATION
REPORT NUMBER
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
NASA CR-193883
I1. SUPPLEMENTARY NOTES
Technical Monitor: Dr. Elizabeth Rodgers
Materials and Processes Laboratory, Science and Engineering Directorate
George C. Marshall Space Flight Center, MSFC, Alabama 35812
12a. DISTRIBUTION/AVAILABILITY STATEMENT
Unclassifled-Unllmlted
12b. DISTRIBUTION CODE
13. ABSTRACT (Maximum 200 words)
Filter debris from the Spaeelab module D--2 of STS-55 was analyzed for microbial contamina-
tion. Debris from cabin and avionics f'dters was collected by Kennedy Space Center personnel on May
8, 1993, 2 days postflight. Debris weights were similar to those of previous Spacelab missions. Ap-
proximately 5.1E+6 and 1.7E+5 colony forming units per gram of debris were enumerated from the
cabin and avionics filter debris, respectively. These numbers were similar in previous missions for
which the entire contents were analyzed without sorting of the material. Bacterial diversity was small
compared to previous missions, with no gram negative bacteria isolated. Only one bacterial species,
Corynebacterium pseudodiphtheriticum, was not isolated previously by the laboratory from Spacelab
debris. This organism is a normal inhabitant of the pharynx. A table listing all species of bacteria
isolated by the laboratory from previous Spacelab air filter debris collection is provided.
14. SUBJECTERMS
bacteria, microbiology, Spacelab, air contamination, air filters
17. SECURITYCLASSIFICATION18. SECURITYCLASSIFICATION19. SECURITYCLASSIFICATION
OFREPORT OF THISPAGE OF ABSTRACT
Unclassified Unclassified Unclassified
15. NUMBER OF PAGES
lO
16. PRICE CODE
NTIS
20. LIMITATION OF ABSTRACT
Unlimited
NSN 7540-01-280-5500 Standard Form 298 (Rev 2-89)

TABLE OF CONTENTS
INTRODUCTION ............................................ 1
METHODS ................................................. 1
RESULTS ................................................. 1
DISCUSSION .............................................. 2
REFERENCES .............................................. 3
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INTRODUCTIOH
As part of an on-going study to determine the microbial content
in the avionics and cabin environments of shuttle spacelab
missions, air filter debris from STS-55, Spacelab-D2, was
examined. Data gathered from these flights also provides
information on the microbial diversity in air that may be
expected during long-term missions.
In addition to reporting the results of the current analysis, a
comparison with the 3 previous flights is presented. These
flights included: STS-40,SLS-I; STS-42,IML-1; STS-49, SLJ. Debris
weights, microbial counts and bacterial species identified from
these flights are compared.
_THODS
Debris from the cabin and avionics filters was collected by
Kennedy Space Center personnel on May 8, 1993, 2 days post-
flight. Collection procedures have been described previously
(1). Samples were delivered to the Microbial Ecology Facility
housed in the Analytical and Physical Chemistry Branch of the
Materials and Processes Laboratory at Marshall Space Flight
Center approximately 8 days following shuttle landing,
The debris from the avionics and cabin filters was aseptically
transferred to tared, sterile 500 ml polypropylene bottles and
the debris weight recorded. A 100 ml volume of sterile phosphate
buffered saline (PBS) was added to each bottle containing the
debris and the contents sonicated for 15 minutes. After settling
for I0 minutes, 1 ml of the cabin slurry was diluted as necessary
in sterile PBS, and spread-plated on duplicate R2A plates. The
avionics slurry was processed similarly. In an attempt to
increase recovery of different bacterial species, aliquots of
each sample were also inoculated initially in sterile 3% brain
heart infusion broth (BHI) for 3 days at 28C. After this time,
samples were diluted as appropriate, and spread-plated on R2A.
All R2A plates were incubated at 28C for 7 days.
Identification of morphologically distinct bacterial colonies was
determined by subculturing isolates onto trypticase soy agar
(TSA) and/or Biolog Universal Growth Medium (BUGM) in preparation
for identification using Minitek and Biolog microbial
identification systems, respectively.
RESULTS
The total debris weight for the cabin and avionics debris was
5.84 grams and 3.46 grams, respectively. Table 1 is a comparison
of debris weight between this flight and previous flights where
total debris collected from the filters was analyzed by the
laboratory. The debris weights for these 3 missions were similar.
Approximately 5 x 106 colony forming units/gram debris (cfu/g)
were recovered from the cabin debris slurry plated directly onto
R2A agar. The avionics sample slurry plated directly onto R2A
contained 1.7 x 10 u cfu/g. A comparison in microbial numbers to
STS-49, SLJ, which was also examined using unsorted material, is
shown in Table 2. There was no significant difference observed
between the two missions.
Table 3 lists the bacterial species recovered from the cabin and
avionics samples. The cabin debris sample plated directly on R2A
agar consisted entirely of Staphylococcus aureus. The BHI-treated
cabin sample contained no Staphylococcus but instead consisted of
Bacillus sp. and Corynebacterium pseudodiphtheriticum. Four (4)
species of Staphylococcus were recovered from the avionics debris
sample plated directly on R2A agar. Bacillus sp. and Micrococcus
luteus were also recovered from this sample. The only bacterial
species recovered from the avionics debris sample incubated in
BHI broth prior to plating on R2A agar was Staphylqc0ccus aure_s,
which was also recovered by the direct plating method. All
species had been recovered in the laboratory from previous
spacelab missions except Cqrynebacterium pseudodiphtheriticu_m, a
non-pathogenic bacterium normally isolated from the human
pharynx.
Table 4 lists the bacterial species recovered by the laboratory
from both the current and previous three spacelab missions.
Greater bacterial diversity was found in STS 42, IML-I and STS
49, SLJ, where the laboratory received all debris from the
filters, compared to the partial collection in STS 40, SLS-1.
Cabin filter debris from these three missions contained greater
microbial diversity than the corresponding avionics filter
debris.
In contrast, avionics filter debris from the current mission
contained greater microbial diversity than the cabin filter
debris. However, neither sample contained the diversity found in
the IML-1 and SLJ missions, where total debris was also analyzed.
The IML-1 and SLJ missions averaged 12 species in the cabin
debris compared to 3 for the current mission. These previous
missions also averaged 9 distinct species in avionics debris
compared to 6 for this flight. This reduction in diversity in
both cabin and avionics samples appears largely due to the
absence of gram negative bacteria, which had been isolated on all
previous missions by the laboratory.
DISCUSSION
Debris weights for both cabin and avionics samples were similar
to those recorded in the 2 previous mis@ions !IML-I and SLJ),
from which the laboratory received the entire debris collected
from the filters. Post-flight analysis time was also similar for
the 3 missions with analysis from this mission beginning 8 days
following shuttle landing compared to 6 and 7 days for IML-I and
SLJ flights, respectively.
2
Total numbers of bacteria per gram of debris were also comparable
to STS-49, SLJ, the only other mission from which the laboratory
received the entire filter debris collected and analyzed the
contents unsorted.
The use of BHI to improve recovery of bacterial species was
inconclusive. This method appeared effective in recovery of
distinct species from the avionics debris but not cabin debris.
In the avionics debris sample, 6 distinct species were isolated
in the BHI-inoculated sample. Only 1 species was isolated from
direct plating onto R2A agar, and this species was also found in
the BHI-inoculated sample. A total of three distinct species
were isolated from cabin samples, two from the BHI broth samples
and one from direct plating onto R2A agar.
Overall bacterial diversity was small in both cabin and avionics
debris samples in comparison to previous missions, largely due to
the absence of gram negative bacteria. Because debris weights
and processing times were similar for all 3 missions where the
total debris was analyzed, it is unlikely that the absence of
gram negative bacteria represents an actual decrease in these
bacteria in both cabin and avionics air systems during the
flight. It is more likely that environmental changes such as
excess heat and drying during transport to the laboratory led to
the loss of the gram negative population.
Only one bacterial species, ¢orynebacterium pseudodiphtheri_iGum,
has not been isolated from previous spacelab missions by the
laboratory. This organism is a normal inhabitant of the pharynx.
_S
1. Summary of Reports Detailing Analysis of Debris Collected From
SLS-1 Fan Filters in June and July, 1991. E.B. Rodgers
and M.C. Roman, NASA/MSFC, Huntsville, AL 35812.
3
TABLE 1
Comparison of Avionics and Cabin Debris
Weights Between Spacelab Flights
MISSION DEBRIS WEIGHT (GRAMS)
CABIN AVIONICS
STS-42, IML-I 8.51 2.3
STS-49, SLJ 3.61 4.69
STS-55, D-2 5.84 3.46
TABLE 2
Comparison in Microbial Numbers Between
STS-49, SLJ and STS-55, D-2
MISSIQN COLONY FORMING UNITS/GRAM DEBRIS
CABIN AVIONICS
STS-49, SLJ
STS-55, D-2
7.7E+6 7.6E+4
5.1E+6 1.7E+5
4
TABLE 3
Bacterial Species Recovered From Cabin
and Avionics Debris Using R2A and BHI Broth
CABIN
R2A
Staphylococcus aureus
BHI Broth
Bacillus
Coryn_b_acterium pseudodiphtheriticum
AVIONICS
R2A
Staphylococcus aureu@
Staphylococcus
Staphylococcus e id rmidi
Staphyl0coccu$ cohnii
Micrococcu$ luteu$
Bacill_
BHI Broth
Staphylococcus aureus
5
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APPROVAL
MICROBIOLOGICAL ANALYSIS OF DEBRIS FROM SPACE
TRANSPORTA_ON SYSTEM (STS)--55 SPACELAB D--2
By Timothy L. Huff
The information in this report has been reviewed for technical content. Review of any informa-
tion concerning Department of Defense or nuclear energy activities or programs has been made by the
MSFC Security Classification Officer. This report, in its entirety, has been determined to be unclassified.
P.I .SCaR [
Director,Maibria_ and ProcessesLaboratory
U.S. GOVERNMENT PRINTING OFFICE 1994 533--108/00026
7



Microbiological analysis of debris from Space Transportation System (STS)-55 Spacelab D-2

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