Molecular Microbial Diversity of a Spacecraft Assembly Facility

Abstract

SummaryIn ongoing investigations to map and archive the microbial footprints in various components of the spacecraft and its accessories, we have examined the microbial populations of the Jet Propulsion Laboratory's Spacecraft Assembly Facility (JPL-SAF). Witness plates made up of spacecraft materials, some painted with spacecraft qualified paints, were exposed for ~7 to 9 months at JPL-SAF and examined the particulate materials collected for the incidence of total cultivable aerobic heterotrophs and heat-tolerant (80ºC for 15-min.) spore-formers. The results showed that the witness plates coated with spacecraft qualified paints attracted more dust particles than the non-coated stainless steel witness plates. Among the four paints tested, witness plates coated with NS43G accumulated the highest number of particles, and hence attracted more cultivable microbes. The conventional microbiological examination revealed that the JPL-SAF harbors mainly Gram-positive microbes and mostly spore-forming Bacillus species. Most of the isolated microbes were heat resistant to 80ºC and proliferate at 60ºC. The phylogenetic relationships among 23 cultivable heat-tolerant microbes were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. By 16S rDNA sequence analysis, the isolates fell into seven clades: Bacillus licheniformis, B. pumilus, B. cereus, B. circulans, Staphylococcus capitis, Planococcus sp. and Micrococcus lylae. In contrast to the cultivable approach, direct DNA isolation, cloning and 16S rDNA sequencing analysis revealed equal representation of both Gram-positive and Gram-negative microorganisms.

Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection

“…Low nutrient levels, low humidity, frequent cleaning and sterilization procedures pose a threat for all organisms thriving or living in these environments (Venkateswaran et al, 2001). Challenging the survival of microbes is one of the major aims of spacecraft-associated clean rooms: In terms of planetary protection, biological contamination on spacecraft flying to extraterrestrial points of interest has to be controlled (understood and reduced) in order to avoid compromising the integrity of the future life-detection missions on Mars, Titan or other solar bodies (see also : Horneck et al, 2010).…”

Bacillus safensis sp. nov., isolated from spacecraft and assembly-facility surfaces

“…nov. is proposed. The type strain is FO-36b T (=ATCC BAA-1126 T =NBRC 100820 T ).Spacecraft and associated clean-room assembly-facility surfaces harbour an extremely low biomass (La Duc et al, 2003;Venkateswaran et al, 2001), because of stringent maintenance. However, colonization by micro-organisms specifically adapted to such facility conditions, especially those yet to be cultured and/or characterized, is of major concern to those commissioning modern-day space-related experimentation.…”

“…During monitoring of the microbial diversity of spacecraftassociated environments over a period of 5 years (1999)(2000)(2001)(2002)(2003)(2004), Bacillus pumilus was found to be the second most dominant species among the aerobic spore-forming bacteria (the predominant species being Bacillus licheniformis; La Duc et al, 2004a). Several of these B. pumilus isolates have exhibited elevated resistance to H 2 O 2 (Venkateswaran et al, 2001;Kempf et al, 2005) and are thus considered as 'problematic' micro-organisms, since H 2 O 2 is recommended for the bioreduction of spacecraft components.In previous studies using MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) Abbreviation: MALDI-TOF MS, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA and gyrB gene sequences referred to in this communication are given in The bacterial strains examined in this study are shown in Table 1. A total of 13 strains of this novel micro-organism were isolated from spacecraft and assembly-facility surfaces by standard swabbing procedures (Anonymous, 1980;La Duc et al, 2004b) at various times and locations.…”

“…During monitoring of the microbial diversity of spacecraftassociated environments over a period of 5 years (1999)(2000)(2001)(2002)(2003)(2004), Bacillus pumilus was found to be the second most dominant species among the aerobic spore-forming bacteria (the predominant species being Bacillus licheniformis; La Duc et al, 2004a). Several of these B. pumilus isolates have exhibited elevated resistance to H 2 O 2 (Venkateswaran et al, 2001;Kempf et al, 2005) and are thus considered as 'problematic' micro-organisms, since H 2 O 2 is recommended for the bioreduction of spacecraft components.…”

Overview of Methodologies to Sample and Assess Microbial Burden in Low Biomass Environments

“…However, despite rigorous PP protocols and sterilization procedures, studies have indicated that spacecraft assembly facilities and the surfaces of spacecraft are not devoid of microbial life 11), 12), 28) . Microbial bioburden has been demonstrated to be low (ῌ10 2 colony forming units (CFU)/cm 2 ; 11) ), although even low levels of biomass have the potential to foul pristine environments (e.g., other planetary bodies), confound future life detection missions, and possibly a#ect the safety and well being of crews 11), 14), 20) .…”