title: High-density 16S microarray and clone library-based microbial community composition of the Phoenix spacecraft assembly clean room.
abstract: The bacterial diversity and comparative community structure of a clean room used for assembling the Phoenix spacecraft was characterized throughout the spacecraft assembly process by using 16S rRNA gene cloning/sequencing and DNA microarray (PhyloChip) technologies. Samples were collected from several locations of the clean room at three time points: before Phoenix's arrival (PHX-B), during hardware assembly (PHX-D), and after the spacecraft was removed for launch (PHX-A). Bacterial diversity comprised of all major bacterial phyla of PHX-B was found to be statistically different from PHX-D and PHX-A samples. Due to stringent cleaning and decontamination protocols during assembly, PHX-D bacterial diversity was dramatically reduced when compared to PHX-B and PHX-A samples. Comparative community analysis based on PhyloChip results revealed similar overall trends as were seen in clone libraries, but the high-density phylogenetic microarray detected larger diversity in all sampling events. The decrease in community complexity in PHX-D compared to PHX-B, and the subsequent recurrence of these organisms in PHX-A, speaks to the effectiveness of NASA cleaning protocols. However, the persistence of a subset of bacterial signatures throughout all spacecraft assembly phases underscores the need for continued refinement of sterilization technologies and the implementation of safeguards that monitor and inventory microbial contaminants.
authors.affiliation: Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA. vaishamp@jpl.nasa.gov
authors.forename: Parag
authors.initials: P
authors.lastname: Vaishampayan
authors.forename: Shariff
authors.initials: S
authors.lastname: Osman
authors.forename: Gary
authors.initials: G
authors.lastname: Andersen
authors.forename: Kasthuri
authors.initials: K
authors.lastname: Venkateswaran
mesh_terms: D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification*; D004780:Environment, Controlled; D004866:Equipment Contamination / Q000517:prevention & control / Q000706:statistics & numerical data; D015723:Gene Library; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D018531:Spacecraft / Q000295:instrumentation*
chemical_list: D012336:RNA, Ribosomal, 16S