Assembly of Bacterial Genome Sequences from Metagenomes of Spacecraft Assembly Cleanrooms

Ilieva, Velislava; Steel, Bruce; Pratscher, Jennifer; Olsson-Francis, Karen; Macey, Michael C.

doi:10.1128/mra.01439-20

Cited by 1 publication

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“…Although the extensive cleaning processes limit the number of microbes capable of withstand such clean room conditions, hardy spore-forming microorganisms like Amycolatopsis methanolica (also a methylotrophic bacteria) [58], Actinoplanes friuliensis, and Geodermatophilus obscurus, demonstrate the capacity of certain taxa to survive sterilization processes. However, it is important to identify and assembly microorganisms that may be actively growing [59]. To measure the microbial growth rate we used Growth Rate Index (GRiD), a bioinformatic tool able to work with low-quality genome assemblies even at 0.05% relative abundances of 100 bp × 10 million reads.…”

Section: Discussionmentioning

confidence: 99%

A comprehensive metagenomics framework to characterize organisms relevant for planetary protection

et al. 2021

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Background Clean rooms of the Space Assembly Facility (SAF) at the Jet Propulsion Laboratory (JPL) at NASA are the final step of spacecraft cleaning and assembly before launching into space. Clean rooms have stringent methods of air-filtration and cleaning to minimize microbial contamination for exoplanetary research and minimize the risk of human pathogens, but they are not sterile. Clean rooms make a selective environment for microorganisms that tolerate such cleaning methods. Previous studies have attempted to characterize the microbial cargo through sequencing and culture-dependent protocols. However, there is not a standardized metagenomic workflow nor analysis pipeline for spaceflight hardware cleanroom samples to identify microbial contamination. Additionally, current identification methods fail to characterize and profile the risk of low-abundance microorganisms. Results A comprehensive metagenomic framework to characterize microorganisms relevant for planetary protection in multiple cleanroom classifications (from ISO-5 to ISO-8.5) and sample types (surface, filters, and debris collected via vacuum devices) was developed. Fifty-one metagenomic samples from SAF clean rooms were sequenced and analyzed to identify microbes that could potentially survive spaceflight based on their microbial features and whether the microbes expressed any metabolic activity or growth. Additionally, an auxiliary testing was performed to determine the repeatability of our techniques and validate our analyses. We find evidence that JPL clean rooms carry microbes with attributes that may be problematic in space missions for their documented ability to withstand extreme conditions, such as psychrophilia and ability to form biofilms, spore-forming capacity, radiation resistance, and desiccation resistance. Samples from ISO-5 standard had lower microbial diversity than those conforming to ISO-6 or higher filters but still carried a measurable microbial load. Conclusions Although the extensive cleaning processes limit the number of microbes capable of withstanding clean room condition, it is important to quantify thresholds and detect organisms that can inform ongoing Planetary Protection goals, provide a biological baseline for assembly facilities, and guide future mission planning.

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Section: Discussionmentioning

confidence: 99%