Identification of Microorganisms Isolated from Mars-Bound Spacecraft Using MALDI-TOF

Abstract

The primary goal of the Biotechnology and Planetary Protection Group (BPPG) at the Jet Propulsion Laboratory (JPL) is to prevent microbial contamination between Earth and other planetary bodies. This helps preserve the ability to study other worlds as they exist in their natural states and protects our biosphere from extraterrestrial life. The process for identifying microbes located on space-bound hardware in JPL can be more efficient and precise by using the technique called matrix-assisted laser desorption and ionization time of flight (MALDI-TOF). Once this identification technique is fully implemented, the process time will be reduced from two weeks to one hour, and the cost will be reduced by a factor of five. The MALDI-TOF database contains 5,989 microorganism profiles, but because it was created with microbes found in a clinical setting, it was only comprehensive enough to identify 7% of JPL isolates. This called for the need of our own unique in-house MALDI database composed of the complete array of our microbial diversity. This database was created using bacterial isolates with known 16S rRNA sequences collected from various Mars mission hardware from the last 40 years. A mass spectral profile (MSP) was created and archived for each isolate, so in the future, unknown isolates can be identified by running them against the database using real time classification (RTC). After identifying 288 new operational taxonomic units (OTUs), a rarefaction curve was created which estimated that after studying 500 additional isolates our database will be comprehensive. During the summer of 2016, all stages of the MSP creation process were continued to finish constructing the JPL microbial database

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