Development of a Custom MALDI-TOF MS Database for Species-Level Identification of Bacterial Isolates Collected From Spacecraft and Associated Surfaces

Abstract

Since the 1970s, the Planetary Protection Group at the Jet Propulsion Laboratory (JPL) has maintained an archive of spacecraft-associated bacterial isolates. Identification of these isolates was routinely performed by sequencing the 16S rRNA gene. Although this technique is an industry standard, it is time consuming and has poor resolving power for some closely related taxa. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry is widely used in clinical diagnostics and is a promising method to substitute standard 16S rRNA sequencing. However, manufacturer-provided databases lack the bacterial diversity found in spacecraft-assembly cleanrooms. This study reports the development of the first custom database of MALDI-TOF MS profiles of bacterial isolates obtained from spacecraft and associated cleanroom environments. With the use of this in-house database, 454 bacterial isolates were successfully identified in concurrence with their 16S rRNA sequence-based classifications. Additionally, MALDI-TOF MS resolved strain-level variations, identified potential novel species and distinguished between members of taxonomic groups, which is not possible using conventional 16S rRNA sequencing. MALDI-TOF MS has proved to be an accurate, high-throughput approach for real-time identification of bacterial isolates during the spacecraft assembly process.

Effects of anEnterococcus faecium‐based probiotic on growth performance and health of Pirarucu,Arapaima gigas

“…The bacteria E. faecium was isolated from healthy A. gigas , selected by in vitro assays by our research group according to Mouriño et al (), identified by MALDI‐TOF mass spectrometry (Microflex) (Seuylemezian et al, ), with identification confirmed using a molecular approach by Neoprospecta microbiome technologies (Santa Catarina State, Brazil). This study was approved by an Ethics Committee for Animal Experimentation (CEUA/172008FAPESPA01).…”

Mihaliç Peynirlerinden İzole Edilen Propionibacterium Türlerinin MALDI-TOF MS ile Tanımlanması

“…Although molecular methods have failed up to separate P. freudenreichii subspecies, MALDI-TOF analysis has been successful method for characterization of intraspecific differences (subspecies, strains) (Vorob'eva et al, 2011). Because MALDI-TOF MS provides more detailed protein profile than what is signified by the 16S rRNA gene, it can detect strain-level differences among isolate samples (Seuylemezian et al, 2018). The MALDI spectra of the samples revealed that there were characteristic protein groups belong to Propionibacterium as marker biomolecules (Vorob'eva et al, 2011); therefore, they can be differentiated easily.…”

Acid and aluminium-tolerant microbes isolated from China space station assembly cleanroom surfaces and identified by 16S rRNA/ITS sequencing and MALDI-TOF MS

“…The standard contained a carefully manufactured extract of this microorganism that shows a characteristic peptide and protein profile in MALDI-TOF MS spectra. The detected spectrum peaks correspond to the mass of the most abundant proteins in a sample which turns out to be specific for the analysed microbial species (Singhal et al ., 2015; Seuylemezian et al ., 2018). Thus, identification occurs automatically using software Bruker Biotyper MS version 3 which is responsible to compare the spectral profile of tested microorganism with a reference database DB 7311.…”