Rapid Colonization of a Space‐returned Ryugu Sample by Terrestrial Microorganisms
The presence of microorganisms within meteorites has been used as evidence for extraterrestrial life, however, the potential for terrestrial contamination makes their interpretation highly controversial.
Here, we report the discovery of rods and filaments of organic matter, which are interpreted as filamentous microorganisms, on a space-returned sample from 162173 Ryugu recovered by the Hayabusa 2 mission. The observed carbonaceous filaments have sizes and morphologies consistent with microorganisms and are spatially associated with indigenous organic matter.
The abundance of filaments changed with time and suggests the growth and decline of a prokaryote population with a generation time of 5.2 days. The population statistics indicate an extant microbial community originating through terrestrial contamination.
The discovery emphasizes that terrestrial biota can rapidly colonize extraterrestrial specimens even given contamination control precautions.
The colonization of a space-returned sample emphasizes that extraterrestrial organic matter can provide a suitable source of metabolic energy for heterotrophic organisms on Earth and other planets.
Electron microscope images of sample A0180. (a) A backscattered electron image (BEI) showing a matrix dominated by phyllosilicate with framboidal (fM) and spheroidal (sM) magnetite, dolomite (D), and sulfide (S). Areas containing abundant organic matter (OM) are present. (b) A BEI of rods and filaments (RF) on the surface of the specimen. (c) A secondary electron image (SEI) showing the detailed morphology of filaments with indents denoting individual cells. (d) A SEI of the cavity shown containing an organic rod structure. (e) A BEI showing cluster of rods and filaments around a dolomite grain. A cylindrical mold (MD) is also present. (f) A carbon Kα map of the image shown in e illustrating that filaments are carbon-rich (RF) and showing a C-rich rim on the dolomite grain. The contrast of the map has been enhanced using a linear filter. All pixels with an intensity of >50% are saturated (g) A secondary electron image showing highly elongate filaments. (i) A BEI of a dolomite grain surrounded by matrix containing abundant organic matter. A cluster of filaments is also present. Images were obtained on the November 11, 2022 (a–d), November 30, 2022 (g, h), and the January 14, 2023 (e, f) — Meteoritics & Planetary Science.
Rapid colonization of a space‐returned Ryugu sample by terrestrial microorganisms – Genge – Meteoritics & Planetary Science – Wiley Online Library (open access)
Astrobiology
