Higher Microbial Biomass Accumulation on El Médano 464 Meteorite Compared with Adjacent Soils in the Atacama Desert.

IF 2.6 3区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS
Astrobiology Pub Date : 2025-02-01 DOI:10.1089/ast.2024.0071
Gabriel A Pinto, María Ángeles Lezcano, Laura Sanchéz-García, Rodrigo Martínez, Víctor Parro, Daniel Carrizo
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引用次数: 0

Abstract

Chondritic meteorites can be appropriate substrates for the colonization of terrestrial microorganisms. However, determining whether organic compounds are intrinsic to the meteorite or come from external (terrestrial) contamination is still controversial. This research explores the molecular distribution and carbon isotopic composition of three lipid families (hydrocarbons, alkanoic acids, and alcohols) as well as DNA extracted from the interior of a CO carbonaceous chondrite named El Médano 464 (EM 464), discovered in the Atacama Desert in 2019. Three soil samples from the discovery area of EM 464 were collected and used as a background control for the composition and distribution of organic compounds. Our results revealed a higher abundance of the three lipid families in EM 464 compared with the surrounding soil samples. The organic compounds in EM 464 showed a mean δ13C value of -27.8 ± 0.5 for hydrocarbons (N = 20), -27.6 ± 1.1 for alkanoic acids (N = 17), and -27.5 ± 2.2‰ for alcohols (N = 18). These δ13C-depleted values are compatible with terrestrial biosignatures and are within isotopic values produced as a result of carbon fixation due to the Calvin cycle (δ13C of ca. from -19 to -34‰) widely used by photosynthetic terrestrial microorganisms. The DNA analysis (based on the bacterial 16S rRNA gene) showed a dominance of Proteobacteria (now Pseudomonadota) and Actinobacteriota in both meteorite and soils but exhibited different bacterial composition at the family level. This suggests that the microbial material inside the meteorite may have partially come from the adjacent soils, but we cannot rule out other sources, such as windborne microbes from distant locations. In addition, the meteorite showed higher bacterial diversity (H' = 2.4-2.8) compared with the three soil samples (H' = 0.3-1.8). Based on the distribution and δ13C value of organic compounds as well as DNA analysis, we suggest that most, if not all, of the organic compounds detected in the studied CO chondrite are of terrestrial origin (i.e., contamination). The terrestrial contamination of EM 464 by a diverse microbial community indicates that Atacama chondrites can offer distinctive ecological conditions for microorganisms to thrive in the harsh desert environment, which can result in an accumulation of microbial biomass and preservation of molecular fossils over time.

与邻近土壤相比,阿塔卡马沙漠El m 464陨石上微生物生物量积累更高。
球粒陨石可以作为陆地微生物定植的适宜基质。然而,确定有机化合物是陨石固有的还是来自外部(陆地)污染仍然存在争议。这项研究探索了三种脂质家族(碳氢化合物、烷酸和醇)的分子分布和碳同位素组成,以及从2019年在阿塔卡马沙漠发现的名为El m达诺464 (EM 464)的CO碳质球粒陨石内部提取的DNA。从EM 464发现区收集了3个土壤样品,作为有机化合物组成和分布的背景对照。我们的结果显示,与周围土壤样品相比,EM 464中三个脂质家族的丰度更高。EM 464有机化合物的平均δ13C值为烃类(N = 20) -27.8±0.5‰,烷烃(N = 17) -27.6±1.1‰,醇类(N = 18) -27.5±2.2‰。这些δ13C耗尽值与陆地生物特征相一致,并且在陆地光合微生物广泛使用的卡尔文循环(ca的δ13C从-19‰到-34‰)所产生的碳固定的同位素值范围内。基于细菌16S rRNA基因的DNA分析显示,在陨石和土壤中均以变形菌门(现为假单胞菌门)和放线菌门占优势,但在科水平上表现出不同的细菌组成。这表明陨石内的微生物物质可能部分来自邻近的土壤,但我们不能排除其他来源,比如来自遥远地方的风传微生物。此外,陨石细菌多样性(H′= 2.4 ~ 2.8)高于3种土壤样品(H′= 0.3 ~ 1.8)。根据有机化合物的分布和δ13C值以及DNA分析,我们认为大多数(如果不是全部的话)在研究的CO球粒陨石中检测到的有机化合物是陆源的(即污染)。EM 464受到多种微生物群落的陆地污染表明,阿塔卡马球粒陨石可以为微生物在恶劣的沙漠环境中茁壮成长提供独特的生态条件,这可能导致微生物生物量的积累和分子化石的保存。
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来源期刊
Astrobiology
Astrobiology 生物-地球科学综合
CiteScore
7.70
自引率
11.90%
发文量
100
审稿时长
3 months
期刊介绍: Astrobiology is the most-cited peer-reviewed journal dedicated to the understanding of life''s origin, evolution, and distribution in the universe, with a focus on new findings and discoveries from interplanetary exploration and laboratory research. Astrobiology coverage includes: Astrophysics; Astropaleontology; Astroplanets; Bioastronomy; Cosmochemistry; Ecogenomics; Exobiology; Extremophiles; Geomicrobiology; Gravitational biology; Life detection technology; Meteoritics; Planetary geoscience; Planetary protection; Prebiotic chemistry; Space exploration technology; Terraforming
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