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Astrobiology assesses the habitability of planetary bodies and the potential for extraterrestrial life. Analog environments on Earth serve as sites for studying extreme environments that resemble extraterrestrial conditions, aiding in validating life-detection methods, mission instrumentation, and biosignature preservation. These environments function as a source of model microorganisms and communities that define the habitability and biochemistry of such extraterrestrial environments. Well-known analog environments include the Atacama Desert (Chile) for space mission validation, the McMurdo Dry Valleys (Antarctica) for Mars analog studies, and Rio Tinto (Spain) for extreme acidic environments. Although significant research has been conducted on these sites, various alternative environments may also offer valuable opportunities for astrobiological studies. Saudi Arabia encompasses a variety of pristine (or with minimal anthropic influence) extreme environments with conditions analogous to extraterrestrial settings (e.g., deserts and salt flats as analogs to Mars, and terrestrial and marine volcanic fields as analogs to icy moons), yet their potential remains largely unexplored. Recent studies have identified a volcanic crater with sodium phosphates and chlorates that mimics Enceladus’s ocean chemistry, and researchers have cultured Halalkalibacterium halodurans strains with adaptations to survive these conditions, offering valuable biological models. Additionally, complex metabolic landscapes with implications for icy moon habitability have been observed in Red Sea systems, which could be employed as valuable natural laboratories in astrobiological research. Furthermore, these findings underscore the potential of the Saudi Arabian extremophilic microbiome for space-related research. This review explores the microbial diversity of extreme environments in Saudi Arabia, emphasizing their potential as new terrestrial analogs to Mars and icy moons and the role of their microbiomes as terrestrial proxies for extraterrestrial life.

In this study, we explored for the first time the glass-forming ability of Martian regolith simulants using the melt-quenching process in a resistive furnace under ambient air, assessing their potential for ISRU-based glass production in space exploration. Dark-colored glasses were successfully synthesized for four different compositions. The glassy state is confirmed by X-ray diffraction and characteristic thermal events, observed in differential scanning calorimetry. The glass compositions were analyzed by X-ray fluorescence, indicating minimal loss compared to the original regolith simulant minerals. The thermal and physical parameters were consistent with literature on silicate glasses. Raman spectroscopy revealed different structural conformations among the various glass compositions. Reflectance and photoacoustic measurements showed very strong absorption through UV to NIR (250–1200 nm). The analyzes revealed low UV reflectances (approximately 5%), while visible and infrared differences certainly arise from compositional variations that affect optical properties and coloration. These findings demonstrate the feasibility of producing glass from Martian soil, shedding light on new possibilities for future challenges and research in the space exploration field.

Iron-rich minerals, such as hematite (α-Fe2O3), are prominent constituents of the Martian surface; they are considered to be potential indicators of past aqueous activity and habitability. This study investigated the interaction between the extremophilic black fungus Rhinocladiella similis LaBioMMi 1217 and hematite under simulated laboratory conditions on Mars, focusing on redox-mediated dissolution processes, metabolic adaptations, and biosignature formation. The fungus was cultivated with powdered and polished hematite substrates, and mineral alteration was monitored through physicochemical measurements and scanning electron microscopy (SEM). Genome mining was performed to identify and map genes involved in iron metabolism. The metabolic profile of the fungus under hematite treatment was assessed via untargeted metabolomics. Over 15 days, the cultures exhibited marked acidification (pH decreased from 7.0 to 4.7) and a 10-fold increase in the dissolved Fe2+ ion concentration (26–270 mg/L), indicating metabolically driven iron reduction. SEM revealed surface etching and localized roughening consistent with microbially induced weathering, whereas these changes were absent in the abiotic controls. Genes linked to siderophore biosynthesis (sidA, sidC, sidD, sidF, sidH, sidI, and sidL) and reductive iron assimilation (FET3, FTR1, and FRE1) were identified. Untargeted metabolomics confirmed the secretion of organic acids, iron-chelating siderophores (e.g., ferrichrome C), and redox-active aromatic compounds in the presence of hematite, supporting a multifaceted strategy that combines acidification, chelation, and redox mediation. Collectively, these results show that the fungus actively promotes hematite dissolution through organic molecule-mediated mechanisms. Such interactions hold astrobiological relevance, as fungal modification of hematite might lead to the production of diagnostic chemical and mineralogical biosignatures, informing future life-detection strategies on Mars.

The fungus Talaromyces fuscoviridis was isolated from soil collected in a copper-mine tailings basin in Pará State, Brazil, an extreme environment that can induce the production of bioactive secondary metabolites. Extracts and fractions obtained after cultivation were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (LC–HRMS) and compared using Global Natural Products Social molecular networking (GNPS), which revealed a family of seven putative polyunsaturated steroids. Isolation led to the characterization of two major steroids: the known Ergosta-3(4),5(6),7(8),14(15),22(23)-pentaene (1a) and a previously unreported metabolite, Ergosta-5(6),7(8),14(15),22(23)-tetraen-3-ol (2a). Their structures were elucidated through comprehensive spectroscopic and spectrometric methods (e.g., UV–Vis, NMR, and high-resolution mass spectrometric [HRMS]), with the structure of steroid 2a being unequivocally confirmed by single-crystal x-ray diffraction (SCXRD). Notably, the biosynthesis of these steroids was significantly enhanced when the cultivation medium was supplemented with manganese chloride (MnCl2). Furthermore, the steroids were tested for their in vitro antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical using an adapted UHPLC–DAD method, showing over 80% of the scavenging capacity of β-carotene at the lowest tested concentrations.

Studying the survival of terrestrial microorganisms under Martian conditions, particularly in the presence of perchlorates, provides crucial insights for astrobiology. This research investigates the resilience of the extremophile black fungus Rhinocladiella similis to magnesium perchlorate and UV-C radiation. Results show R. similis, known for its tolerance to acidic conditions, exhibits remarkable resistance to UV-C radiation combined with perchlorate, as well as to high concentrations of magnesium perchlorate, surpassing Exophiala sp. strain 15Lv1, a eukaryotic model organism for Mars-like conditions. Growth curve analyses revealed both strains can thrive in perchlorate concentrations mimicking Martian perchlorate-rich environments, with R. similis adapting better to higher concentrations. Morphological and protein production changes were investigated, and mass spectrometry identified perchlorate-induced proteins, advancing molecular understanding of potential microbial life on Mars. These findings advance knowledge of extremophile capabilities, contributing to the search for life beyond Earth and informing the design of future Martian rovers equipped for biosignature detection.