Abstract EANA2025-130

Volcanic and hydrothermal environments on Earth are important analogues for potential habitable niches on icy moons and other planetary bodies. In this study, we collected environmental samples from shallow submarine hydrothermal vents on the island of Panarea (Italy) to investigate the presence of thermophilic methanogenic archaea adapted to extreme conditions. The samples were enriched anaerobically within an anaerobic chamber under strictly controlled conditions [1]. The samples were used to inoculate a modified DSMZ 141 medium under a H₂/CO₂ atmosphere at 60°C and 80°C [2]. Successful enrichment cultures of methanogens were validated through methane production analysis using a gas chromatograph and the detection of methanogenic cell autofluorescence at 420 nm under UV light using an epifluorescent microscope. Several distinct morphotypes were observed, including small cocci, short or long straight rods, and curved rods with a terminal spore-like (“golf-shaped”). All showing the blue autofluorescence typical for the F420 co-factor of methanogenic cells. These enrichment cultures could be purified by plating on a thermostable solid medium. The new methanogenic strains representing candidate new species are currently being characterized.  A primary objective of this ongoing research is to isolate pure thermophilic archaeal colonies using solid agar media —a crucial but challenging step, considering the strict anoxic and thermophilic requirements of these organisms.

We present our initial successful approach to achieving visible colony formation on solid media at 60 °C, which offers a promising foundation for the future isolation and characterization of novel thermophilic methanogens derived from volcanic systems, marking an important milestone in cultivating these extremophiles outside of the commonly practiced liquid enrichment. This ongoing work contributes to refining techniques for isolating extremophilic archaea from volcanic systems and supports the development of earth analogues for biosignature detection in astrobiological exploration.

References

1.Hanišáková, N.; Vítězová, M.; Rittmann, S.K.-M.R. The Historical Development of Cultivation Techniques for Methanogens and Other Strict Anaerobes and Their Application in Modern Microbiology. Microorganisms 2022, 10, 412. https://doi.org/10.3390/microorganisms10020412.

 

2. Hanišáková N, Vítězová M, Vítěz T, Kushkevych I, Kotrlová E, Novák D, Lochman J and Zavada R (2023) Microbiological insight into various underground gas storages in Vienna Basin focusing on methanogenic Archaea. Front. Microbiol. 14:1293506. doi: 10.3389/fmicb.2023.1293506