10:00 AM - 10:15 AM
[MIS06-04] Characterization of Microorganisms Thriving in On-land Mud Volcanoes: Analogs of purported Martian Geologic Structures
Mud volcanism (MV) is one of the most intriguing phenomena observed in various geological settings in the world, which is frequently used as an important “window” into the unknown biosphere of underlying strata. There are many features interpreted as MVs on Mars and searching for extant life or biomarkers in the sediments associated with MVs would be of prime interest for the future Mars exploration.
In recent years, MVs on seafloor-beds were preferentially studied to reveal a complex configuration of microbial communities thriving in the methane-rich submarine sedimentary biosphere. On the contrary, active MVs located across on-land sites have been less investigated. Since the origins and the compositions of erupted muddy fluids are very different between land-based and submarine MVs, their impact on the microbial community structure and potential activity can be variable.
Hereby, we characterized microbial communities of two active methane-seeping on-land MVs, Murono and Kamou, in Niigata prefecture, Japan. The 16S rRNA sequencing analysis of those two sites recovered the dominant archaeal taxa affiliated with methanogens. Anaerobic methanotrophs (ANME), with the subgroups ANME-1b and ANME-3, were also recovered from the Murono site albeit a greatly reduced abundance compared to typical submarine MVs. The bacterial taxa affiliated to atribacteria, sulfate-reducing bacteria (SRB), and Fe(III)-reducing bacteria were recovered. SRB and ANME are known to form a syntrophic consortium, which is often found at the sulfate-methane transition zone of submarine MVs where diffused sulfate (SO42-) is constantly enriched from the ocean. Previous investigations speculate that the erupted materials from Murono are originated from the depth range of 3400 m to 4000 m where the Miocene marine strata are found, and we hypothesize that the old sea-related juvenile water is the source of additional sulfur-related components for the hypothesized SRB-ANME consortium at Murono.
In recent years, MVs on seafloor-beds were preferentially studied to reveal a complex configuration of microbial communities thriving in the methane-rich submarine sedimentary biosphere. On the contrary, active MVs located across on-land sites have been less investigated. Since the origins and the compositions of erupted muddy fluids are very different between land-based and submarine MVs, their impact on the microbial community structure and potential activity can be variable.
Hereby, we characterized microbial communities of two active methane-seeping on-land MVs, Murono and Kamou, in Niigata prefecture, Japan. The 16S rRNA sequencing analysis of those two sites recovered the dominant archaeal taxa affiliated with methanogens. Anaerobic methanotrophs (ANME), with the subgroups ANME-1b and ANME-3, were also recovered from the Murono site albeit a greatly reduced abundance compared to typical submarine MVs. The bacterial taxa affiliated to atribacteria, sulfate-reducing bacteria (SRB), and Fe(III)-reducing bacteria were recovered. SRB and ANME are known to form a syntrophic consortium, which is often found at the sulfate-methane transition zone of submarine MVs where diffused sulfate (SO42-) is constantly enriched from the ocean. Previous investigations speculate that the erupted materials from Murono are originated from the depth range of 3400 m to 4000 m where the Miocene marine strata are found, and we hypothesize that the old sea-related juvenile water is the source of additional sulfur-related components for the hypothesized SRB-ANME consortium at Murono.