The biogeographic pattern of microbial communities inhabiting terrestrial mud volcanoes across the Eurasian continent

Abstract

Abstract. Terrestrial mud volcanoes (MVs) represent the surface expression of conduits tapping fluid and gas reservoirs in the deep subsurface. Such plumbing channels provide a direct, effective means to extract deep microbial communities fueled by geologically produced gases and fluids. The drivers accounting for the diversity and composition of these MV microbial communities, which are distributed over a wide geographic range, remain elusive. This study characterized the variation in microbial communities in 15 terrestrial MVs across a distance of ∼ 10 000 km on the Eurasian continent to test the validity of distance control and physiochemical factors in explaining biogeographic patterns. Our analyses yielded diverse community compositions with a total of 28 928 amplicon sequence variances (ASVs) taxonomically assigned to 73 phyla. While no true cosmopolitan member was found, ∼ 85 % of ASVs were confined within a single MV. Community variance between MVs appeared to be higher and more stochastically controlled than within MVs, generating a slope of the distance–decay relationship exceeding those for marine seeps and MVs as well as seawater columns. For comparison, physiochemical parameters explained 12 % of community variance, with the chloride concentration being the most influential factor. Overall, the apparent lack of fluid exchange renders terrestrial MVs a patchy habitat, with microbiomes diverging stochastically with distance and consisting of dispersal-limited colonists that are highly adapted to the local environmental context.

Impact of persistently high sea surface temperatures on the rhizobiomes of Zostera marina in a Baltic Sea benthocosms

“…Spirochaetacea are key degraders and decomposers of complex organic material commonly found in the seagrass rhizosphere (Wang et al., 2021). In the summer, Marinilabiliaceae were found to be the main degraders in Z. marina roots, as they can metabolize different forms of organic carbon (Conte et al., 2023; Tu et al., 2022). Unlike the ambient setup, that early temperature effect has also stimulated the sulfur cycle throughout the setup, with a stronger increase of sulfate reducers as temperature increases.…”

Peloplasma aerotolerans gen. nov., sp. nov., a Novel Anaerobic Free-Living Mollicute Isolated from a Terrestrial Mud Volcano

“…The information on anaerobic organoheterotrophic fermentative microorganisms, isolated from TMVs, is limited to a few reports [11,12]. Representatives of the class Mollicutes have been detected by molecular methods based on a microbial community analysis in several TMVs [13,14]; however, to date, no cultivated Mollicutes from mud volcanoes are known. The Taman Peninsula is among the regions with the most pronounced mud volcanism; the Kerch-Taman mud volcano province includes over 100 active TMVs [15].…”

Phenotypic and genomic characterization of the first alkaliphilic aceticlastic methanogens and proposal of a novel genus Methanocrinis gen.nov. within the family Methanotrichaceae

“…Although most hydrocarbon gases released from TMVs are thermogenic, sometimes emission of biogenic methane can reach 20% of the total methane (Etiope et al, 2009 ). The archaeal part of the TMVs microbial communities usually contains many anaerobic methane-oxidizing archaea (ANME) and a small number of methanogens (Alain et al, 2006 ; Niederberger et al, 2010 ; Merkel et al, 2021 ; Tu et al, 2022 ). Mud volcanic fluids of the Kerch–Taman region often have high pH values due to a presence of sodium carbonates (Lavrushin et al, 2021 ).…”