Ivarsson Magnus, Schnürer Anna, Bengtson Stefan, Neubeck Anna
Department of Palaeobiology and Nordic Center for Earth Evolution, Swedish Museum of Natural History Stockholm, Sweden.
Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences Uppsala, Sweden.
Front Microbiol. 2016 May 12;7:674. doi: 10.3389/fmicb.2016.00674. eCollection 2016.
The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type of organism with attributes of geobiological significance not previously accounted for. Anaerobic fungi are best known from the rumen of herbivores where they produce molecular hydrogen, which in turn stimulates the growth of methanogens. The symbiotic cooperation between anaerobic fungi and methanogens in the rumen enhance the metabolic rate and growth of both. Methanogens and other hydrogen-consuming anaerobic archaea are known from subseafloor basalt; however, the abiotic production of hydrogen is questioned to be sufficient to support such communities. Alternatively, biologically produced hydrogen could serve as a continuous source. Here, we propose anaerobic fungi as a source of bioavailable hydrogen in the oceanic crust, and a close interplay between anaerobic fungi and hydrogen-driven prokaryotes.
近期对大洋火成岩地壳中真菌的认识，挑战了将该环境仅视为原核生物环境的理解，并促使人们重新思考深部生物圈的生态学。火成岩地壳中的缺氧区域丰富，且随地壳年龄和深度增加。深海沉积物和海底存在厌氧真菌，这引入了一种具有此前未被考虑到的地质生物学意义属性的生物体。厌氧真菌在食草动物瘤胃中最为人所知，它们在瘤胃中产生分子氢，进而刺激产甲烷菌的生长。瘤胃中厌氧真菌与产甲烷菌之间的共生合作提高了两者的代谢率和生长速度。产甲烷菌和其他消耗氢气的厌氧古菌在海底玄武岩中也有发现；然而，氢气的非生物产生是否足以支持此类群落受到质疑。另外，生物产生的氢气可以作为持续的来源。在此，我们提出厌氧真菌是大洋地壳中生物可利用氢的一个来源，并且厌氧真菌与氢驱动的原核生物之间存在密切的相互作用。
