Nuppunen-Puputti Maija, Kietäväinen Riikka, Purkamo Lotta, Rajala Pauliina, Itävaara Merja, Kukkonen Ilmo, Bomberg Malin
VTT Technical Research Centre of Finland Ltd., 02044 Espoo, Finland.
Geological Survey of Finland, 02151 Espoo, Finland.
Microorganisms. 2020 Dec 29;9(1):64. doi: 10.3390/microorganisms9010064.
Fungi have an important role in nutrient cycling in most ecosystems on Earth, yet their ecology and functionality in deep continental subsurface remain unknown. Here, we report the first observations of active fungal colonization of mica schist in the deep continental biosphere and the ability of deep subsurface fungi to attach to rock surfaces under in situ conditions in groundwater at 500 and 967 m depth in Precambrian bedrock. We present an in situ subsurface biofilm trap, designed to reveal sessile microbial communities on rock surface in deep continental groundwater, using Outokumpu Deep Drill Hole, in eastern Finland, as a test site. The observed fungal phyla in Outokumpu subsurface were Basidiomycota, Ascomycota, and Mortierellomycota. In addition, significant proportion of the community represented unclassified Fungi. Sessile fungal communities on mica schist surfaces differed from the planktic fungal communities. The main bacterial phyla were Firmicutes, Proteobacteria, and Actinobacteriota. Biofilm formation on rock surfaces is a slow process and our results indicate that fungal and bacterial communities dominate the early surface attachment process, when pristine mineral surfaces are exposed to deep subsurface ecosystems. Various fungi showed statistically significant cross-kingdom correlation with both thiosulfate and sulfate reducing bacteria, e.g., SRB2 with fungi
真菌在地球上大多数生态系统的养分循环中发挥着重要作用，但其在大陆深部地下环境中的生态和功能仍不为人知。在此，我们报告了首次在大陆深部生物圈中观察到云母片岩上有活跃的真菌定殖，以及在前寒武纪基岩中500米和967米深处的地下水中原位条件下深部地下真菌附着在岩石表面的能力。我们展示了一种原位地下生物膜捕集器，它被设计用于揭示大陆深部地下水中岩石表面的固着微生物群落，以芬兰东部的奥托昆普深钻孔作为试验场地。在奥托昆普地下观察到的真菌门有担子菌门、子囊菌门和被孢霉门。此外，群落中有很大一部分代表未分类的真菌。云母片岩表面的固着真菌群落与浮游真菌群落不同。主要的细菌门是厚壁菌门、变形菌门和放线菌门。岩石表面生物膜的形成是一个缓慢的过程，我们的结果表明，当原始矿物表面暴露于深部地下生态系统时，真菌和细菌群落主导了早期的表面附着过程。各种真菌与硫代硫酸盐还原菌和硫酸盐还原菌均呈现出具有统计学意义的跨界相关性，例如，SRB2与真菌。
