Ultradeep microbial communities at 4.4 km within crystalline bedrock : implications for habitability in a planetary context
MetadataShow full item record
The deep bedrock surroundings are an analog for extraterrestrial habitats for life. In this study, we investigated microbial life within anoxic ultradeep boreholes in Precambrian bedrock, including the adaptation to environmental conditions and lifestyle of these organisms. Samples were collected from Pyhäsalmi mine environment in central Finland and from geothermal drilling wells in Otaniemi, Espoo, in southern Finland. Microbial communities inhabiting the up to 4.4 km deep bedrock were characterized with phylogenetic marker gene (16S rRNA genes and fungal ITS region) amplicon and DNA and cDNA metagenomic sequencing. Functional marker genes (dsrB, mcrA, narG) were quantified with qPCR. Results showed that although crystalline bedrock provides very limited substrates for life, the microbial communities are diverse. Gammaproteobacterial phylotypes were most dominant in both studied sites. Alkanindiges -affiliating OTU was dominating in Pyhäsalmi fluids, while different depths of Otaniemi samples were dominated by Pseudomonas. One of the most common OTUs detected from Otaniemi could only be classified to phylum level, highlighting the uncharacterized nature of the deep biosphere in bedrock. Chemoheterotrophy, fermentation and nitrogen cycling are potentially significant metabolisms in these ultradeep environments. To conclude, this study provides information on microbial ecology of low biomass, carbon-depleted and energy-deprived deep subsurface environment. This information is useful in the prospect of finding life in other planetary bodies.
Purkamo , L , Kietäväinen , R , Nuppunen-Puputti , M , Bomberg , M & Cousins , C 2020 , ' Ultradeep microbial communities at 4.4 km within crystalline bedrock : implications for habitability in a planetary context ' , Life , vol. 10 , no. 1 , 2 . https://doi.org/10.3390/life10010002
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
DescriptionFunding: Wihuri Foundation postdoctoral research grant (L.P.); KYT2018 and KYT2022 grants (RENGAS and BIKES) (R.K.); Royal Society of Edinburgh Research Fellowship to C.C; COST Action Life-ORIGINS (TD1308) funded the short-term scientific mission for to visit ETH Zürich to perform qPCR analyses (L.P.).
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.