Abstract
The bacterial and archaeal community composition and the
possible carbon assimilation processes and energy sources
of microbial communities in oligotrophic, deep,
crystalline bedrock fractures is yet to be resolved. In
this study, intrinsic microbial communities from
groundwater of six fracture zones from 180 to 2300g m
depths in Outokumpu bedrock were characterized using
high-throughput amplicon sequencing and metagenomic
prediction. Comamonadaceae-, Anaerobrancaceae- and
Pseudomonadaceae-related operational taxonomic units
(OTUs) form the core community in deep crystalline
bedrock fractures in Outokumpu. Archaeal communities were
mainly composed of Methanobacteriaceae-affiliating OTUs.
The predicted bacterial metagenomes showed that pathways
involved in fatty acid and amino sugar metabolism were
common. In addition, relative abundance of genes coding
the enzymes of autotrophic carbon fixation pathways in
predicted metagenomes was low. This indicates that
heterotrophic carbon assimilation is more important for
microbial communities of the fracture zones. Network
analysis based on co-occurrence of OTUs revealed possible
"keystone" genera of the microbial communities belonging
to Burkholderiales and Clostridiales. Bacterial
communities in fractures resemble those found in
oligotrophic, hydrogen-enriched environments.
Serpentinization reactions of ophiolitic rocks in
Outokumpu assemblage may provide a source of energy and
organic carbon compounds for the microbial communities in
the fractures. Sulfate reducers and methanogens form a
minority of the total microbial communities, but OTUs
forming these minor groups are similar to those found in
other deep Precambrian terrestrial bedrock environments.
Original language | English |
---|---|
Pages (from-to) | 3091-3108 |
Journal | Biogeosciences |
Volume | 13 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2016 |
MoE publication type | A1 Journal article-refereed |
Keywords
- archaea
- bacteria (microorganisms)
- burkholderiales
- clostridiales
- comamonadaceae
- methanobacteriaceae
- otus
- pseudomonadaceae