Open AccessCharacterization of bacterial diversity to a depth of 1500 m in the Outokumpu deep borehole, Fennoscandian Shield
Author(s) -
Itävaara Merja,
Nyyssönen Mari,
Kapanen Anu,
Nousiainen Aura,
Ahonen Lasse,
Kukkonen Ilmo
Publication year - 2011
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2011.01111.x
Subject(s) - borehole , biology , firmicutes , library , temperature gradient gel electrophoresis , 16s ribosomal rna , bacteria , paleontology
This paper demonstrates the first microbiological sampling of the Outokumpu deep borehole (2516 m deep) aiming at characterizing the bacterial community composition and diversity of sulphate‐reducing bacteria (SRB) in Finnish crystalline bedrock aquifers. Sampling was performed using a 1500‐m‐long pressure‐tight tube that provided 15 subsamples, each corresponding to a 100‐m section down the borehole. Microbial density measurements, as well as community fingerprinting with 16S rRNA gene‐based denaturing gradient gel electrophoresis, demonstrated that microbial communities in the borehole water varied as a function of sampling depth. In the upper part of the borehole, bacteria affiliated to the family Comamonadaceae dominated the bacterial community. Further down the borehole, bacteria affiliated to the class Firmicutes became more prominent and, according to 16S rRNA gene clone libraries, dominated the bacterial community at 1400–1500 m. In addition, the largest number of bacterial classes was observed at 1400–1500 m. The dsr B genes detected in the upper part of the borehole were more similar to the dsr B genes of cultured SRBs, such as the genus Desulfotomaculum , whereas in the deeper parts of the borehole, the dsr B genes were more closely related to the uncultured bacteria that have been detected earlier in deep earth crust aquifers.