title: Metagenomic Analysis from the Interior of a Speleothem in Tjuv-Ante's Cave, Northern Sweden.
abstract: Speleothems are secondary mineral deposits normally formed by water supersaturated with calcium carbonate percolating into underground caves, and are often associated with low-nutrient and mostly non-phototrophic conditions. Tjuv-Ante's cave is a shallow-depth cave formed by the action of waves, with granite and dolerite as major components, and opal-A and calcite as part of the speleothems, making it a rare kind of cave. We generated two DNA shotgun sequencing metagenomic datasets from the interior of a speleothem from Tjuv-Ante's cave representing areas of old and relatively recent speleothem formation. We used these datasets to perform i) an evaluation of the use of these speleothems as past biodiversity archives, ii) functional and taxonomic profiling of the speleothem's different formation periods, and iii) taxonomic comparison of the metagenomic results to previous microscopic analyses from a nearby speleothem of the same cave. Our analyses confirm the abundance of Actinobacteria and fungi as previously reported by microscopic analyses on this cave, however we also discovered a larger biodiversity. Interestingly, we identified photosynthetic genes, as well as genes related to iron and sulphur metabolism, suggesting the presence of chemoautotrophs. Furthermore, we identified taxa and functions related to biomineralization. However, we could not confidently establish the use of this type of speleothems as biological paleoarchives due to the potential leaching from the outside of the cave and the DNA damage that we propose has been caused by the fungal chemical etching.
authors.affiliation: Centre for GeoGenetics, University of Copenhagen, Natural History Museum of Denmark, Copenhagen, Denmark.
authors.forename: Marie Lisandra
authors.initials: ML
authors.lastname: Zepeda Mendoza
authors.affiliation: Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lundberg
authors.affiliation: Department of Palaeobiology and the Nordic Center for Earth Evolution (NordCEE), Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Ivarsson
authors.affiliation: Centre for GeoGenetics, University of Copenhagen, Natural History Museum of Denmark, Copenhagen, Denmark.
authors.forename: Paula
authors.initials: P
authors.lastname: Campos
authors.affiliation: Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Johan A A
authors.initials: JA
authors.lastname: Nylander
authors.affiliation: Department of Palaeobiology and the Nordic Center for Earth Evolution (NordCEE), Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Therese
authors.initials: T
authors.lastname: Sallstedt
authors.affiliation: Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Love
authors.initials: L
authors.lastname: Dalen
mesh_terms: D039903:Actinobacteria / Q000235:genetics*; D044822:Biodiversity; D059552:Caves / Q000382:microbiology*; D054892:Metagenome; D056186:Metagenomics; D013548:Sweden