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Guðmundur Óli Hreggviðsson
Strategic Scientist
gudmundo@matis.is
Biodiversity in hot springs at Þeistareykir and Gjástykki / Biodiversity in hot springs at Þeistareykir and Gjástykki
The project was part of an environmental assessment for the planned geothermal utilization and involved a study of the ecosystem in the hot springs at Þeistareykir and Gjástykki. A total of 27 samples were taken. Temperatures and acidity at the sampling points ranged from 33-96 ° C to pH 1.9-8.6. The species composition of the micro-organisms and their proportions were determined by nucleic acid amplification and sequencing of the 16S rRNA species-determining gene using bacterial and antimicrobial markers. A total of 21 bacteria and / or ancient bacteria were detected in 21 samples. DNA sequences were classified into species according to 98% affinities and compared with Genbank sequences for species analysis. In acidic hot springs at Þeistareykir, species within the bacterial assemblages β-, δ-, and γ-Proteobacteria and Aquificae were most common, especially acidic and / or primitive species that use sulfur and iron compounds and bind CO2. In vapors in lava caves at Þeistareykir at higher acidity levels (pH 6.7-8.6), the species Acidobacteria, Actinobacteria, Chloroflexi and Deinococcus-Thermus were prominent. Deinococcus-Thermus and Verrucomicrobium were the most common in samples from the hot springs in Gjástykki (pH 4.4-6.9). Many of these species are non-primitive. Ancient bacteria were found mainly in acidic areas at Þeistareykir, and in all samples from Gjástykki, but not in steam eyes in lava at Þeistareykir, as the acidity level is higher there. Species within the Crenarchaeota group were found in all of these samples, but species within the Euryarchaeota were bound to samples from the surface formations and acid soils. Most ancient bacteria can live primitive life. Biodiversity (Nt / Nmax) bacteria was most often between 1-3 and 1-2 among ancient bacteria. These low values are typical of peripheral ecosystems, where one species is in a very high proportion. Numerous new species were found in the samples, especially bacteria in steam eyes in lava at Þeistareykir and in hot springs in Gjástykki. Also, species of Euryarchaeota within ancient bacteria often showed a low kinship percentage and are therefore considered new species.
Due to future plans for utilizing the geothermal power at Þeistareykir and Gjástykki, an environmental assessment of the biodiversity in hot springs from these sites was carried out. A total of 27 samples were taken from various sites at temperatures of 33-96 ° C and pH 1.9-8.6. The species composition and ratios of thermophiles were estimated by PCR and sequencing of the 16S rRNA genes using bacterial and archaeal primers. Microbial species were detected in 21 samples. DNA sequences were grouped at the 98% similarity species level and compared with available sequences in Genbank for species determination. Species belonging to the bacterial phyla of β-, δ-, and γ-Proteobacteria and Aquificae were dominating in samples from the solfatara fields of Þeistareykir. These were mainly acidophiles and autotrophs capable of utilizing sulfur- and iron compounds and fixing CO2. A totally different pattern of species composition was observed in samples from fumaroles at the lava fields of Þeistareykir at higher pH (6,7-8,6) than in the solfataras. These were mainly Acidobacteria, Actinobacteria, Chloroflexi and DeinococcusThermus. In Gjástykki, (pH 4.4-6.9) Deinococcus-Thermus and Verrucomicrobium sp. were dominating. These are mainly heterotrophs. Archeal species were found as well in the solfatara fields at Þeistareykir and also in hot springs at Gjástykki, but not in the high pH fumaroles at Þeistareykir lava fields. Species from the Crenarchaeota group were found in the samples, but species belonging to the Euryarchaeota group were only detected in solfatara soil samples and sulfur / iron precipitates. These were mainly autotrophs. Biodiversity (Nt / Nmax) was calculated for all samples and estimated at 1-3 among the Bacteria and 1-2 among the Archaea. These low values are typical for extreme environments where one species is highly dominating. Many novel species were found in the samples, especially in soil from fumaroles at the lava field at Þeistareykir and in hot springs at Gjástykki. Euryarchaeal species within the Archaea domain often showed low similarity to known species and most likely represent new species.