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Zusammenfassung:
Volcanism is a primary process of land formation. It provides a model
for understanding soil-forming processes and the role of pioneer
bacteria and/or archaea as early colonizers in those new environments.
The objective of this study was to identify the microbial communities
involved in soil formation. DNA was extracted from soil samples from the
Llaima volcano in Chile at sites destroyed by lava in different
centuries (1640, 1751, and 1957). Bacterial and archaeal 16S rRNA genes
were analyzed using quantitative polymerase chain reaction (qPCR) and
Illumina MiSeq sequencing. Results showed that microbial diversity
increased with soil age, particularly between the 1751 and 1640 soils.
For archaeal communities, Thaumarchaeota was detected in similar
abundances in all soils, but Euryarchaeota was rare in the older soils.
The analysis of bacterial 16S rRNA genes showed high abundances of
Chloroflexi (37%), Planctomycetes (18%), and Verrucomicrobia (10%) in
the youngest soil. Proteobacteria and Acidobacteria were highly abundant
in the older soils (16% in 1640 and 15% in 1751 for Acidobacteria; 38%
in 1640 and 27% in 1751 for Proteobacteria). The microbial profiles in
the youngest soils were unusual, with a high abundance of bacteria
belonging to the order Ktedonobacterales (Chloroflexi) in the 1957 soil
(37%) compared with the 1751 (18%) and 1640 (7%) soils. In this study,
we show that there is a gradual establishment of the microbial community
in volcanic soils following an eruption and that specific microbial
groups can colonize during the early stages of recovery.
