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Schlagwörter:
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Zusammenfassung:
Microorganisms can potentially colonise volcanic rocks using the
chemical energy in reduced gases such as methane, hydrogen (H-2) and
carbon monoxide (CO). In this study, we analysed soil metagenomes from
Chilean volcanic soils, representing three different successional stages
with ages of 380, 269 and 63 years, respectively. A total of 19
metagenome-assembled genomes (MAGs) were retrieved from all stages with
a higher number observed in the youngest soil (1640: 2 MAGs, 1751: 1
MAG, 1957: 16 MAGs). Genomic similarity indices showed that several MAGs
had amino-acid identity (AAI) values >50% to the phyla Actinobacteria,
Acidobacteria, Gemmatimonadetes, Proteobacteria and Chloroflexi. Three
MAGs from the youngest site (1957) belonged to the class Ktedonobacteria
(Chloroflexi). Complete cellular functions of all the MAGs were
characterised, including carbon fixation, terpenoid backbone
biosynthesis, formate oxidation and CO oxidation. All 19 environmental
genomes contained at least one gene encoding a putative carbon monoxide
dehydrogenase (CODH). Three MAGs had form I coxL operon (encoding the
large subunit CO-dehydrogenase). One of these MAGs (MAG-1957-2.1,
Ktedonobacterales) was highly abundant in the youngest soil.
MAG-1957-2.1 also contained genes encoding a [NiFe]-hydrogenase and hyp
genes encoding accessory enzymes and proteins. Little is known about the
Ktedonobacterales through cultivated isolates, but some species can
utilise H-2 and CO for growth. Our results strongly suggest that the
remote volcanic sites in Chile represent a natural habitat for
Ktedonobacteria and they may use reduced gases for growth.
