Abstract:Arsenic metabolism is proposed to be an ancient mechanism in microbial life. Different bacteria and archaea use detoxification processes to grow under high arsenic concentration. Some of them are also able to use arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. However, among the archaea, bioenergetic arsenic metabolism has only been found in the Crenarchaeota phylum. Here we report the discovery of haloarchaea (Euryarchaeota phylum) biofilms… Show more
“…The number and diversity of the identified proteins suggest that many microorganisms in this environment are capable of using arsenic as an energy source. This mechanism could be widespread in high altitude Andean arsenic systems, as shown in findings at Diamante Lake 8 .Figure 6ArrA subfamily maximum likelihood tree. The arsenite oxidases clade ArxA is shown in light grey and the arsenate reductases in dark grey.…”
Section: Resultsmentioning
confidence: 83%
“…These enzymes are frequently present in environments where arsenic is rife. In Archaea, they were reported for the first time at Diamante –another HAAL located in the caldera of Galán Volcano– with an As content in water of 119 mg L −1
8 . The respiratory oxidases and reductases are large proteins, with usually at least 800 residues, so only a limited number was available for phylogenetic trees, as complete genes could only be found in the larger contigs.…”
Section: Resultsmentioning
confidence: 99%
“…Diamante Lake (Argentina) 8 , another HAAL location recently described with even more extreme conditions, was also included in the comparison. By both a taxonomical and a functional analysis on a broad level, Socompa’s metagenome was similar to Shark Bay smooth mats (Fig.…”
Modern stromatolites thrive only in selected locations in the world. Socompa Lake, located in the Andean plateau at 3570 masl, is one of the numerous extreme Andean microbial ecosystems described over recent years. Extreme environmental conditions include hypersalinity, high UV incidence, and high arsenic content, among others. After Socompa’s stromatolite microbial communities were analysed by metagenomic DNA sequencing, taxonomic classification showed dominance of Proteobacteria, Bacteroidetes and Firmicutes, and a remarkably high number of unclassified sequences. A functional analysis indicated that carbon fixation might occur not only by the Calvin-Benson cycle, but also through alternative pathways such as the reverse TCA cycle, and the reductive acetyl-CoA pathway. Deltaproteobacteria were involved both in sulfate reduction and nitrogen fixation. Significant differences were found when comparing the Socompa stromatolite metagenome to the Shark Bay (Australia) smooth mat metagenome: namely, those involving stress related processes, particularly, arsenic resistance. An in-depth analysis revealed a surprisingly diverse metabolism comprising all known types of As resistance and energy generating pathways. While the ars operon was the main mechanism, an important abundance of arsM genes was observed in selected phyla. The data resulting from this work will prove a cornerstone for further studies on this rare microbial community.
“…The number and diversity of the identified proteins suggest that many microorganisms in this environment are capable of using arsenic as an energy source. This mechanism could be widespread in high altitude Andean arsenic systems, as shown in findings at Diamante Lake 8 .Figure 6ArrA subfamily maximum likelihood tree. The arsenite oxidases clade ArxA is shown in light grey and the arsenate reductases in dark grey.…”
Section: Resultsmentioning
confidence: 83%
“…These enzymes are frequently present in environments where arsenic is rife. In Archaea, they were reported for the first time at Diamante –another HAAL located in the caldera of Galán Volcano– with an As content in water of 119 mg L −1
8 . The respiratory oxidases and reductases are large proteins, with usually at least 800 residues, so only a limited number was available for phylogenetic trees, as complete genes could only be found in the larger contigs.…”
Section: Resultsmentioning
confidence: 99%
“…Diamante Lake (Argentina) 8 , another HAAL location recently described with even more extreme conditions, was also included in the comparison. By both a taxonomical and a functional analysis on a broad level, Socompa’s metagenome was similar to Shark Bay smooth mats (Fig.…”
Modern stromatolites thrive only in selected locations in the world. Socompa Lake, located in the Andean plateau at 3570 masl, is one of the numerous extreme Andean microbial ecosystems described over recent years. Extreme environmental conditions include hypersalinity, high UV incidence, and high arsenic content, among others. After Socompa’s stromatolite microbial communities were analysed by metagenomic DNA sequencing, taxonomic classification showed dominance of Proteobacteria, Bacteroidetes and Firmicutes, and a remarkably high number of unclassified sequences. A functional analysis indicated that carbon fixation might occur not only by the Calvin-Benson cycle, but also through alternative pathways such as the reverse TCA cycle, and the reductive acetyl-CoA pathway. Deltaproteobacteria were involved both in sulfate reduction and nitrogen fixation. Significant differences were found when comparing the Socompa stromatolite metagenome to the Shark Bay (Australia) smooth mat metagenome: namely, those involving stress related processes, particularly, arsenic resistance. An in-depth analysis revealed a surprisingly diverse metabolism comprising all known types of As resistance and energy generating pathways. While the ars operon was the main mechanism, an important abundance of arsM genes was observed in selected phyla. The data resulting from this work will prove a cornerstone for further studies on this rare microbial community.
“…It is not unreasonable to expect that they may be present on Mars or other planetary bodies, and current thought is that arsenic may have been important to early life on Earth. It is well known that arsenic and selenium are respired by a number of terrestrial microorganisms to conserve energy (Stolz and Oremland, 1999;Zhu et al, 2014;Nancharaiah and Lens, 2015;Rascovan et al, 2016). Interestingly, this study identified 10 microorganisms that grew in media where arsenic was the only terminal electron acceptor available.…”
Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface. Approximately 66% (237) of the 358 microorganisms identified are related to members of the Bacillus genus, although surprisingly, 22% of all isolates belong to non-spore-forming genera. A small number could grow by reduction of potential growth substrates found on Mars, such as perchlorate and sulfate, and many were resistant to desiccation and ultraviolet radiation (UVC). While most isolates either grew in media containing ‡10% NaCl or at 4°C, many grew when multiple physiological stresses were applied. The study yields details about the microorganisms that inhabit the surfaces of spacecraft after microbial reduction measures, information that will help gauge whether microorganisms from Earth pose a forward contamination risk that could impact future planetary protection policy.
“…Together with the recent demonstration of the ability of haloarchaea to oxidize CO (King, 2015), to participate in dissimilatory arsenic cycling (Rascovan et al, 2016) and to actively mineralize insoluble polymers such as chitin and cellulose (Sorokin et al, 2015), it significantly shifts our perception of haloarchaea as an important biogeochemical actor in hypersaline habitats.…”
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