Microbial ecology of Antarctic aquatic systems

Cavicchioli, Ricardo

doi:10.1038/nrmicro3549

Cited by 164 publications

(170 citation statements)

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“…A ntarctica supports a rich diversity of life (1), which, like most ecosystems on Earth, is predicated on microorganisms forming the base of the food web (2)(3)(4). In Antarctic aquatic (e.g., lakes and ice) and lithic (soil and rock) environments, microorganisms dominate, and higher trophic organisms are rare (2)(3)(4).…”

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confidence: 99%

“…In Antarctic aquatic (e.g., lakes and ice) and lithic (soil and rock) environments, microorganisms dominate, and higher trophic organisms are rare (2)(3)(4). In the past decade, "omic"-based studies have generated many discoveries about Antarctic microbial ecology, including identifying previously unknown key taxa, microbial processes, gene exchange events, and virus-host interactions (reviewed in references 2-4).…”

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confidence: 99%

“…The Vestfold Hills are located on the coastal fringe of East Antarctica, covering an area of ϳ411 km 2 , and contain numerous lakes that were isolated from the ocean ϳ3,000 to 7,000 years ago during the isostatic rebound of the continent (4,11). Deep Lake (68°33=36.8S, 78°11=48.7E) sits ϳ50 m below sea level, and the salt has concentrated to the highest level (ϳ10 times marine) for any lake in the Vestfold Hills (4,12,13).…”

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confidence: 99%

“…Deep Lake (68°33=36.8S, 78°11=48.7E) sits ϳ50 m below sea level, and the salt has concentrated to the highest level (ϳ10 times marine) for any lake in the Vestfold Hills (4,12,13). The 36-m-deep, 0.58-km 2 (surface area), monomictic system remains ice-free even during winter, when the air temperature drops to around Ϫ40°C (12,13).…”

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confidence: 99%

“…Viruses play a particularly prominent role in the microbial food web in Antarctica because higher trophic predators (e.g., protists) are uncommon (4,20). As reservoirs of biodiversity providing unique genetic potential and mediating gene transfer, viruses control ecosystem function by lysing their hosts and causing the recycling of nutrients, thereby making a unique contribution to global biogeochemical cycles (21)(22)(23).…”

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confidence: 99%

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Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics

Tschitschko

Williams

Allen

et al. 2016

Appl Environ Microbiol

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Deep Lake in the Vestfold Hills is hypersaline and the coldest system in Antarctica known to support microbial growth (temperatures as low as ؊20°C). It represents a strong experimental model because the lake supports a low-complexity community of haloarchaea, with the three most abundant species totaling ϳ72%. Moreover, the dominant haloarchaea are cultivatable, and their genomes are sequenced. Here we use metaproteomics linked to metagenome data and the genome sequences of the isolates to characterize the main pathways, trophic strategies, and interactions associated with resource utilization. The dominance of the most abundant member, Halohasta litchfieldiae, appears to be predicated on competitive utilization of substrates (e.g., starch, glycerol, and dihydroxyacetone) produced by Dunaliella, the lake's primary producer, while also possessing diverse mechanisms for acquiring nitrogen and phosphorus. The second most abundant member, strain DL31, is proficient in degrading complex proteinaceous matter. Hht. litchfieldiae and DL31 are inferred to release labile substrates that are utilized by Halorubrum lacusprofundi, the third most abundant haloarchaeon in Deep Lake. The study also linked genome variation to specific protein variants or distinct genetic capacities, thereby identifying strain-level variation indicative of specialization. Overall, metaproteomics revealed that rather than functional differences occurring at different lake depths or through size partitioning, the main lake genera possess major trophic distinctions, and phylotypes (e.g., strains of Hht. litchfieldiae) exhibit a more subtle level of specialization. This study highlights the extent to which the lake supports a relatively uniform distribution of taxa that collectively possess the genetic capacity to effectively exploit available nutrients throughout the lake. IMPORTANCELife on Earth has evolved to colonize a broad range of temperatures, but most of the biosphere (ϳ85%) exists at low temperatures (<5°C). By performing unique roles in biogeochemical cycles, environmental microorganisms perform functions that are critical for the rest of life on Earth to survive. Cold environments therefore make a particularly important contribution to maintaining healthy, stable ecosystems. Here we describe the main physiological traits of the dominant microorganisms that inhabit Deep Lake in Antarctica, the coldest aquatic environment known to support life. The hypersaline system enables the growth of halophilic members of the Archaea: haloarchaea. By analyzing proteins of samples collected from the water column, we determined the functions that the haloarchaea were likely to perform. This study showed that the dominant haloarchaea possessed distinct lifestyles yet formed a uniform community throughout the lake that was collectively adept at using available light energy and diverse organic substrates for growth.

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Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics

Tschitschko

Williams

Allen

et al. 2016

Appl Environ Microbiol

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Diversity and community composition of particle‐associated and free‐living bacteria in mesopelagic and bathypelagic Southern Ocean water masses: Evidence of dispersal limitation in the Bransfield Strait

Milici

Vital²,

Tomasch

et al. 2017

Limnology & Oceanography

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The Southern Ocean constitutes about 10% of the global oceans' volume and is characterized by high primary production. Particulate organic matter (POM) is exported from the photic zone to the deep ocean and sustains life of particle associated (PA) and free-living (FL) bacterial communities in the dark realm. Little is known about the composition and diversity of PA and FL bacterial communities below the photic zone and how they differ among various regions of the Southern Ocean. Therefore, we investigated the composition of small (3-8 lm) and large (> 8 lm) PA and FL (0.2-3 lm) bacterial communities between 500 m and 3600 m in the Bransfield Strait, Drake Passage, and the south Atlantic Ocean featuring also Southern Ocean water masses. PA bacterial communities had a higher OTU richness and evenness than FL ones. Taxonomic analysis revealed a different community composition between FL and PA bacteria. A large number of OTUs belonging to diverse phyla (Bacteroidetes, Planctomycetes, Betaproteobacteria, Deltaproteobacteria, and Verrucomicrobia) were significantly enriched on particles; in contrast very few bacterial lineages were FL specialists. Lifestyle (FL vs. PA) and region (Bransfield basin vs. other regions) strongly influenced bacterial communities. Depth explained only marginal fraction of the total variation ( 12%), suggesting that selective processes driven by depth have a smaller effect in the Southern Ocean when compared to life-style (25%) and region (31%). Overall these data indicate a strong influence of isolated water masses such as the basin of the Bransfield Strait on the composition of bacterial communities in the dark ocean.

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Comparing microbial composition and diversity in freshwater lakes between Greenland and the Tibetan Plateau

Xing

Tao

2020

Limnology & Oceanography

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Greenland and the Tibetan Plateau, also known as the third pole, are both cold environments where anthropogenic activities are relatively weak. There are multitudinous lakes in both regions, especially in Greenland, where small water bodies are continuously created as glaciers retreat. It is unclear whether the community structure and community assembly mechanisms of these water bodies are consistent with those of lakes in the Tibetan Plateau that were indirectly influenced by glaciers. In addition, due to different evolution times of the lakes, differences of microbial diversity, especially at the sub‐species level, are feasible but not yet reported. Microbial compositions in lake water and sediment were investigated based on high‐throughput sequencing of 16S rRNA genes. The oligotyping analysis revealed disproportionally distributed bacterial oligotypes in lakes between the two different areas. Moreover, microbial macrodiversity and intra‐operational taxonomic units microdiversity is significantly higher in Greenland lakes which experiencing early lake ontogeny. Microbial community composition and functionality significantly distinguished between the two regions and habitats. Multivariate analysis together with null model tests demonstrated that deterministic processes largely controlled the patterns of community structure in the sediment, while stochastic processes are more important for those in pelagic water in both regions. Microbes may be further subject to N and P co‐limitation in line with the evolution of lake ecosystems. The obtained results could help us understand evolution trajectory of these polar lakes under the future climate change scenario.

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Microbial ecology of Antarctic aquatic systems

Cited by 164 publications

References 130 publications

Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics

Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics

Diversity and community composition of particle‐associated and free‐living bacteria in mesopelagic and bathypelagic Southern Ocean water masses: Evidence of dispersal limitation in the Bransfield Strait

Comparing microbial composition and diversity in freshwater lakes between Greenland and the Tibetan Plateau

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