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See detailSuccessional trajectories of cyanobacterial communities following glacier retreat in Svalbard (High Arctic)
Stelmach Pessi, Igor ULiege; Pushkareva, Ekaterina; Borderie, Fabien ULiege et al

Conference (2016, September 01)

The effects of global warming are pronounced at high northern latitudes, where the warming trend observed for the past decades is almost twice as the global average. Most glaciers in Svalbard (High Arctic ... [more ▼]

The effects of global warming are pronounced at high northern latitudes, where the warming trend observed for the past decades is almost twice as the global average. Most glaciers in Svalbard (High Arctic) have been retreating and thinning since the end of the Little Ice Age in the late 19th century, and retreat rates have increased substantially in the last decades. As a glacier retreats, it systematically exposes new terrestrial habitats for the colonization by pioneering (micro)organisms. Distance from the glacier terminus can be used as a proxy for time since deglaciation, which makes glacier forefields well suited for the study of primary succession. In the present study, we investigated the successional trajectories of cyanobacterial communities along a 100-year deglaciation gradient in the forefield of two Svalbard glaciers (Ebba- and Hørbyebreen). Cyanobacterial abundance was assessed by epifluorescence microscopy and cyanobacterial diversity was investigated by pyrosequencing of partial 16S rRNA gene sequences. Filamentous cyanobacteria were more abundant than unicellular and heterocystous cyanobacteria in both forefields, and an increase in the abundance of cyanobacteria was observed along the deglaciation gradients. Pseudanabaenales was the most OTU-rich order, followed by Chroococcales, Oscillatoriales, Synechococcales, Nostocales and Gloeobacterales. At the genus level, classified phylotypes were assigned to Leptolyngbya, Phormidium, Nostoc, Pseudanabaena, Chroococcidiopsis and Microcoleus. Interestingly, OTU richness increased along the deglaciation gradient in Ebbabreen, but an inverse correlation was observed in Hørbyebreen. Beta diversity estimations indicated contrasting cyanobacterial phylogenetic structures along the temporal gradient, with a clear separation of initial (10-20 years), intermediate (30-50) and advanced (80-100) communities. Time since deglaciation accounted for around 25% of the phylogenetic variability in both forefields, with organic carbon content also explaining a significant proportion of community turnover along the deglaciation gradients. Taxonomic composition was somewhat constant along the deglaciation gradient, but OTUs associated with initial communities were related to sequences predominantely restricted to polar biotopes, while advanced communities included phylotypes related to cosmopolitan taxa. [less ▲]

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See detailThe BCCM/ULC collection to conserve and study the biodiversity of Polar cyanobacteria
Wilmotte, Annick ULiege; Renard, Marine ULiege; Lara, Yannick ULiege et al

Poster (2016, September)

The BCCM/ULC public collection of Cyanobacteria has been funded since 2011 by the Belgian Science Policy Office. BCCM/ULC is currently holding 226 cyanobacterial strains, with 119 being of Antarctic ... [more ▼]

The BCCM/ULC public collection of Cyanobacteria has been funded since 2011 by the Belgian Science Policy Office. BCCM/ULC is currently holding 226 cyanobacterial strains, with 119 being of Antarctic origin (including 3 from the sub-Antarctic). The cyanobacteria constitute the bacterial phylum with the largest morphological diversity and their taxonomy is still a work in progress. In Polar Regions, Cyanobacteria represent key primary producers and are important drivers of the food webs in a wide range of aquatic to terrestrial habitats. For example, they build extensive benthic microbial mats in lakes and soil crusts in terrestrial biotopes. They have adapted to their environment, and may present interesting features to survive freeze/thaw cycles, seasonally contrasted light intensities, high UV radiations, dessication and other stresses. In this poster, we present the results of the 16S rRNA phylogenetic analysis for 76 Antarctic strains. This allows us to illustrate the diversity present in the collection, to detect lineages for which no genome has yet been sequenced, and to pinpoint taxonomic problems that should be addressed in a more comprehensive study. [less ▲]

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See detail) Inviolate areas to protect reference sites for future microbiology research in Antarctica
Wilmotte, Annick ULiege; Willems, Anne; Verleyen, Elie et al

Conference (2016, August 22)

Antarctica is a continent dominated by microbes. A surprisingly large biodiversity of well-adapted microorganisms live permanently in a variety of habitats, ranging from ice-free to permanently frozen ... [more ▼]

Antarctica is a continent dominated by microbes. A surprisingly large biodiversity of well-adapted microorganisms live permanently in a variety of habitats, ranging from ice-free to permanently frozen areas. Recent studies revealed that some microbial groups exhibit biogeographic patterns, include endemic taxa and have survived in refugia since the formation of the continental ice sheet. Microbial habitats are under constant pressure due to anthropogenic activities which may introduce non-indigenous microorganisms, via bodies, clothing, cargo and food. New ‘entry points‘ for microbial contamination are a consequence of the increase and diversification of tourism and research stations. Climatic changes might furthermore increase the probability of the successful establishment of populations of non-native taxa. The impacts of such introductions are still unknown, and might lead to a loss of the native microbial biodiversity, or its modification, which in turn might affect ecosystem functioning. The recent technical progress in molecular methodologies have generated very sensitive high-throughput analyses and have the potential to describe microbial communities with unprecedented detail. However, we may be losing the pristine Antarctic areas that would enable scientists to study the native microbial flora, its functions and properties. The Protocol on Environmental Protection of the Antarctic Treaty foresees the designation of Antarctic Specially Protected Areas (ASPA) to protect “outstanding environmental, scientific, historic, aesthetic, or wilderness values, any combination of those values, or on-going or planned scientific research” (http://www.ats.aq/e/ep_protected.htm). However, the designation of ASPAs has not followed a systematic planning, and often focused on the conservation of large mammals, birds and/or vegetation and other iconic species. Microorganisms have the handicap of generally being invisible without a microscope and relevant expertise, and require molecular methods for species delineation. Terrestrial habitats are protected in 55 out of the 72 existing ASPAs (in total less than 700 km2). Microalgae are protected in 16 ASPAs, cyanobacteria in 7 and snow microalgae in 3. Only 8 ASPAs mention ‘Microbial habitats’, ‘microbial communities’ or ‘soil and lake microflora’. One tool of the Protocol that could be specifically used to protect microbial habitats is the creation of inviolate areas where a special entry permit is required (inside ASPAs, for example), and quarantine equipment should be worn. These zones could be set aside for future research and after a few decades, they would be unique examples of truly pristine habitats, and representative of the native microbial diversity. Examples of this are ASPA 126, Byers Peninsula, and ASPA 172, Lower Taylor Glacier and Blood Falls. Such an option would require discussions and a consensus among scientists of other disciplines than microbiology to select these regions, and develop careful management protocols of the sites and their vicinity. In addition, gaps in our knowledge should be addressed, like the extent of transportation of microorganisms by natural means (winds, birds...), and the probability of subsequent colonization of new areas by microorganisms coming from other Antarctic regions or from outside Antarctica. Let’s hope that the dialogue between scientists and policy makers will improve the conservation of Antarctic microbial diversity and safeguard the possibility to study these unique communities in the future by the next generation of scientists, with the most advanced techniques of the time. [less ▲]

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See detailThe BCCM/ULC collection: a Biological Ressource Center to give access to the Antarctic cyanobacterial diversity
Wilmotte, Annick ULiege; Renard, Marine ULiege; Lara, Yannick ULiege et al

Poster (2016, August)

On the Antarctic continent, Cyanobacteria represent the key primary producers and the main drivers of the food webs in a wide range of aquatic to terrestrial habitats. For example, they build benthic ... [more ▼]

On the Antarctic continent, Cyanobacteria represent the key primary producers and the main drivers of the food webs in a wide range of aquatic to terrestrial habitats. For example, they build benthic microbial mats in lakes and soil crusts in terrestrial biotopes. They may present interesting features to survive freeze/thaw cycles, sea-sonally contrasted light intensities, high UV radiations, dessication and other stresses. The BCCM/ULC public collection funded by the Belgian Science Policy Office since 2011 aims to gather a representative portion of the polar cyanobacterial diversity with different ecological origins (limnetic microbial mats, soil crusts, cryoconites, endoliths, etc.). It makes it available for researchers to study the taxonomy, evolu-tion, adaptations to harsh environmental conditions, and genomic make-up. It pres-ently includes 226 cyanobacterial strains, with 119 being of Antarctic origin (cata-logue: http://bccm.belspo.be/catalogues/ulc-catalogue-search). The morphological identification shows that the strains belong to the orders Synechococcales, Oscillatoriales, Pleurocapsales, Chroococcidiopsidales and Nostocales. We present here the molecular datasets showing the diversity of the BCCM/ULC strains, studied on the basis of the 16S rRNA gene. A selection of strains was also characterized by sequencing of rpoC1, recA, and gyrA genes after amplification with newly designed primers. Our results mainly show that 25 OTUs included strains of Antarctic origin. Moreo-ver, strains identified as members of the genera Leptolyngbya or Phormidium ap-pear in several lineages. This supports the need to revise these polyphyletic genera with a simple filamentous morphology. A certain divergence of some Antarctic strains from related strains isolated from other regions can also be observed. It suggests that a portion of the Antarctic cyanobacterial flora may have evolved in-dependently from the cyanobacteria in other continents. [less ▲]

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See detailMicroalgae diversity along an Antarctic glacier forefield
Stelmach Pessi, Igor ULiege; Rybalka, Natalia; Friedl, Thomas et al

Poster (2016, August)

Glacier retreat due to global warming has been observed in all the cryosphere [1], systematically exposing new terrestrial ecosystems that had previously been covered by ice. Primary succession, i.e. the ... [more ▼]

Glacier retreat due to global warming has been observed in all the cryosphere [1], systematically exposing new terrestrial ecosystems that had previously been covered by ice. Primary succession, i.e. the assembly of biological communities on newly exposed habitats and their change over time, can be studied along glacier forefields, where distance from the glacier terminus is used as a proxy for time since deglaciation [2]. The study of microbial succession is still at its infancy, but understanding the relationships between microbial communities and soil development will provide us with crucial knowledge on how they influence and respond to changes in environmental conditions. Here, we investigated the structure of microalgal communities along a deglaciation gradient in the forefield of Collins Glacier (Fildes Peninsula, King George Island, Maritime Antarctica). [less ▲]

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See detailDiversity and distribution of microorganisms in microbial mats of Antarctic lakes
Lara, Yannick ULiege; Durieu, Benoit ULiege; Stelmach Pessi, Igor ULiege et al

Conference (2016, August)

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopic observations, strain ... [more ▼]

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopic observations, strain isolation and genetic characterisation, and molecular diversity assessments using Next Generation Sequencing of environmental DNA. The samples were collected in different Antarctic and sub-Antarctic biogeographical regions. Preliminary multivariate analysis of >130 samples revealed strong bioregionalisation patterns in microbial eukaryotes, which are in agreement with the classical subdivision of the Antarctic Realm into Maritime Antarctica, Continental Antarctica and the Sub-Antarctic Islands generally observed in plants and animals. The biogeographic structuring was less strong between the continent and Maritime Antarctica in prokaryotes suggesting more regular dispersal events between these two regions. The Sub-Antarctic assemblages harboured more complex foodwebs, with arthropods, nematods, rotifers, flatworms and annelids as main metazoan groups. Lakes on the continent, however, were characterised by fewer metazoan groups and a greater importance of microbial herbivores and secondary consumers, including a relative high diversity of ciliates and tardigrades. In a first analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub-Antarctic, the majority of the cyanobacterial OTUs retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus, Chamaesiphon, Calothrix and Coleodesmium were also found. Results revealed a much higher diversity than what had been reported using traditional methods and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. In the coming months, the molecular diversity data will be deposited into the “Microbial Antarctic Resource System (MARS)” presently developed into the webportal ‘biodiversity.aq’. Better knowledge of the diversity and distribution of microorganisms will contribute to a better assessment of their resilience and local/regional responses to global change [less ▲]

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See detailCyanobacterial diversity in soil crusts in the Sör Rondane Mountains
Namsaraev, Zorigto; Mano, Marie-José; Wilmotte, Annick ULiege

Poster (2016, August)

Antarctica is the only continent that is dominated by microbial (cyanobacteria and algae) and lower plant (predominantly mosses and lichens) communities. Cyanobacteria are photosynthetic bacteria that ... [more ▼]

Antarctica is the only continent that is dominated by microbial (cyanobacteria and algae) and lower plant (predominantly mosses and lichens) communities. Cyanobacteria are photosynthetic bacteria that require solar light, liquid water, air and some mineral nutrients for growth. They serve as primary producers of organic matter in Antarctic ecosystems providing energy to other physiological groups of microorganisms and invertebrates. Cyanobacteria form macroscopically visible crusts or thin biofilms on the surface of soils and rocks, or occupy endolithic niches in Antarctic mountains. Mountains exposed above the ice sheet could have remained ice-free during glaciation maxima in Antarctica. They could serve as a refuge for terrestrial biodiversity and potential source for recolonization of surrounding habitats during glacier retreat. Cyanobacterial diversity in habitats located above 1 km a.s.l. was studied in several Antarctic locations. These include: the Vinson Massif in Ellsworth Mountains (2000-2500 m a.s.l.), Beacon (1176 m a.s.l.) and University Valleys (1700 m a.s.l.) in the "stable upland zone" of the McMurdo Dry Valleys (Southern Victoria Land) and the Sör Rondane Mountains (1370-1700 m a.s.l.) (Yergeau et al., 2007; Wood et al., 2008; Fernandez-Carazo et al., 2012). The goal of our work was to study cyanobacterial diversity of cyanobacteria in the Sör Rondane Mountains in the vicinity of Belgian Princess Elisabeth Station. Previous estimates of the diversity showed the presence of 10 morphotypes and 13 OTUs of cyanobacteria in 10 samples of biofilms and microbial crusts (Fernandez-Carazo et al., 2012). We performed a broader sampling and studied cyanobacterial diversity using DGGE with cyanospecific primers and microscopy. In 126 samples, we observed 15 morphotypes of cyanobacteria. 28 representative samples were selected for molecular analyses that revealed the presence of 28 OTUs (groups of 16S rRNA sequences sharing at least 97,5% sequence similarity). Comparison with other mountainous areas of Antarctica showed that the Sör Rondane Mountains harbor a significantly higher cyanobacterial diversity. Molecular analysis of the cyanobacterial diversity in Beacon Valley didn't show the presence of cyanobacteria (Wood et al., 2008), though a strain of Chroococcidiopsis sp. (CCMEE 134) was isolated from a sample collected there (Billi et al., 2011). A strain of Chroococcidiopsis sp. (CCMEE 171-A789-2) was also isolated from samples collected in University Valley (Cumbers & Rothschild, 2014). 5 OTUs of cyanobacteria were detected in samples collected in Ellsworth Mountains despite of the presumably harsher climate (78°31′S latitude compared to 77°49′S for Beacon Valley) and higher altitude (Yergeau et al., 2007). No reliable climate data are available for the discussed areas, except for the Sor Rondane Mountains. We propose that the higher diversity of cyanobacteria detected near the Princess Elisabeth Station could be explained by a more intensive sampling or by a more northern location of the area (72°0′S). [less ▲]

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See detailCharacterization of Leptolyngbya and Phormidium diversity in Antarctic biotopes
Lara, Yannick ULiege; Durieu, Benoit ULiege; Borderie, Fabien et al

Poster (2016, August)

Detailed reference viewed: 34 (9 ULiège)
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See detailNarrowing the science/policy gap for environmental management
Hughes, Kevin A; Liggett, Daniela; Roldan, Gabriela et al

in Antarctic Science (2016), 28(5), 325

Antarctic terrestrial and marine environments are under increasing pressure from national operator activities, tourism and climate change. The Protocol on Environmental Protection to the Antarctic Treaty ... [more ▼]

Antarctic terrestrial and marine environments are under increasing pressure from national operator activities, tourism and climate change. The Protocol on Environmental Protection to the Antarctic Treaty provides overarching legislation concerning the environmental management of the Treaty area, with 2016 marking the Protocol’s 25th anniversary. The Protocol also established the Committee for Environmental Protection (CEP) to provide advice to the Antarctic Treaty Consultative Meeting (ATCM) on environmental matters. Today, the CEP’s Five-Year Work Plan and Climate Change Response Work Programme lists and prioritises issues that need to be addressed to ensure impacts in Antarctica by human activities are both recognized andminimised.Despite all of this, recent evaluations have suggested that a slow pace of environmental policy development presents a significant threat to effective Antarctic conservation. Progress on many environmental issues, including wildlife disturbance, the conservation status of Antarctic species, area protection and pollution management, is glacial or has stalled completely. Whilst in some cases capacity issues concerning those responsible for Antarctic environmental policy work may be a contributing factor, the level of interaction between researchers and those responsible for environmental management and decision-making is also of importance. Without quality science - and effective interpretation of research results - policymakers have little evidence on which to base their decisions. But researchers need to know policymakers’ needs. Two-way communication is essential: policymakers could ask the research community to answer specific environmental questions, and, in turn, researchers could present evidence-based recommendations and highlight emerging threats. But how is this to be funded? Ultimately, effective communication is needed between national government departments responsible for funding Antarctic research and those dealing with Antarctic environmental protection. Hopefully, this will ensure essential research informing environmental policy decisions is adequately resourced. In reality, the cost is likely to be trivial compared with the resources spent by Parties on Antarctic logistics. [less ▲]

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See detailCryopreservation of cyanobacteria in the BCCM/ULC collection: experimental set-up of protocols
Crahay, Charlotte ULiege; Renard, Marine ULiege; Day, John G et al

Conference (2016, June 21)

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See detailDevelopment of improved preservation techniques for cyanobacterial and diatom strains in the BCCM collections
Crahay, Charlotte ULiege; Chepurnova, Olga; Day, John G et al

Poster (2016, June)

Detailed reference viewed: 27 (3 ULiège)
See detailThe CCAMBIO project to characterize the biodiversity and distribution of microorganisms in microbial mats of Antarctic lakes
Durieu, Benoit ULiege; Lara, Yannick ULiege; Obbels, Dagmar et al

Poster (2016, April 29)

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopical observations (light and ... [more ▼]

The BelSPO project CCAMBIO aims to study the biogeographical distribution of microorganisms in lacustrine microbial mats using a combination of techniques including microscopical observations (light and electronic microscopy), strain isolation, and molecular diversity assessment using Next Generation Sequencing. The samples were collected in different Antarctic and sub-Antarctic biogeographical regions. A detailed microscopic study of the Antarctic diatom diversity allowed to revise a number of taxa and discover new ones. A multivariate analysis of diatoms showed that these regions hosted different diatom flora. Endemic diatom taxa were also observed, and a multigene molecular phylogeny of Pinnularia borealis showed a high genetic diversity. Pilot studies were conducted for the microeukaryotes and cyanobacteria to select NGS protocols and bioinformatic pipelines. Preliminary multivariate analysis of over 100 samples revealed that distinct biogeographic zones could be recognized in both the prokaryote and eukaryote data, which is in agreement with the classical subdivision of the Antarctic Realm into Maritime Antarctica, Continental Antarctica and the Sub-Antarctic Islands generally observed in plants and animals. Moreover, Sub-Antarctic assemblages harboured more complex foodwebs, with quite diverse metazoan groups. Lakes on the continent, however, were characterised by fewer metazoan groups and a greater importance of microbial herbivores and secondary consumers, including a relative high diversity of ciliates and tardigrades. Variation partitioning analysis revealed that spatial variables that approximated large-scale regional contrasts in historical (e.g. deglaciation history, geological origin) and climatic factors (e.g. mean annual air temperature) significantly explained the largest portion of the observed variation in community structure for eukaryotes, while in the prokaryote data environmental gradients related to conductivity were more important. In a first analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub-Antarctic, the majority of the cyanobacterial OTUs retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus, Chamaesiphon, Calothrix and Coleodesmium were also found. Results revealed a higher diversity than what had been reported using traditional methods based on microscopic observations and cultivation and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. In the next months, the molecular diversity data will be deposited into the “Microbial Antarctic Resource System (MARS)” presently developed into the webportal ‘biodiversity.aq’. The better knowledge of the diversity and distribution of microorganisms will contribute to a better assessment of their resilience and local/regional responses to global change. [less ▲]

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See detailElucidating diversity of thin filamentous mat-forming Antarctic cyanobacteria
Lara, Yannick ULiege; Durieu, Benoit ULiege; Deblander, Victor ULiege et al

Poster (2016, April 29)

Freshwater ecosystems range from glacial cryoecosystems, ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In ... [more ▼]

Freshwater ecosystems range from glacial cryoecosystems, ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In these mats, cyanobacteria form matrices that shelter other organisms, and carry out the primary production. Narrow filamentous cyanobacteria belonging to the genera Leptolyngbya and Phormidium are especially abundant in Antarctic microbial mats and are essential for the formation of matrix. However, the lack of morphological criteria and the small cell size of cyanobacteria belonging to these two genera make their identification problematic. Indeed, they are known as polyphyletic taxa according to botanical and bacteriological criteria. The characterization of strains is the first step for an assessment of the real diversity and for understanding their role in the environment. We designed a polyphasic approach that combines molecular analyses, environmental physiology experiments and microscopic observations. Briefly, we amplified and sequenced three loci (16S rRNA, ITS, and rpoC1) for 31 strains of Leptolyngbya and Phormidium. We performed whole genome sequencing for five strains. Cultures at different stage were observed by light and epifluorescence microscopy. Finally, selected strains were grown in nitrogen-limited. The Leptolyngbya and Phormidium strains were distributed into four lineages. Phylogenetic trees supported the distribution of P. priestleyi strains into at least two potentially new lineages, and L. antarctica strains were separated into one endemic and one cosmopolitan lineage. This was supported by the microscopic observations of 1-year old cultures. Genome analyses revealed the presence of sequences related to the production of secondary metabolites in strains from two of the studied lineages. Secondary metabolites are often known for their antimicrobial activities. Such properties would partly explain how cyanobacterial mats survive to predation and degradation by other bacteria. This work provides the first building block to the understanding of survival strategies developed by mat-forming cyanobacteria and how they succeeded as the most abundant phototrophs on the Antarctic continent. This work was realized in the frame of the BelSPo project CCAMBIO. [less ▲]

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See detailGram-Negative Bacteria: "Inner" vs. "Cytoplasmic" or "Plasma Membrane": A Question of Clarity rather than Vocabulary
Baurain, Denis ULiege; Wilmotte, Annick ULiege; Frère, Jean-Marie ULiege

in Journal of Microbial and Biochemical Technology (2016), 8(4), 325-326

In this short commentary, we show that the utilisation of the term “inner membrane” to characterize the cytoplasmic or plasma membrane of Gram-negative bacteria can be a source of confusion and we propose ... [more ▼]

In this short commentary, we show that the utilisation of the term “inner membrane” to characterize the cytoplasmic or plasma membrane of Gram-negative bacteria can be a source of confusion and we propose that it should be completely abandoned. [less ▲]

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See detailBacterial community composition in relation to bedrock type and macrobiota in soils 1 from the Sør Rondane Mountains, East Antarctica
Tytgat, Bjorn; Verleyen, Elie; Sweetlove, Maxime et al

in FEMS Microbiology Ecology (2016), 92

Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expected that this is particularly the case for inland high altitude regions. We hypothesized that the bedrock ... [more ▼]

Antarctic soils are known to be oligotrophic and of having low buffering capacities. It is expected that this is particularly the case for inland high altitude regions. We hypothesized that the bedrock type and the presence of macrobiota in these soils enforce a high selective pressure on their bacterial communities. To test this, we analysed the bacterial community structure in 52 soil samples from the western Sør Rondane Mountains (Dronning Maud Land, East Antarctica) using the Illumina MiSeq platform in combination with ARISA fingerprinting. The samples were taken along broad environmental gradients in an area covering nearly 1000 km². Ordination and variation partitioning analyses revealed that the total organic carbon content was the most significant variable in structuring the bacterial communities, followed by pH, electric conductivity, bedrock type and the moisture content, while spatial distance was of relatively minor importance. Acidobacteria (Chloracidobacteria) and Actinobacteria (Actinomycetales) dominated gneiss derived mineral soil samples, while Proteobacteria (Sphingomonadaceae), Cyanobacteria, Armatimonadetes and candidate division FBP dominated soil samples with a high total organic carbon content that were mainly situated on granite derived bedrock. [less ▲]

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See detailBacterial and eukaryotic biodiversity patterns in terrestrial and aquatic habitats in the 1 Sør Rondane Mountains, Dronning Maud Land, East Antarctica
Obbels, Dagmar; Verleyen, Elie; Mano, Marie-José et al

in FEMS Microbiology Ecology (2016), 92

The bacterial and microeukaryotic biodiversity were studied using pyrosequencing analysis on a 454 GS FLX+ platform of partial SSU rRNA genes in terrestrial and aquatic habitats of the Sør Rondane ... [more ▼]

The bacterial and microeukaryotic biodiversity were studied using pyrosequencing analysis on a 454 GS FLX+ platform of partial SSU rRNA genes in terrestrial and aquatic habitats of the Sør Rondane Mountains, including soils, on mosses, endolithic communities, cryoconite holes and supraglacial and subglacial meltwater lenses. This inventory was complemented with Denaturing Gradient Gel Electrophoresis targeting Chlorophyta and Cyanobacteria. OTUs belonging to the Rotifera, Chlorophyta, Tardigrada, Ciliophora, Cercozoa, Fungi, Bryophyta, Bacillariophyta, Collembola and Nematodawere present with a relative abundance of at least 0.1% in the eukaryotic communities. Cyanobacteria, Proteobacteria, Bacteroidetes, Acidobacteria, FBP and Actinobacteria were the most abundant bacterial phyla. Multivariate analyses of the pyrosequencing data revealed a general lack of differentiation of both eukaryotes and prokaryotes according to habitat type. However, the bacterial community structure in the aquatic habitats was dominated by the filamentous cyanobacteria Leptolyngbya and appeared to be significantly different compared with those in dry soils, on mosses, and in endolithic habitats. A striking feature in all datasets was the detection of a relatively large amount of sequences new to science, which underscores the need for additional biodiversity assessments in Antarctic inland locations. [less ▲]

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See detailPolyphasic characterization of 10 selected ecologically relevant filamentous cyanobacterial strains from the South Shetland Islands, Maritime Antarctica
Jancusova, Miroslava; Kovacik, Lubomir; Pereira, Antonio Batista et al

in FEMS Microbiology Ecology (2016), 92(7), 100

The evolutionary relationships of 10 Antarctic cyanobacterial strains of the order Oscillatoriales isolated from King George and Deception Islands, South Shetland Islands were studied by a polyphasic ... [more ▼]

The evolutionary relationships of 10 Antarctic cyanobacterial strains of the order Oscillatoriales isolated from King George and Deception Islands, South Shetland Islands were studied by a polyphasic approach (morphology, 16S rRNA and internal transcribed spacer sequences). The studied taxa are characteristic of coastal Antarctic biotopes, where they form distinct populations and ecologically delimited communities. They were isolated from terrestrial habitats: microbial mats in seepages; crusts on soil, rocks, bones and mosses; mud, sometimes close to bird colonies; and from guano. Based on major phenotypic features, the strains were divided into four distinct morphotypes: Leptolyngbya borchgrevinkii (A), Leptolyngbya frigida (B), Microcoleus sp. (C) and Wilmottia murrayi (D). This morphological identification was in agreement with the phylogenetic relationships. For the first time, the 16S rRNA gene sequence of a strain corresponding to the L. borchgrevinkii morphotype was determined. Morphotype B is most related to sequences assigned to L. frigida isolated from microbial mats of coastal lakes in East Antarctica. Morphotype C belongs to a cluster including strains with morphotypes corresponding to Microcoleus attenuatus, Microcoleus favosus and Microcoleus sp., which are from Antarctica and other continents. Morphotype D is grouped with sequences assigned to W. murrayi mostly isolated from Antarctica. [less ▲]

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See detailON THE USE OF HIGH-THROUGHPUT SEQUENCING FOR THE STUDY OF CYANOBACTERIAL DIVERSITY IN ANTARCTIC AQUATIC MATS 1
Stelmach Pessi, Igor ULiege; De Carvalho Maalouf, Pedro; Laughinghouse, Haywood Dail et al

in Journal of Phycology (2016), 52

The study of Antarctic cyanobacterial diversity has been mostly limited to morphological identification and traditional molecular techniques. High-throughput sequencing (HTS) allows a much better ... [more ▼]

The study of Antarctic cyanobacterial diversity has been mostly limited to morphological identification and traditional molecular techniques. High-throughput sequencing (HTS) allows a much better understanding of microbial distribution in the environment, but its application is hampered by several methodological and analytical challenges. In this work we explored the use of HTS as a tool for the study of cyanobacterial diversity in Antarctic aquatic mats. Our results highlight the importance of using artificial communities to validate the parameters of the bioinformatics procedure used to analyse natural communities, since pipeline-dependent biases had a strong effect on the observed community structures. Analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub-Antarctic showed that HTS is a valuable tool for the assessment of cyanobacterial diversity. The majority of the OTUs retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus and Chamaesiphon, Calothrix and Coleodesmium were also found. Results revealed a much higher diversity than what had been reported using traditional methods and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. The aquatic biofilm from the Sub-Antarctic had a distinct cyanobacterial community in comparison to the studied Antarctic lakes, which, in turn, displayed a salinity-dependent community-structure at the phylotype level. [less ▲]

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See detailIdentifying the factors determining blooms of cyanobacteria in a set of shallow lakes
Descy, Jean-Pierre; Leprieur, Fabien; Pirlot, Samuel et al

in Ecological Informatics (2016), 34

There is a strong interest in developing a capacity to predict the occurrence of cyanobacteria blooms in lakes and to identify the measures to be taken to reduce water quality problems associated with the ... [more ▼]

There is a strong interest in developing a capacity to predict the occurrence of cyanobacteria blooms in lakes and to identify the measures to be taken to reduce water quality problems associated with the occurrence of potentially harmful taxa. Here we conducted a weekly to bi-weekly monitoring program on five shallow eutrophic lakes during two years, with the aim of gathering data on total cyanobacterial abundance, as estimated from marker pigments determined by HPLC analysis of phytoplankton extracts. We also determined bloom composition and measured weather and limnological variables. The most frequently identified taxa were Aphanizomenon flos-aquae, Microcystis aeruginosa, Planktothrix agardhii and Anabaena spp. We used the data base composed of a total of 306 observations and an adaptive regression trees method, the boosted regression tree (BRT), to develop predictive models of bloom occurrence and composition, based on environmental conditions. Data processing with BRT enabled the design of satisfactory prediction models of cyanobacterial abundance and of the occurrence of the main taxa. Phosphorus (total and soluble reactive phosphate), dissolved inorganic nitrogen, epilimnion temperature, photoperiod and euphotic depth were among the best predictive variables, contributing for at least 10 % in the models, and their relative contribution varied in accordance with the ecological traits of the taxa considered. Meteorological factors (wind, rainfall, surface irradiance) had a significant role in species selection. Such results may contribute to designing measures for bloom management in shallow lakes. [less ▲]

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See detailAerobiology over Antarctica – a new initiative for atmospheric ecology
Pearce, David; Alekhina, Irina; Terauds et al

in Frontiers in Microbiology (2016), 7

The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has ... [more ▼]

The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has been long known that the rate of dispersal to an ecosystem can significantly influence ecosystem dynamics, and that aerial transport has been identified as an important source of biological input to remote locations. With the considerable effort devoted in recent decades to understanding atmospheric circulation in the south-polar region, a unique opportunity has emerged to investigate the atmospheric ecology of Antarctica, from regional to continental scales. This concept note identifies key questions in Antarctic microbial biogeography and the need for standardized sampling and analysis protocols to address such questions. A consortium of polar aerobiologists is established to bring together researchers with a common interest in the airborne dispersion of microbes and other propagules in the Antarctic, with opportunities for comparative studies in the Arctic. [less ▲]

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