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See detailBioregionalisation and biodiversity of Cyanobacterial communities in East- Antarctic lakes
De Carvalho Maalouf, Pedro ULg; Stelmach Pessi, Igor ULg; Verleyen, Elie et al

Poster (2013, July)

On the Antarctic continent, ice-free regions represent only 0.3% of the total surface area. In these regions, cyanobacteria are one of the dominant phototrophs and primary producers, forming cohesive ... [more ▼]

On the Antarctic continent, ice-free regions represent only 0.3% of the total surface area. In these regions, cyanobacteria are one of the dominant phototrophs and primary producers, forming cohesive benthic mats in lakes and other aquatic habitats. Using a recent compilation of published biodiversity data from Antarctica and the sub-Antarctic islands in combination with physical factors and expert-defined bioregions, Terauds et al. (2012) identified 15 biologically distinct ice-free Antarctic Conservation Biogeographic Regions (ACBRs). However, the degree and nature of bioregionalisation in Antarctic cyanobacterial communities is still largely unknown. In this study, cyanobacterial diversity was analysed using Denaturating Gradient Gel Electrophoresis (DGGE) on a partial 16S rRNA sequence (ca 400 bp) in 50 microbial mats originating from five of the seven ACBRs identified in East Antarctica. Comparison of the sequences with those available in GenBank was carried out to assess the geographical distribution of the taxa on both local and global scales. A total of 35 Operational Taxonomic Units (OTUs, group of sequences with more than 98.5% sequence similarity) was obtained for all samples. Moreover, the taxonomic turnover between the five ACBRs was relatively low, as 69.5% of the OTUs were present in 2 or 3 bioregions. Consistent with previous findings, a large proportion (37%) of the OTUs was restricted to the “cold biosphere”, and 17% appeared potentially endemic to the Antarctic continent. These results suggest that the patterns of bioregionalisation in East Antarctic cyanobacteria are different than the ACBR scheme. Therefore, it would be useful to study the microbial bioregionalisation in more detail and using less conserved molecular taxonomic markers than the 16S rRNA gene, such as the ITS region. Moreover, since DGGE only provides information on the dominant taxa in microbial assemblages, a high-throughput screening is currently being performed. [less ▲]

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See detailA cultivation-independent approach for the genetic and cyanotoxin characterization of colonial cyanobacteria
Lara, Yannick ULg; Lambion, Alexandre ULg; Menzel, Diana et al

in Aquatic Microbial Ecology (2013), 69

To bypass the constraint of cyanobacterial strain isolation and cultivation, a combination of whole genome amplification (WGA) and enzyme-linked immunoassay (ELISA) for microcystin toxins (MCs) was tested ... [more ▼]

To bypass the constraint of cyanobacterial strain isolation and cultivation, a combination of whole genome amplification (WGA) and enzyme-linked immunoassay (ELISA) for microcystin toxins (MCs) was tested on individual colonies of Microcystis and Woronichinia, taken directly from aquatic environments. Genomic DNA of boiled cells was amplified by multiple strand displacement amplification (MDA), followed by several specific PCR reactions to characterize the genotype of each colony. Sequences of 3 different housekeeping genes (ftsZ, gltX, and recA), of 3 MC biosynthesis genes (mcyA, mcyB, and mcyE), and the Internal Transcribed Spacer (ITS) were analyzed for 11 colonies of Microcystis. MCs were detected and quantified by ELISA in 7 of the 11 Microcystis colonies tested, in agreement with the detection of mcy genes. Sequence types (ST) based on the concatenated sequences of housekeeping genes from cyanobacterial colonies from Belgian water bodies appeared to be endemic when compared to those of strains described in the literature. One colony appeared to belong to a yet undiscovered lineage. A similar protocol was used for 6 colonies of the genus Woronichinia, a taxon that is very difficult to cultivate in the laboratory. The 16S rRNA sequences of 2 colonies were obtained and were quasi identical to that of W. naegeliana 0LE35S01. For one Woronichinia colony, the mcyE PCR gave a non-specific PCR product. The corresponding amino acid sequence was 50% identical to a Microcystis ketoacyl carrier protein transferase. This approach for the simultaneous detection and quantification of MCs with mcy genotyping, at single colony level, offers potential for the ecotoxicological characterization of environmental populations of cyanobacteria without the need for strain isolation and culture. [less ▲]

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See detailAntarctic cyanobacterial diversity: how important are the geographical and ecological factors?
De Carvalho Maalouf, Pedro ULg; Lambion, Alexandre ULg; Gillard, Benjamin et al

Conference (2012, October 31)

On the Antarctic continent, cyanobacteria produce conspicuous benthic microbial mats in lakes, from the coastal regions to the mountains (till 84°S). However, little is known about theirl biodiversity in ... [more ▼]

On the Antarctic continent, cyanobacteria produce conspicuous benthic microbial mats in lakes, from the coastal regions to the mountains (till 84°S). However, little is known about theirl biodiversity in comparison with other regions of the world. The BelSPO project AMBIO aimed to test whether (i) microbial communities are structured by the same factors as those shaping communities of macroorganisms, and (ii) endemism among cyanobacteria does exist. We have analyzed the cyanobacterial biodiversity in a variety of aquatic habitats from the three main biogeographical regions (Continental, Maritime Antarctica and the Sub-Antarctic) and determined the ‘baseline’ data needed to understand the contribution of various processes that are responsible for the distribution patterns. [less ▲]

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See detailAntarctic cyanobacterial diversity: how important are the geographical and ecological factors?
De Carvalho Maalouf, Pedro ULg; Lambion, Alexandre ULg; Gillard, Benjamin et al

Conference (2011, February)

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See detailPotentiel secondary metabolite biosynthesis operons in environmental colonies of Woronischinia
Lara, Yannick ULg; Lambion, Alexandre ULg; Codd, Goeffrey A. et al

Poster (2010, September 01)

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See detailCyanobacterial 
molecular 
diversity 
and distribution 
in 
microbial 
mats from 
antarctic 
lakes
De Carvalho Maalouf, Pedro ULg; Lambion, Alexandre ULg; Zakhia, Frédéric et al

Poster (2009, December 11)

The coastal deglaciated areas of Antarctica hold lakes and other water bodies with a wide spectrum of limnological conditions. Aquatic habitats offer milder conditions to the microorganisms, which are the ... [more ▼]

The coastal deglaciated areas of Antarctica hold lakes and other water bodies with a wide spectrum of limnological conditions. Aquatic habitats offer milder conditions to the microorganisms, which are the only permanent inhabitants of this glacial desert. Among them, cyanobacteria are the first photosynthetic colonisers, sometimes forming thick, cohesive and pigmented benthic mats. In the frame of the BELSPO AMBIO project (Antarctic Microbial BIOdiversity, influence of geographical and ecological factors, www.ambio.ulg.ac.be), we have obtained benthic mat samples coming from lakes from various coastal regions of the continent (MERLIN 2007 and BELARE 2007 field campaigns and by collaborations). We have investigated cyanobacterial molecular diversity via Polymerase Chain Reaction and Denaturating Gradient Gel Electrophoresis (PCR-DGGE) on a set of 80 samples. We couple the numerical analysis of the obtained band patterns with the phylogenetic analysis of the sequences, and by using multivariate analysis, we will assess the role of the ecological and geographical factors shaping the distribution and the diversity of cyanobacteria. Preliminary results of the analysis of 13 samples seem to indicate that lakes separated by a small distance have different cyanobacterial communities, highlighting the importance of ecological factors. Fifty per cent of the obtained Operational Taxonomic Units (OTUs) are potentially endemic to Antarctica while others seem to have a global distribution. The completed study will give us a wide scale view on the distribution and the diversity of cyanobacteria in two biogeographical zones: Continental Antarctica and Maritime Antarctica. Finally, our studies will supply new data and arguments for the ongoing “everything is everywhere, but the environment selects” debate concerning microbial biogeography. [less ▲]

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See detailDiversité moléculaire des cyanobactéries planctonniques dans les eaux de surface belges
Lara, Yannick ULg; Lambion, Alexandre ULg; Simon, Patricia ULg et al

Poster (2008, April 02)

Les développements massifs de cyanobactéries ou ‘blooms’ sont devenus un phénomène récurrent et de plus en plus important dans les eaux douces du monde entier durant la dernière décennie. Ces ... [more ▼]

Les développements massifs de cyanobactéries ou ‘blooms’ sont devenus un phénomène récurrent et de plus en plus important dans les eaux douces du monde entier durant la dernière décennie. Ces efflorescences présentent des risques potentiels majeurs pour la santé humaine et animale et interfèrent négativement avec l'utilisation des eaux de surface par exemple, pour le captage d'eau potable, les loisirs nautiques, l'irrigation, les exploitations piscicoles. Entre 25 et 70% des blooms sont toxiques. Comme beaucoup de pays la Belgique n'a pas échappé au problème des efflorescences de cyanobactéries toxiques, mais il y a encore relativement peu de données. Durant la dernière décennie, trois projets européens et nationaux (MIDICHIP 1999-2003, B-BLOOMS 2003-2005, B-BLOOMS 2 2007-2011) se sont intéressés à la diversité des cyanobactéries dans les eaux de surfaces belges. Nous présentons ici un arbre phylogénétique élaboré à partir d’ un pool de 249 séquences partielles du gène codant pour l’ARNr 16S obtenu à partir de 31 échantillons d’eaux belges issus de ces projets. Cet arbre représente la mise à jour d’une base de données qui constitue l’inventaire des cyanobactéries d’eaux douces belges. Cette base de données permet le suivi de l’évolution de la diversité observable de ces organismes en Belgique et la surveillance de l’apparition d’espèces tropicales comme conséquence aux changements climatiques globaux. [less ▲]

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