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See detailCharacterization of YbjG, a pyrophosphate phosphatase from E. coli involved in the lipid carrier undecaprenyl phosphate metabolism
Delbrassine, François ULg; Auger, Rodolphe; El Ghachi, Meriem ULg et al

Poster (2015, June 08)

•Background Undecaprenyl phosphate (C55-P) is an essential lipid carrier involved in the biosynthesis of cell surface carbohydrate polymers such as the peptidoglycan. C55-P is the result of the ... [more ▼]

•Background Undecaprenyl phosphate (C55-P) is an essential lipid carrier involved in the biosynthesis of cell surface carbohydrate polymers such as the peptidoglycan. C55-P is the result of the dephosphorylation of the undecaprenyl pyrophosphate (C55-PP) by specific phosphatases. In Escherichia coli this dephosphorylation can be performed by four integral membrane proteins, BacA, and three members of the type 2 phosphatidic acid phosphatase family (PAP2), PgpB, YbjG, and LpxT. •Objectives The aim of this project is to characterize YbjG and contributes to the understanding of the physiological role and mechanism of action of this enzyme in the C55-P metabolism. The C55-PP phosphatases could become an interesting target in the search for new molecules with antibacterial activity. •Methods In parallel the stability of YbjG and its activity against C15-PP were assessed in 94 different detergents. Moreover the enzymatic activity of YbjG was studied: substrate specificity, optimum pH and temperature, effect of detergent concentration. •Conclusions For the first time, YbjG has been purified and we show its ability to dephosphorylate C15-PP, DGPP and C55-PP in vitro with respectively decreasing efficiency. No activity has been detected on five other potential substrates (PPi, PA, C5-PP, G6P & PNPP). The phosphatase activity on C15-PP is maximum at pH 6,5 and 25 °C. Moreover Cymal6, LMNG, & ωUDM are good detergent both for the stability and the C15-PP phosphatase activity of YbjG, but approximately half of the 94 tested detergents show C15-PP phosphatase activity on the qualitative enzymatic test. [less ▲]

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

Poster (2013, July)

Detailed reference viewed: 86 (21 ULg)
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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 Woronichinia
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 ▲]

Detailed reference viewed: 40 (5 ULg)