Slovaquie | EPFL Graph Search

La Slovaquie, en forme longue la République slovaque (Slovensko et Slovenská republika), est un pays situé en Europe centrale, au cœur de l'Europe continentale. Elle est membre de l'Union européenne depuis 2004. Ses pays frontaliers sont la Pologne au nord, l'Ukraine à l'est, la Hongrie au sud, l'Autriche à l'ouest et la Tchéquie à l'ouest-nord-ouest. Cœur de la Grande-Moravie, la Slovaquie fit partie du royaume de Hongrie à partir du . Du au , puis du au , elle a, avec la Tchéquie, fait partie de la Tchécoslovaquie. De 1939 à 1945 fut constituée, à partir des décombres de la Tchécoslovaquie, une République slovaque (à moitié démembrée par la Hongrie) au Troisième Reich. La Slovaquie est membre de nombreuses organisations internationales, telles que l'ONU, l'OTAN, l'OMC, l'OCDE ou encore le V4, et fait partie de la zone euro. Toponymie Les noms de la Slovénie, de

WHO IS INTERESTED IN THE REDUCTIVE DECHLORINATION OF POLYCHLORINATED BIPHENYLS (PCBs)?

Christof Holliger, Martina Praveckova, Pierre Rossi

PCBs are persistent organic pollutants which have entered the environment through both use and disposal. The environmental dissemination of PCBs is complex and nearly global in scale, although their production was banned in the 80’s. Nowadays, specific bacterial species were shown to degrade these compounds by attacking the bond between the aromatic core and the flanking chlorine atoms. This anaerobic dechlorination process could be a possible way for environmental bioremediation. Nevertheless, at present time, little is known about the diversity of the bacterial guild and enzymes involved in the process. In this context, anaerobic microcosms were inoculated with PCB-contaminated sediments collected from a water channel leaving a former chemical factory (Strazske, Slovak Republic). Total RNA and DNA were extracted after six months of continuous growth. The first goal was to identify the members of the dechlorinating bacterial guild, as well as identifying the enzymes which were involved in the reductive dehalogenation of the PCBs. A second goal was to identify environmental variables that influence the biological removal of PCBs in the contaminated sites. The anaerobic conditions imposed to the microcosms resulted in the enrichment of putative PCB dechlorinators (Dehalococcoides sp. as well as members of the Chloroflexi class). T-RFLP analysis of the initial bacterial communities and bacterial consortia in microcosms showed a clear shift in their respective compositions. Two microcosms samples are currently being analyzed in details using a cloning-sequencing strategy, leading to a sequence analysis and the construction of phylogenetic trees. The analysis of the PCB congeners present in the microcosms is currently under way. In parallel, a comprehensive list of all dehalogenase sequences found in databases was produced. Based on these sequences, new sets of degenerated primers were designed for the detection of putative genes involved in biodegradation of highly chlorinated PCBs.

2010

Divergent PCB organohalide-respiring consortia enriched from the efflux channel of a former Delor manufacturer in Eastern Europe

Luiz Felippe De Alencastro, Christof Holliger, Martina Praveckova, Pierre Rossi

Polychlorinated biphenyl (PCB) organohalide-respiring communities from the efflux channel of a former Delor manufacturer in Eastern Slovakia were assessed using metagenomic, statistical and cultivation-adapted approaches. Multivariate analysis of environmental factors together with terminal restriction fragment length polymorphisms of the bacterial communities in the primary sediments revealed both temporal and spatial heterogeneity in the distribution of microbial populations, which reflects the dynamic pattern of contamination and altered conditions for biodegradation activity along the channel. Anaerobic microcosms were developed from eight sediments sampled along the channel, where high concentrations of PCBs – from 6.6 to 136 mg/kg dry weight, were measured. PCB dehalorespiring activity, congruent with changes in the microbial composition in all microcosms, was detected. After 10 months of cultivation, the divergently evolved consortia achieved up to 35.9 percent reduction of the total PCB concentration. Phylogenetic-analysis of the active Chloroflexi-related organohalide respiring bacteria by partial sequencing of 16S rRNA genes in cDNA from microcosms with the highest PCB dechlorination activity revealed diverse and unique complexity of the populations. The predominant organohalide respirers were either affiliated with Dehalococcoides sp. and Dehalococcoides-like group (DLG) organisms or were composed of currently unknown distant clades of DLG bacteria. The present study should encourage researchers to explore the full potential of the indigenous PCB dechlorinating populations to develop effective bioremediation approaches that can perform the complete mineralization of PCBs in polluted environments.

Elsevier2015

WHO IS INTERESTED IN THE REDUCTIVE DECHLORINATION OF POLYCHLORINATED BIPHENYLS (PCBs)?

Christof Holliger, Martina Praveckova, Pierre Rossi

2010