Publications de Christof Holliger

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IntroductionDesulfitobacterium hafniense was isolated for its ability to use organohalogens as terminal electron acceptors via organohalide respiration (OHR). In contrast to obligate OHR bacteria, Desulfitobacterium spp. show a highly versatile energy meta ...

Chloroethenes such as tetrachloroethene (PCE) and trichloroethene (TCE) are among the most prevalent contaminants in groundwater due to their extensive use in industrial processes. In situ bioremediation (ISB) is an attractive technology for removal of these compounds. It relies on an anaerobic process in which specialized bacteria obtain energy for growth using chloroethenes as an electron acceptor via organohalide respiration. Engineered bioremediation is achieved by stimulating these microorganisms throu

Numerous industries and facilities have been using chlorinated ethenes (CEs) as non-flammable solvents during manufacturing. Massive usage, careless handling and storage, spills and leakages made them one of the most frequent aquifer contaminants. CEs are reductively dechlorinated under anaerobic conditions by dehalorespiring bacteria leading to the formation of harmless ethene as end product. The geographical pattern and the main ecological drivers of the microbial communities involved in these dehalorespi

Bioremediation of tetra-and trichloroethene-contaminated aquifers is requently hampered due to incomplete dechlorination to the more toxic dichloroethene (DCE) and vinyl chloride (VC), indicating insufficient knowledge about the biological mechanisms relat ...

Background/Objectives. Chloroethenes such as tetrachloroethene (PCE) and trichloroethene (TCE) are among the most prevalent contaminants in groundwater due to their extensive use in industrial processes. In situ bioremediation (ISB) is an attractive technology for the removal of these compounds. It has been widely used for treatment of chloroethene plumes and recent studies have shown promising results for removal of dense non aqueous phase liquids (DNAPLs). However, application of source zone ISB is still

A combined process for carotenoids extraction and efficient bioenergy recovery from the wet microalgae biomass is proposed. High added-value products could thus be extracted prior a hydrothermal gasification of the algal biomass into synthetic natural gas. ...

Intensive nutrient removal from wastewater in anaerobic–aerobic systems using granular sludge should rely on optimal balances at biofilm and microbial ecology levels. This study targets the impacts of reactor characteristics and fluctuations in operation c ...

Microalgae represent an attractive source of biomass for biofuels and chemicals production since they can have higher energy yields per area than conventional biomass crops and can be grown on marginal land using waste, saline, or brackish water. Their use can thus avoid the food-fuel competition for land and water, resulting in major economic and social benefits. At the present stage however, significant developments are requested for making microalgae-to-biofuels processes technologically and economically

Introduction Aerobic granular sludge used for intensified biological wastewater treatment is based on fast-settling mobile biofilms with a gel-like consistence, called “granules”, formed from activated sludge flocs (Seviour et al. 2012). Fundamental aspects of the mechanisms of microbial selection and self-immobilisation as spherical biofilms have recently been studied in detail (Weissbrodt et al. 2013). In an approach combining biofilm engineering, molecular microbial ecology, and laser scanning microscopy

Enhanced reductive dehalogenation is an attractive in situ treatment technology for chlorinated contaminants. The process includes two acid-forming microbial reactions: fermentation of an organic substrate resulting in short-chain fatty acids, and dehalogenation resulting in hydrochloric acid. The accumulation of acids and the resulting drop of groundwater pH are controlled by the mass and distribution of chlorinated solvents in the source zone, type of electron donor, alternative terminal electron acceptor

A process based on partial nitrification and recirculation into the anaerobic digester was studied to remove nitrogen from digested manure and thus reduce enhanced gaseous ammonia emissions due to on-farm biogas production. An anaerobic reactor representin ...

Organohalide respiration (OHR) is a bacterial anaerobic respiratory metabolism dedicated to use halogenated compounds as terminal electron acceptors. OHR bacteria are strictly anaerobic microorganisms which use reductive dehalogenases (RdhA) as key enzymes in this respiration process (1,2). Dehalobacter restrictus, an obligate OHR bacterium has been shown to use exclusively tetra- (PCE) and trichloroethene (TCE) as electron acceptors. The PCE RdhA (so called PceA) has been characterized previously (3). D. r

Chlorinated ethenes (CEs), such as perchloroethene (PCE) and trichloroethene (TCE), are one of the most common class of groundwater contaminants. Aquifers are considered nowadays as dynamic ecosystems, showing multiple interactions between the physical, chemical and biotic components. The assessment of the intrinsic contaminant biodegradation capacities of these complex ecosystems was carried out using an integrative methodology, combining both molecular microbial ecology and water geochemical data. The bio

Organohalide respiration (OHR) is an anaerobic metabolism by which bacteria conserve energy from the use of organohalide molecules as terminal electron acceptors. Because most organohalides of anthropogenic origin are persistent pollutants, the study of bacteria capable of OHR (OHRB) has a strong environmental interest. OHRB appear in three major phyla (Firmicutes, Proteobacteria and Chloroflexi) and encode at least one reductive dehalogenase (RdhA) in their genomes. RdhA enzymes are the key catalytic subun

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 environme ...

• Aerobic granular sludge (AGS) is a promising alternative wastewater treatment to the conventional activated sludge system. As AGS has enhanced settling abilities and provides different redox conditions across the granules at the same time, the processes ...

Chlorinated ethenes, frequently encountered contaminants in groundwater, are often found to be incompletely dechlorinated to dichloroethene and vinyl chloride, more toxic products that accumulate in the aquifer. Some of the concerns in designing remediation approaches based on biological dechlorination are i) the presence of bacteria capable of completely reducing chlorinated ethenes, and ii) the competition events for available electron donors between classical biogeochemical processes and the reductive de

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 t

Respiratory complex I is a well-known player in aerobic respiration; it couples the transfer of two electrons from NADH to ubiquinone alongside with proton pumping. Bacterial complex I is usually composed of fourteen subunits forming three different modules [1]. While the full-size version of the complex is the most commonly found among eubacteria, an 11-subunit version, lacking the NADH-oxidizing module, is surprisingly widely distributed [2]. This version, considered as ancestral [2,3], was initially desc

Christof Holliger

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Proteome adaptations of the organohalide-respiring Desulfitobacterium hafniense strain DCB-2 to various energy metabolisms

Utilization of silicate minerals for pH control during in situ bioremediation of chlorinated solvent

Bacterial communities associated with chloroethene–contaminated aquifers present both geographical isolation and strong correlations to local environmental variables

Validation of an integrative methodology to assess and monitor reductive dechlorination of chlorinated ethenes in contaminated aquifers

Utilization of Silicate Minerals for pH Control during In Situ Bioremediation of Chlorinated Solvents

Extraction of carotenoids from Chlorella vulgaris using green solvents and syngas production from residual biomass

Linking bacterial population dynamics and nutrient removal in the granular sludge biofilm ecosystem engineered for wastewater treatment

Towards the sustainable cultivation of microalgae for the production of biofuels and added-value chemicals

The biofilm granulation mechanisms depend on the predominant bacterial populations involved

Effect of heterogeneity on enhanced reductive dechlorination: Analysis of remediation efficiency and groundwater acidification

Nitrogen removal from digested manure in a simple one-stage process

The genome of Dehalobacter restrictus - high gene redundancy for a restricted metabolism

Assessment of bioremediation potential and monitoring of biological reductive dechlorination in sites contaminated with chlorinated ethenes

RDHK Family, Regulators dedicated to Organohalide Respiration - Sequence Diversity and Functional Prediction

RDHK Family, Regulators dedicated to Organohalide Respiration - Sequence Diversity and Functional Prediction

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

Evolution of microbial communities and nutrient removal performances in aerobic granular sludge sequencing batch reactor during change of substrate

An ecological approach for understanding the reductive dechlorination process of chlorinated ethenes in contaminated aquifers

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

Conditional essentiality of a complex I-like enzyme in strict anaerobes: the case of Desulfitobacterium