Publications by Christof Holliger

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Corrinoids (derivatives of vitamin B12) are an essential cofactor of reductive dehalogenases, the key enzymes involved in the environmental-friendly process of organohalide respiration (OHR). However, genomic and physiological analyses of obligate OHR bacteria (such as Dehalobacter and Dehalococcoides) have delivered contrasting results on the ability of de novo corrinoid biosynthesis. This raised the question of the source of corrinoids for obligate OHR bacteria in the environment and their biosynthesis/sc

Introduction: Corrinoids are an essential cofactor of reductive dehalogenases, the key enzymes of organohalide respiration (OHR). Dehalobacter restrictus strain PER-K23 is an obligate OHR bacterium able to conserve energy with tetrachloroethene, but is unable to de novo synthesize corrinoids. In contrast, genome analysis of D. restrictus revealed the presence of the complete corrinoid biosynthesis pathway. Objectives: To understand the corrinoid metabolism of D. restrictus at the level of biosynthesis, regu

Aerobic granular sludge (AGS) consists of a microbial consortium that has an important role in wastewater treatment. This study investigates AGS microorganisms cultivated in a laboratory-scale sequencing batch reactor. Metagenomic sequencing was conducted ...

During the past 20 years, aerobic granular sludge (AGS) has been extensively studied with the aim to develop an attractive alternative to conventional activated sludge for wastewater treatment. The phosphate-accumulating organism (PAO) Candidatus ‘Accumulibacter phosphatis’ is often found with significant abundance in AGS as well as in other enhanced biological phosporus removal (EPBR) systems. Although they have never been isolated in pure culture, members of this bacterial genus appear to be genetically a

Dehalobacter restrictus strain PER-K23 is an obligate organohalide respiring bacterium, which displays extremely narrow metabolic capabilities. It grows only via coupling energy conservation to anaerobic respiration of tetra- and trichloroethene with hydro ...

Tetra- (PCE) and trichloroethene (TCE) are major groundwater pollutants due to their extensive industrial use. Several anaerobic bacteria have been isolated using chloroethenes as terminal electron acceptor. Most of these bacteria dechlorinate PCE and TCE to cis-1,2-dichloroethene (cis-1,2-DCE). A few Dehalococcoides strains are able to dechlorinate cis-1,2-DCE and vinyl chloride (VC) to the ethene. Identification of the key enzyme, the reductive dehalogenase, has revealed a new class of enzymes containing

Recent analysis of a set of reductive dehalogenases revealed that sequence similarity and substrate specificity are not correlated, making functional prediction from sequences difficult (1). To this respect, several enrichment cultures were investigated for their distinct dechlorination potential of tetrachloroethene (PCE). Indeed, SL2-PCEb, an enrichment culture dominated by Sulfurospirillum spp., was shown to stepwise dechlorinate PCE to TCE and cis-DCE, suggesting the successive involvement of two dechlo

The aerobic granular sludge process optimization is linked to the interdependence of process, biofilm and microbial scales. Stable dense fast-settling granules composed of bacterial guilds for the simultaneous removal of carbonaceous, phosphorous and nitrogenous loads are desired. In this study, two activated inoculation sludges were used to start-up aerobic granular sludge bubble column sequencing batch reactors, one from a wastewater treatment plant (WWTP) that removes carbon biologically, nitrifies, and

Massive usage, along with careless handling, storage, spills, and leakages made chloroethenes (CEs) one of the most abundant classes of groundwater contaminants. Anaerobic organohalide respiring bacteria (OHRB) can couple reductive dechlorination of CEs wi ...

Treatment of micropollutants such as pharmaceuticals and pesticides in municipal wastewater is challenging due to their very low concentrations (ng/l to µg/l), their relatively low biodegradability, and their different physico-chemical characteristics. One potential way to improve micropollutant biodegradation in wastewater treatment plant (WWTP) effluent is by using microorganisms such as white-rot fungi that produce powerful unspecific oxidative exo-enzymes (laccase, peroxidase) that are able to oxidize s

Chlorinated ethenes (CEs) pose a long-lasting risk for humans and the environment. Nowadays, they are the major groundwater contaminant worldwide and are of particular concern since they form a dense non-aqueous phase liquid (DNAPL). Reductive dehalogenation of the CEs to the non-toxic end-products ethane and ethene is used for nearly twenty years as the most efficient and used remediation technique called enhanced reductive dehalogenation (ERD). However, in some cases the reduction of CEs is halted to 1,2-

Soil pollution with hexachlorocyclohexane (HCH) has caused serious environmental problems. Here we describe the targeted degradation of all HCH isomers by applying the aerobic bacterium Sphingobium indicum B90A. In particular, we examined possibilities for ...

To locate a high-dose point hexachlorocyclohexane (HCH)-contaminated site, to identify HCH-degrading bacteria in it and assay HCH-decontamination by biostimulation. Methods and Results: Bacteria were isolated by serial dilution method from HCH-contaminate ...

Mine tailings are a serious threat to the environment and public health. Remediation of these residues can be carried out effectively by the activation of specific microbial processes. This article presents detailed information about temporal changes in ba ...

TsrE, a 32kDa sulfur-transferase with two rhodanese domains, was identified as a result of its over-expression during anaerobic tetrachloroethene respiration by the obligate gram-positive anaerobe Desulfitobacterium hafniense. The tsrE gene is part of an operon containing the classical ABCD gene arrangement belonging to the DMSO reductase family, and showing homology with the thiosulfate reductase operon (tsr). Detailed analysis of TsrE sequence features revealed the presence of a N-terminal lipo-box sugges

Many organic compounds present at low concentrations in municipal wastewater, such as various pharmaceuticals and biocides, are recalcitrant in conventional wastewater treatment plants (WWTPs). To improve their biodegradation, oxidoreductase enzymes such a ...

The corrinoid cofactor is essential to organohalide respiration (OHR) as key element in virtually all reductive dehalogenases. Desulfitobacteria, and more particularly D. hafniense, represent a group of versatile OHR bacteria able to produce corrinoids de novo, as initially discovered in the genome of D. hafniense Y51 (1). Since then several desulfitobacteria genomes have been sequenced revealing that the corrinoid metabolism (biosynthesis, transport, regulation) represents a conserved trait in a highly var

We developed standard curves based on plasmids containing a 16S rRNA gene of a member of one of the three genera Dehalobacter, Desulfitobacterium, and Dehalococcoides. A large difference in amplification efficiency between the standard curves was observed ranging from 1.5 to 2.0. The total eubacterial 16S rRNA gene copy number determined in a sample DNA by using eubacterial primers and the three standard curves led to differences in the estimated copy numbers of a factor up to 73. However, the amplification

Aerobic granular sludge (AGS) is a promising alternative wastewater treatment to the conventional activated sludge system allowing space and energy saving. Basic understanding of AGS has mainly been obtained using simple wastewater containing acetate and p ...

Christof Holliger

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Corrinoid auxotrophy in the obligate organohalide respiring Dehalobacter restrictus

Corrinoid auxotrophy in the obligate organohalide-respiring Dehalobacter restrictus

Corrinoid Auxotrophy in the Obligate Organohalide-Respiring Dehalobacter restrictus strain PER-K23

Microbial genome collection of aerobic granular sludge cultivated in sequencing batch reactors using different carbon source mixtures

Phage-dependent variability of Candidatus "Accumulibacter phosphatis" populations in aerobic granular sludge

The restricted metabolism of the obligate organohalide respiring bacterium Dehalobacter restrictus: lessons from tiered functional genomics

Indication for horizontal transfer of reductive dehalogenase genes

Functional characterization of a new tetrachloroethene reductive dehalogenase of Sulfurospirillum spp. identified in mixed cultures

The choice of inoculum is key for aerobic granular sludge process development

Ecology and Biogeography of Bacterial Communities Associated with Chloroethene-Contaminated Aquifers

Treatment of micropollutants in municipal wastewater using white-rot fungi

Multidisciplinary approach for evaluation of the complete removal of chloroethenes in contaminated aquifer

Enhanced biodegradation of hexachlorocyclohexane (HCH) in contaminated soils via inoculation with Sphingobium indicum B90A

Proposal of biostimulation for hexachlorocyclohexane (HCH)-decontamination and characterization of culturable bacterial community from high-dose point HCH-contaminated soils

Temporal evolution of bacterial communities associated with the in situ wetland-based remediation of a marine shore porphyry copper tailings deposit

TsrE: a sulfur-transferase involved in various anaerobic respiration pathways ?

Influence of treatment conditions on the oxidation of micropollutants by Trametes versicolor laccase

Regulation of the Corrinoid Metabolism in Desulfitobacteria

Development of a real-time PCR method for quantification of the three genera Dehalobacter, Dehalococcoides, and Desulfitobacterium in microbial communities

Multistability and Reversibility of Aerobic Granular Sludge Microbial Communities Upon Changes From Simple to Complex Synthetic Wastewater and Back