Publications de Christof Holliger

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Microalgal cultures represent a promising alternative source of biomass for biofuel and chemicals production, since they can reach 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, resulting in major economic and social benefits. At the present stage however, major developments are needed for making microalgae-to-biofuels process technologically and economically f

The PyroTRF-ID bioinformatics methodology (http://bbcf.epfl.ch/PyroTRF-ID/) was developed to combine pyrosequencing and T-RFLP for describing microbial communities and identifying T-RFs by comparison of experimental and digital T-RFLP profiles obtained from the same biological samples. DNA extracts were subjected to amplification of the 16S rRNA gene pool, T-RFLP with the HaeIII restriction enzyme, 454 tag encoded FLX amplicon pyrosequencing, and PyroTRF-ID analysis. Digital T-RFLP profiles were generated f

Introduction Microalgae culture to be effective as feedstock for bio-energy production needs to overcome constraining biotechnological, technological and economic factors [1]. In order to establish an economically viable process, the co-production of renewable fuels along with bioproducts (for pharmaceutical, food, feed, chemicals industry, etc.), in a biorefinery concept has been considered [2]. In this concern the deal of the SunCHem project is to produce methane from the catalytic hydrothermal gasificati

Aerobic granular sludge is a biological wastewater treatment process in which a microbial community forms a granular biofilm. The role of Candidatus Accumulibacter in the production of a biofilm matrix composed of extracellular polymeric substances was stu ...

Numerous industries and facilities have been using chlorinated ethenes (CEs) as non-flammable solvents since the beginning of the 20th century. These compounds are known to persist in the environment, exerting adverse effects. They have been considered for a long time as totally resistant to any form of microbial degradation. Advances in this field since the 1980’s showed that several bacteria can couple the reductive dechlorination of CEs to energy conservation in a process called dehalorespiration. Object

Estrogenic substances discharged from wastewater treatment plants have been detected in surface sediments of receiving waters, but little is known of their vertical migration through buried sediments and their potential to contaminate subsurface waters. Th ...

Municipal wastewaters are contaminated by a wide range of chemicals, from surfactants to heavy metals, including pharmaceutical residues, personal care products, various household chemicals, and biocides/pesticides. Their release into the environment, wher ...

One of the aims of wastewater treatment is the removal of phosphorus before the water is discharged into the environment. Since phosphorus concentrations in wastewater exceed the requirement of bacterial growth, biological phosphorus removal is based on the ability of a group of microorganisms, named “Polyphosphate Accumulating Organisms” (PAO), to store large quantities of intracellular phosphate in form of polyphosphate. In this study, we are focusing on the PAO actively involved in bioreactors operated w

Background The NADH:ubiquinone oxidoreductase (Nuo) is an assembly of proteins also known as complex I. It is the entry point for highly energetic electrons in the classical aerobic respiration process as it couples the transfer of two electrons from NADH to ubiquinone with proton pumping resulting in the establishment of a proton mortice force. It was assumed that to fulfil its function, the complex must contain at least 14 subunits. Yet the presence of an 11-subunit version of complex I as detected in gen

Aerobic granules are quasi-spherical biofilms mainly composed of self-immobilized mixed microbial communities. The application of aerobic granules to treat domestic and low-strength industrial wastewaters is gaining attention because granules can accommodate high biomass concentrations and this translates into small foot-print treatment reactors. For robust application of this novel treatment technology, aerobic granules should be physically stable, and to account for the removal of the desired contaminants

For the successful application of aerobic granules in wastewater treatment, granules containing an appropriate microbial assembly able to remove contaminants should be retained and propagated within the reactor. To manipulate and/or optimize this process, ...

Methanogenesis from main methane precursors H2/CO2 and acetate was investigated in a temperature range of 2–70 °C using sediments from Lake Baldegg, Switzerland. Psychrophilic, psychrotrophic, mesophilic, and thermophilic methanogenic microbial communities ...

Halogenated organic compounds (so-called organohalides) represent one of the major class of groundwater pollutants. The exploration of how organohalides are used as energy source is important in terms of ecosystem remediation but is also essential for the complete understanding of microbial metabolic interactions in the environment. Organohalide respiration (OHR) is a bacterial anaerobic process in which chlorinated compound, e.g. tetrachloroethene (PCE), is used as terminal electron acceptor. In the presen

Recently, it was shown that ground silicate minerals are a potentially suitable pH buffering material for contaminated soils undergoing acidification, for example due to acid mine leachate and coal pile runoff infiltration, as well as during the degradation of chlorinated ethenes (Lacroix et al., 2012, Doi: 10.1007/s11270-011-1058-4). Compared to traditional buffering methods, such as the circulation of an alkaline solution, silicate minerals are appealing because they are long-term sources of buffering cap

The potential of laccase-mediator systems (LMS) for the removal and detoxification of two wastewater micropollutants, the antibiotic sulfamethoxazole (SMX) and the herbicide isoproturon (IPN), was assessed. The influence of various parameters on micropollu ...

Biological wastewater treatment by aerobic granular sludge biofilms offers the possibility to combine carbon (COD), nitrogen (N) and phosphorus (P) removal in a single reactor. Since denitrification can be affected by suboptimal dissolved oxygen concentrat ...

In oxidative phosphorylation, respiratory complex I serves as an entry point in the electron transport chain for electrons generated in catabolic processes in the form of NADH. An ancestral version of the complex, lacking the NADH-oxidising module, is enco ...

Numerous industries have been using chlorinated ethenes (CEs), mainly tetrachlorethene and trichloroethene, as non-flammable solvents since the beginning of the 20th century. Massive usage, along with careless handling and storage, made CEs one of the most abundant classes of aquifer contaminants. Porous aquifers are dynamic ecosystems showing complex interactions between physical, chemical and biotic components. These environments are inherently extremely heterogeneous in their structure and composition in

Chloroethenes such as tetrachloroethene (PCE) and trichloroethene (TCE) are among the most prevalent contaminants in groundwater. Because of their low aqueous solubility, PCE and TCE are often present as dense non aqueous phase liquid (DNAPL) that can act as a long term source of groundwater contamination. In situ enhanced bioremediation is an attractive technology for removal of PCE and TCE. It relies on a process called dehalorespiration in which dehalogenating bacteria reduce PCE to ethene, which is a ha

Christof Holliger

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Towards the sustainable cultivation of microalgae to produce renewable biofuels and added-value chemicals

PyroTRF-ID: a novel bioinformatics methodology for the affiliation of terminal-restriction fragments using 16S rRNA gene pyrosequencing data

Microalgal carotenoid recovery in a biorefinery approach

Multiple extracellular polymeric substance pathways transcribed by Accumulibacter and the flanking community during aerobic granule formation and after influent modification

Biogeography and spatial variability of bacterial communities associated with chloroethene – contaminated aquifers

Hydroxylated Metabolites of β- and δ-Hexachlorocyclohexane: Bacterial Formation, Stereochemical Configuration, and Occurrence in Groundwater at a Former Production Site

A review of the fate of micropollutants in wastewater treatment plants

Imaging the aerobic granular sludge microbial community using light-sheet fluorescence micros

Involvement of respiratory complex I in organohalide respiration?

The carbon source governs the population dynamics of phosphate accumulating organisms in aerobic granules

Aerobic Granules: Microbial Landscape and Architecture, Stages, and Practical Implications

Influence of temperature and high acetate concentrations on methanogenensis in lake sediment slurries

Anaerobic Biodegradation of organohalide pollutants: a crucial step towards the elucidation of proteins involved

Numerical modeling of field scale application of ground silicate minerals for groundwater pH buffering

Sulfamethoxazole and isoproturon degradation and detoxification by a laccase-mediator system: Influence of treatment conditions and mechanistic aspects

Optimized aeration strategies for nitrogen and phosphorus removal with aerobic granular sludge

BIOGEOGRAPHY AND SPATIAL VARIABILITY OF BACTERIAL COMMUNITIES ASSOCIATED WITH CHLOROETHENE – CONTAMINATED AQUIFERS

Conditional essentiality of the 11-subunit complex I-like enzyme in strict anaerobes: the case of Desulfitobacterium hafniense strain DCB-2

BACTERIAL COMMUNITIES IN A CONTAMINATED AQUIFER: INFLUENCE OF ENVIRONMENTAL VARIABLES

Buffering agent for pH control during in situ bioremediation of chlorinated solvent source zones