Gregor Hommes

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The endocrine disrupting chemical nonylphenol (NP) is a technical product which consists of a complex mixture of nonylphenols with different alkyl side-chain isomers. Since the bio-degradation of each NP isomer may lead to its own range of metabolites, the isolation and identification of transformation products is very difficult. In order to overcome this(More)
The degradation of the 4(3',5'-dimethyl-3'-heptyl)-phenol (p353NP)nonylphenol isomer in cultures of Sphingomonas TTNP3 supplemented withthe technical mixture of nonylphenol was first assessed. Then the radioactive andnon-labelled form of these diastereomers were both synthesised. The radioactiveisomers were synthesised using [ring-U-14C]-labelled phenol(More)
A new system based on laccase-modified silica nanoparticles has been developed and tested for its ability to degrade a major endocrine disrupting chemical, 4,4'-isopropylidenediphenol (bisphenol A). The nanoparticles have been produced using the Stöber method and characterized using scanning electron microscopy, dynamic light scattering and zeta-potential(More)
Enyzme immobilization on solid surfaces is one of the most relevant methods to improve enzyme activity and stability under harsh conditions over extended periods. A typically interesting application is the immobilization of laccases, multicopper enzymes oxidizing aromatic compounds, to solid surfaces in order to develop valuable tools for the elimination of(More)
The degradation of radiolabeled 4(3′,5′-dimethyl-3′-heptyl)-phenol [nonylphenol (NP)] was tested with resting cells of Sphingomonas sp. strain TTNP3. Concomitantly to the degradation of NP, a metabolite identified as hydroquinone transiently accumulated and short-chain organic acids were then produced at the expense of hydroquinone. Two other radiolabeled(More)
This paper evaluates the use of upflow anaerobic sludge bed (UASB) bioreactors (30 degrees C, pH=7.0) to remove selenium oxyanions from contaminated waters (790 microg Se L(-1)) under methanogenic and sulfate-reducing conditions using lactate as electron donor. One UASB reactor received sulfate at different sulfate to selenate ratios, while another UASB was(More)
The biotransformation of the nonylphenol isomer [ring-U-14C]-4-(3',5'-dimethyl-3'-heptyl)-phenol (4-353-NP, consisting of two diastereomers) was studied in soybean and Agrostemma githago cell suspension cultures. With the A. githago cells, a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v) was used, in order to produce higher concentrations(More)
The removal of recalcitrant chemicals in wastewater treatment systems is an increasingly relevant issue in industrialized countries. The elimination of persistent xenobiotics such as endocrine-disrupting chemicals (EDCs) emitted by municipal and industrial sewage treatment plants remains an unsolved challenge. The existing efficacious physico-chemical(More)
Immobilization is an important method to increase enzyme stability and allow enzyme reuse. One interesting application in the field of environmental biotechnology is the immobilization of laccase to eliminate phenolic contaminants via oxidation. Fumed silica nanoparticles have interesting potential as support material for laccase immobilization via(More)
Considerable effort has been dedicated to the chemical depolymerization of lignin, a biopolymer constituting a possible renewable source for aromatic value-added chemicals. However, these efforts yielded limited success up until now. Efficient lignin conversion might necessitate novel catalysts enabling new types of reactions. The use of multiple catalysts,(More)