Lynn Vanhaecke

Human Colon Microbiota Transform Polycyclic Aromatic Hydrocarbons to Estrogenic Metabolites

Ingestion is an important exposure route for polycyclic aromatic hydrocarbons (PAHs) to enter the human body. Although the formation of hazardous PAH metabolites by human biotransformation enzymes is well documented, nothing is known about the PAH transformation potency of human intestinal microbiota. Using a gastrointestinal simulator, we show that human intestinal microbiota can also bioactivate PAHs, more in particular to estrogenic metabolites. PAH compounds are not estrogenic, and indeed, stomach and small intestine digestions of 62.5 nmol naphthalene, phenanthrene, pyrene, and benzo(a)pyrene showed no estrogenic effects in the human estrogen receptor bioassay. In contrast, colon digests of these PAH compounds displayed estrogenicity, equivalent to 0.31, 2.14, 2.70, and 1.48 nmol 17α-ethynylestradiol (EE2), respectively. Inactivating the colon microbiota eliminated these estrogenic effects. Liquid chromatography–mass spectrometry analysis confirmed the microbial PAH transformation by the detection of PAH metabolites 1-hydroxypyrene and 7-hydroxybenzo(a)pyrene in colon digests of pyrene and benzo(a)pyrene. Furthermore, we show that colon digests of a PAH-contaminated soil (simulated ingestion dose of 5 g/day) displayed estrogenic activity equivalent to 0.58 nmol EE2, whereas stomach or small intestine digests did not. Although the matrix in which PAHs are ingested may result in lower exposure concentrations in the gut, our results imply that the PAH bioactivation potency of colon microbiota is not eliminated by the presence of soil. Moreover, because PAH toxicity is also linked to estrogenicity of the compounds, the PAH bioactivation potency of colon microbiota suggests that current risk assessment may underestimate the risk from ingested PAHs.

Residue analysis: future trends from a historical perspective.

A residue is a trace (microg kg(-1), ng kg(-1)) of a substance, present in a matrix. Residue analysis is a relatively young discipline and a very broad area, including banned (A) substances as well as registered veterinary medicinal products (B substances). The objective of this manuscript is to review future trends in the analysis of residues of veterinary drugs in meat producing animals out of historical perspectives. The analysis of residues in meat producing animals has known a tremendous evolution during the past 35-40 years. In the future, it can be foreseen that this evolution will proceed in the direction of the use of more and more sophisticated and expensive machines. These apparatus, and the necessary human resources for their use, will only be affordable for laboratories with sufficient financial resources and having guarantee for a sufficient throughput of samples.

Degradation of acetaminophen by Delftia tsuruhatensis and Pseudomonas aeruginosa in a membrane bioreactor

The incidence and fate of pharmaceuticals in the water cycle impose a growing concern for the future reuse of treated water. Because of the recurrent global use of drugs such as Acetaminophen (APAP), an analgesic and antipyretic drug, they are often detected in wastewater treatment plant (WWTP) effluents, receiving surface waters and drinking water resources. In this study, the removal of APAP has been demonstrated in a membrane bioreactor (MBR) fed with APAP as the sole carbon source. After 16 days of operation, at a hydraulic retention time (HRT) of 5 days, more than 99.9% removal was obtained when supplying a synthetic WWTP effluent with 100 μg APAP L(-1). Batch experiments indicated no sorption of APAP to the biomass, no influence of the WWTP effluent matrix, and the capability of the microbial consortium to remove APAP at environmentally relevant concentrations (8.3 μg APAP L(-1)). Incubation with allylthiourea, an ammonia monooxygenase inhibitor, demonstrated that the APAP removal was mainly associated with heterotrophic bacteria and not with the ammonia-oxidizing bacteria. Two APAP degrading strains were isolated from the MBR biomass and identified as Delftia tsuruhatensis and Pseudomonas aeruginosa. During incubation of the isolates, hydroquinone - a potentially toxic transformation product - was temporarily formed but further degraded and/or metabolized. These results suggest that the specific enrichment of a microbial consortium in an MBR operated at a high sludge age might be a promising strategy for post-treatment of WWTP effluents containing pharmaceuticals.

Disposition of soy isoflavones in normal human breast tissue

BACKGROUND Despite decades of research on the relation between soy and breast cancer, questions regarding the absorption, metabolism, and distribution of isoflavones in breast tissue largely remain unanswered. OBJECTIVE We evaluated the potential health effects of isoflavone consumption on normal breast tissue; isoflavone concentrations, metabolites, and biodistribution were investigated and compared with 17beta-estradiol exposure. DESIGN In this dietary intervention study, healthy women were randomly allocated to a soy milk (n = 11; 16.98-mg genistein and 5.40-mg daidzein aglycone equivalents per dose), soy supplement (n = 10; 5.27-mg genistein and 17.56-mg daidzein aglycone equivalents per dose), or control (n = 10) group. After a run-in period > or = 4 d, 3 doses of soy milk or soy supplements were taken daily for 5 d before an esthetic breast reduction. Blood and breast biopsies were collected during surgery and analyzed with liquid chromatography-tandem mass spectrometry. RESULTS After soy administration, genistein and total daidzein concentrations, which were expressed as aglycone equivalents, ranged from 135.1 to 2831 nmol/L and 105.1 to 1397 nmol/L, respectively, in hydrolyzed serum and from 92.33 to 493.8 pmol/g and 22.15 to 770.8 pmol/g, respectively, in hydrolyzed breast tissue. The major metabolites identified in nonhydrolyzed samples were genistein-7-O-glucuronide and daidzein-7-O-glucuronide, with an overall glucuronidation of 98%. Total isoflavones showed a breast adipose/glandular tissue distribution of 40:60, and their mean (+/-SEM) derived 17beta-estradiol equivalents toward estrogen receptor beta were 21 +/- 4-fold and 40 +/- 10-fold higher than the 17beta-estradiol concentrations in adipose (0.283 +/- 0.089 pmol/g, P < 0.001) and glandular (0.246 +/- 0.091 pmol/g, P = 0.001) fractions, respectively. CONCLUSION After intake of soy milk and soy supplements, isoflavones reach exposure levels in breast tissue at which potential health effects may occur.

Diclofenac Oxidation by Biogenic Manganese Oxides

Diclofenac, a nonsteroidal anti-inflammatory drug, is one of the most commonly detected pharmaceuticals in sewage treatment plant (STP) effluents. In this work, biologically produced manganese oxides (BioMnOx) were investigated to remove diclofenac. At neutral pH, the diclofenac oxidation with BioMnOx was 10-fold faster than with chemically produced MnO(2). The main advantage of BioMnOx over chemical MnO(2) is the ability of the bacteria to reoxidize the formed Mn(2+), which inhibits the oxidation of diclofenac. Diclofenac-2,5-iminoquinone was identified as a major transformation product, accounting for 5-10% of the transformed diclofenac. Except for 5-hydroxydiclofenac, which was identified as an intermediate, no other oxidation products were detected. Diclofenac oxidation was proportional to the amount of BioMnOx dosed, and the pseudo first order rate constant k was 6-fold higher when pH was decreased from 6.8 to 6.2. The Mn(2+) levels remained below the drinking water limit (0.05 mg L(-1)), thus indicating the efficient in situ microbiological regeneration of the oxidant. These results combined with previous studies suggest the potential of BioMnOx for STP effluent polishing.

Biogenic metals for the oxidative and reductive removal of pharmaceuticals, biocides and iodinated contrast media in a polishing membrane bioreactor

Pharmaceutical and personal care products, biocides and iodinated contrast media (ICM) are persistent compounds, which appear in ng to μg L(-1) in secondary effluents of sewage treatment plants (STPs). In this work, biogenic metals manganese oxides (BioMnOx) and bio-palladium (Bio-Pd) were applied in lab-scale membrane bioreactors (MBR) as oxidative and reductive technologies, respectively, to remove micropollutants from STP-effluent. From the 29 substances detected in the STP-effluent, 14 were eliminated in the BioMnOx-MBR: ibuprofen (>95%), naproxen (>95%), diuron (>94%), codeine (>93%), N-acetyl-sulfamethoxazole (92%), chlorophene (>89%), diclofenac (86%), mecoprop (81%), triclosan (>78%), clarithromycin, (75%), iohexol (72%), iopromide (68%), iomeprol (63%) and sulfamethoxazole (52%). The putative removal mechanisms were the chemical oxidation by BioMnOx and/or the biological removal by Pseudomonas putida and associated bacteria in the enriched biofilm. Yet, the removal rates (highest value: 2.6 μg diclofenac L(-1) d(-1)) need to improve by a factor 10 in order to be competitive with ozonation. ICM, persistent towards oxidative techniques, were successfully dehalogenated with a novel reductive technique using Bio-Pd as a nanosized catalyst in an MBR. Iomeprol, iopromide and iohexol were removed for >97% and the more recalcitrant diatrizoate for 90%. The conditions favorable for microbial H(2)-production enabling the charging of the Pd catalyst, were shown to be important for the removal of ICM. Overall, the results indicate that Mn oxide and Pd coupled to microbial catalysis offer novel potential for advanced water treatment.

Rapid quantification of pharmaceuticals and pesticides in passive samplers using ultra high performance liquid chromatography coupled to high resolution mass spectrometry

The presence of both pharmaceuticals and pesticides in the aquatic environment has become a well-known environmental issue during the last decade. An increasing demand however still exists for sensitive and reliable monitoring tools for these rather polar contaminants in the marine environment. In recent years, the great potential of passive samplers or equilibrium based sampling techniques for evaluation of the fate of these contaminants has been shown in literature. Therefore, we developed a new analytical method for the quantification of a high number of pharmaceuticals and pesticides in passive sampling devices. The analytical procedure consisted of extraction using 1:1 methanol/acetonitrile followed by detection with ultra-high performance liquid chromatography coupled to high resolution and high mass accuracy Orbitrap mass spectrometry. Validation of the analytical method resulted in limits of quantification and recoveries ranging between 0.2 and 20 ng per sampler sheet and between 87.9 and 105.2%, respectively. Determination of the sampler-water partition coefficients of all compounds demonstrated that several pharmaceuticals and most pesticides exert a high affinity for the polydimethylsiloxane passive samplers. Finally, the developed analytical methods were used to measure the time-weighted average (TWA) concentrations of the targeted pollutants in passive samplers, deployed at eight stations in the Belgian coastal zone. Propranolol, carbamazepine and seven pesticides were found to be very abundant in the passive samplers. These obtained long-term and large-scale TWA concentrations will contribute in assessing the environmental and human health risk of these emerging pollutants.

A validated analytical method for the determination of perfluorinated compounds in surface-, sea- and sewagewater using liquid chromatography coupled to time-of-flight mass spectrometry

Perfluorinated compounds (PFCs), which are extensively used in a wide variety of applications because of their specific surfactant properties, have recently appeared as an important new class of global environmental pollutants. Quantitative analysis of PFCs in aqueous matrices remains, however, a challenging task. During this study, a new analytical method for the determination of 14 PFCs in surface-, sewage- and seawater was developed and validated. The target analytes were extracted using solid-phase extraction followed by liquid chromatography coupled to a time-of-flight mass spectrometer (LC-ToF-MS). The use of very narrow mass tolerance windows (< 10 ppm) resulted in a highly selective MS-technique for the detection of PFCs in complex aqueous matrices. Validation of this analytical method in surface-, sewage- and seawater resulted in limits of quantification (LOQs) varying from 2 to 200 ng L⁻¹, satisfying recoveries (92-134%), and good linearity (R²=0.99 for most analytes). Analysis of samples of the North Sea, the Scheldt estuary, and three harbours of the Belgian coastal region led to the detection of four different PFCs. Perfluorooctane sulfonate (PFOS) was found to be the most abundant PFC in levels up to 38.9 ng L⁻¹.

Removal of diatrizoate with catalytically active membranes incorporating microbially produced palladium nanoparticles.

There is an increasing concern about the fate of iodinated contrast media (ICM) in the environment. Limited removal efficiencies of currently applied techniques such as advanced oxidation processes require more performant strategies. The aim of this study was to establish an innovative degradation process for diatrizoate, a highly recalcitrant ICM, by using biogenic Pd nanoparticles as free suspension or immobilized in polyvinylidene fluoride (PVDF) and polysulfone (PSf) membranes. As measured by HPLC-UV, the removal of 20mg L(-1) diatrizoate by a 10mg L(-1) Pd suspension was completed after 4h at a pH of 10. LC-MS analysis provided evidence for the sequential hydrodeiodination of diatrizoate. Pd did not lose its activity after incorporation in the PVDF and PSf matrix and the highest activity (k(cat)=30.0+/-0.4h(-1) L g(-1) Pd) was obtained with a casting solution of 10% PSf and 500mg L(-1) Pd. Subsequently, water containing 20mg L(-1) diatrizoate was treated in a membrane contactor, in which the water was supplied at one side of the membrane while hydrogen was provided at the other side. In a fed batch configuration, a removal efficiency of 77% after a time period of 48h was obtained. This work showed that membrane contactors with encapsulated biogenic nanoparticles can be instrumental for treatment of water contaminated with diatrizoate.

Long-chain acylhomoserine lactones increase the anoxic ammonium oxidation rate in an OLAND biofilm.

The oxygen-limited autotrophic nitrification/denitrification (OLAND) process comprises one-stage partial nitritation and anammox, catalyzed by aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB), respectively. The goal of this study was to investigate whether quorum sensing influences anoxic ammonium oxidation in an OLAND biofilm, with AnAOB colonizing 13% of the biofilm, as determined with fluorescent in situ hybridization (FISH). At high biomass concentrations, the specific anoxic ammonium oxidation rate of the OLAND biofilm significantly increased with a factor of 1.5 ± 0.2 compared to low biomass concentrations. Supernatant obtained from the biofilm showed no ammonium-oxidizing activity on itself, but its addition to low OLAND biomass concentrations resulted in a significant activity increase of the biomass. In the biofilm supernatant, the presence of long-chain acylhomoserine lactones (AHLs) was shown using the reporter strain Chromobacterium violaceum CV026, and one specific AHL, N-dodecanoyl homoserine lactone (C12-HSL), was identified via LC-MS/MS. Furthermore, C12-HSL was detected in an AnAOB-enriched community, but not in an AerAOB-enriched community. Addition of C12-HSL to low OLAND biomass concentrations resulted in a significantly higher ammonium oxidation rate (p < 0.05). To our knowledge, this is the first report demonstrating that AHLs enhance the anoxic ammonium oxidation process. Future work should confirm which species are responsible for the in situ production of C12-HSL in AnAOB-based applications.