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Rates of methane emission from intact cores were measured during anoxic dark and oxic light and dark incubations. Rates of methane oxidation were calculated on the basis of oxic incubations by using the anoxic emissions as an estimate of... more
Rates of methane emission from intact cores were measured during anoxic dark and oxic light and dark incubations. Rates of methane oxidation were calculated on the basis of oxic incubations by using the anoxic emissions as an estimate of the maximum potential flux. This technique indicated that methane oxidation consumed up to 91% of the maximum potential flux in peat sediments but that oxidation was negligible in marl sediments. Oxygen microprofiles determined for intact cores were comparable to profiles measured in situ. Thus, the laboratory incubations appeared to provide a reasonable approximation of in situ activities. This was further supported by the agreement between measured methane fluxes and fluxes predicted on the basis of methane profiles determined by in situ sampling of pore water. Methane emissions from peat sediments, oxygen concentrations and penetration depths, and methane concentration profiles were all sensitive to light-dark shifts as determined by a combinatio...
Research Interests: Environmental Science, Chemistry, Mass Transfer, Atmospheric Chemistry, Environmental Chemistry, and 15 moreMedicine, Multidisciplinary, Aquatic Ecosystem, Peat, Fossil Fuels, Applied Environmental Microbiology, Florida Everglades, Data Collection, Methane, North America, Methane Oxidation, Chemical Reaction, Organic Matter, Energy Source, and Organic Compound
Research Interests: Chemistry, Carbon, Microbial Ecology, Biology, Activated Sludge, and 15 moreBiodiversity, Ecophysiology, Medicine, Environmental Biotechnology, Biological Sciences, Environmental Sciences, Ecosystems, Cluster Analysis, Microorganisms, Fluorescent in situ hybridization, Carbon Source, Betaproteobacteria, Microbial community, Molecular Sequence Data, and isme
Strong inhibitory effects of the anionic surfactant linear alkylbenzene sulfonate (LAS) on four strains of autotrophic ammonia-oxidizing bacteria (AOB) are reported. Two Nitrosospira strains were considerably more sensitive to LAS than... more
Strong inhibitory effects of the anionic surfactant linear alkylbenzene sulfonate (LAS) on four strains of autotrophic ammonia-oxidizing bacteria (AOB) are reported. Two Nitrosospira strains were considerably more sensitive to LAS than two Nitrosomonas strains were. Interestingly, the two Nitrosospira strains showed a weak capacity to remove LAS from the medium. This could not be attributed to adsorption or any other known physical or chemical process, suggesting that biodegradation of LAS took place. In each strain, the metabolic activity (50% effective concentration [EC 50 ], 6 to 38 mg liter −1 ) was affected much less by LAS than the growth rate and viability (EC 50 , 3 to 14 mg liter −1 ) were. However, at LAS levels that inhibited growth, metabolic activity took place only for 1 to 5 days, after which metabolic activity also ceased. The potential for adaptation to LAS exposure was investigated with Nitrosomonas europaea grown at a sublethal LAS level (10 mg liter −1 ); compare...
Research Interests: Thermodynamics, Multidisciplinary, Biological Sciences, Environmental Sciences, Applied, and 15 moreApplied Environmental Microbiology, Applied and Environmental Microbiology, CHEMICAL SCIENCES, Sewage, Growth rate, Surface Active Agents, Anionic Surfactant, Environmental Pollutants, Species Specificity, Betaproteobacteria, Ammonia oxidizing bacteria, Microbial community, Nitrosomonas, Linear Alkylbenzene Sulfonate, and Heterotrophic Bacteria
A new microarray method, the isotope array approach, for identifying microorganisms which consume a 14 C-labeled substrate within complex microbial communities was developed. Experiments were performed with a small microarray consisting... more
A new microarray method, the isotope array approach, for identifying microorganisms which consume a 14 C-labeled substrate within complex microbial communities was developed. Experiments were performed with a small microarray consisting of oligonucleotide probes targeting the 16S rRNA of ammonia-oxidizing bacteria (AOB). Total RNA was extracted from a pure culture of Nitrosomonas eutropha grown in the presence of [ 14 C]bicarbonate. After fluorescence labeling of the RNA and microarray hybridization, scanning of all probe spots for fluorescence and radioactivity revealed that specific signals were obtained and that the incorporation of 14 C into rRNA could be detected unambiguously. Subsequently, we were able to demonstrate the suitability of the isotope array approach for monitoring community composition and CO 2 fixation activity of AOB in two nitrifying activated-sludge samples which were incubated with [ 14 C]bicarbonate for up to 26 h. AOB community structure in the activated-s...
Research Interests: Biology, Activated Sludge, Medicine, Multidisciplinary, Applied, and 15 moreApplied Environmental Microbiology, Oxidoreductases, Bacteria, Ammonia, Ecosystem, Fluorescent in situ hybridization, Sewage, Autoradiography, Community Composition, Microbial Community Structure, Ammonia oxidizing bacteria, Microbial community, Nitrosomonas, Molecular Sequence Data, and Bicarbonates
The active herbicide ingredient glyphosate [N-(phosphonomethyl)glycine] is frequently detected as a contaminant in groundwater and surface waters. This study investigated effects of UV-A (365 nm), UV-B (302 nm) and UV-C (254 nm)... more
The active herbicide ingredient glyphosate [N-(phosphonomethyl)glycine] is frequently detected as a contaminant in groundwater and surface waters. This study investigated effects of UV-A (365 nm), UV-B (302 nm) and UV-C (254 nm) irradiation of glyphosate in water on photolysis and toxicity to aquatic organisms from different trophic levels. A test battery with bacteria (Bacillus subtilis, Aliivibrio fischeri), a green microalga (Raphidocelis subcapitata), and a crustacean (Daphnia magna) was used to assess biological effect of glyphosate and bioactive transformation products before and after UV irradiation (4.7–70 J/cm2). UV-C irradiation at 20 J/cm2 resulted in a 2–23-fold decrease in toxicity of glyphosate to aquatic test organisms. UV-B irradiation at 70 J/cm2 caused a twofold decrease whereas UV-A did not affect glyphosate toxicity at doses ≤ 70 J/cm2. UV-C irradiation of glyphosate in drinking water and groundwater with naturally occurring organic and inorganic constituents sho...
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Manganese removal in drinking water biofilters is facilitated by biological and physico-chemical processes, but knowledge regarding the relative role of these mechanisms during start-up is very limited. The aim of this study was to... more
Manganese removal in drinking water biofilters is facilitated by biological and physico-chemical processes, but knowledge regarding the relative role of these mechanisms during start-up is very limited. The aim of this study was to identify the dominant process for manganese removal occurring during the start-up period of sand filters with and without inoculation by addition of matured sand collected from an operating groundwater-based waterworks. Inoculation with matured filter sand is frequently used to accelerate the start-up in virgin biofilters and to rapidly obtain compliant water quality. The non-inoculated filter took 41 days to comply with manganese quality criteria, whereas the inoculated filter with 20% matured sand showed removal from Day 1 and compliance from Day 25. By Day 48, the inoculated filter showed two times higher manganese removal rates and manganese oxides deposits. Using sodium azide as an inhibitor of microbial activity, it was found that manganese removal ...
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Manganese removal is a typical concern in drinking water production. Biofiltration may be used when treating groundwater sources but the onset of manganese removal in virgin biofilters can vary considerably. The aim of this study was to... more
Manganese removal is a typical concern in drinking water production. Biofiltration may be used when treating groundwater sources but the onset of manganese removal in virgin biofilters can vary considerably. The aim of this study was to investigate the effect of different filter media on manganese oxidation and bacterial diversity in biofilters during the start-up. The onset of manganese oxidation in four virgin granular filter media (quartz, calcium carbonate, polystyrene, andmanganese oxide) and one matured medium (quartz) was followed during the start-up. Immediate manganese removal was achieved by manganese oxide, while 48, 57 and 72 days were required by virgin quartz, calcium carbonate and polystyrene, respectively. The bacterial community was investigated using DAPI staining, quantitative polymerase chain reaction (qPCR), 16S rRNA gene pyrosequencing, and bacterial enrichments. Bacterial abundance was greatest on polystyrene and matured quartz. Molecular community analysis and bacterial enrichments suggested the presence ofmanganese oxidizing bacteria on all media coatings after the start-up period. Virgin quartz and calcium carbonate showed similar bacterial communities whereas manganese oxide and polystyrene were distinct. This investigation suggests that when inoculating different filter media with an identical water source, the bacterial diversity andonset ofmanganese oxidationduring start-up is strongly influencedby the filtermedia type. doi: 10.2166/aqua.2017.084 s://iwaponline.com/aqua/article-pdf/66/8/641/223213/jws0660641.pdf I. L. Breda (corresponding author) P. Roslev Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark E-mail: ilb@bio.aau.dk I. L. Breda Group of Project and Development, Skanderborg Forsyningsvirksomhed A/S, Døjsøvej 1, 8660 Skanderborg, Denmark L. Ramsay Research Group for Energy and Environment, VIA University College, Chr. M. Østergaards Vej 4, 8700 Horsens, Denmark
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Land slugs are occasionally observed as contaminants in groundwater wells and drinking water treatment plants including storage tanks. Slugs may feed on carrion and feces, and they are potential vectors of pathogens such as Listeria... more
Land slugs are occasionally observed as contaminants in groundwater wells and drinking water treatment plants including storage tanks. Slugs may feed on carrion and feces, and they are potential vectors of pathogens such as Listeria monocytogenes. We isolated L. monocytogenes from the pest slug Arion vulgaris and examined the persistence and survival of human- and slug-derived L. monocytogenes in groundwater-based drinking water and biofilms. L. monocytogenes survival was evaluated using cultivation and cultivation-independent techniques. L. monocytogenes remained culturable for 35–47 days in drinking water with first-order decay rates between 0.314 and 0.457 h−1 (T99 ≥10 days). Attachment of L. monocytogenes to filter sand delayed washout from drinking water filters and increased persistence 2–3-fold. Indigenous biofilms stimulated initial surface attachment 10–100-fold but L. monocytogenes declined more rapidly in drinking water biofilms compared with virgin filters not colonized ...
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Glyphosate (N-(phosphonomethyl)glycine) is the active ingredient in a range of popular broad-spectrum herbicide formulations. Glyphosate is a chelating agent that can form stable complexes with divalent metal ions including Cu(II). Little... more
Glyphosate (N-(phosphonomethyl)glycine) is the active ingredient in a range of popular broad-spectrum herbicide formulations. Glyphosate is a chelating agent that can form stable complexes with divalent metal ions including Cu(II). Little is known about the bioavailability and ecotoxicity of glyphosate-Cu(II) complexes to aquatic organisms. In this study, we used video tracking and behavior analysis to investigate sublethal effects of binary mixtures of glyphosate and Cu(II) to juvenile D. magna. Behavioral responses were quantified for individual D. magna after 24h and 48h exposure to glyphosate and glyhosate-Cu(II) mixtures. Sublethal concentrations resulted in decreases in swimming velocity, acceleration speed, and distance moved whereas inactive time of D. magna increased. Distance moved and inactive time were the most responsive parameters to glyphosate and glyphosate-Cu(II) exposure. On a molar basis, glyphosate-Cu(II) complexes appeared more toxic to D. magna than glyphosate alone. The 48h EC50 for glyphosate and glyphosate-Cu(II) determined from swimming distance were 75.2μM and 8.4μM, respectively. In comparison, traditional visual observation of mobility resulted in 48h EC50 values of 52.8μM and 25.5μM for glyphosate and glyphosate-Cu(II), respectively. The behavioral responses indicated that exposure of D. magna to mixtures of glyphosate and Cu(II) attenuated acute metal toxicity but increased apparent glyphosate toxicity due to complexation with Cu(II). The study suggests that glyphosate is a likely mediator of aquatic metal toxicity, and that video tracking provides an opportunity for quantitative studies of sublethal effects of pesticide complexes.
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Aquatic pollutants are often biologically active at low concentrations and impact on biota in combination with other abiotic stressors. Traditional toxicity tests may not detect these effects, and there is a need for sensitive... more
Aquatic pollutants are often biologically active at low concentrations and impact on biota in combination with other abiotic stressors. Traditional toxicity tests may not detect these effects, and there is a need for sensitive high-throughput methods for detecting sublethal effects. We have evaluated an automated infra-red (IR) light-based monitor for recording the swimming activity of Daphnia magna to establish temporal patterns of toxicant effects on an individual level. Activity was recorded for 48 h and the sensitivity of the monitor was evaluated by exposing D. magna to the reference chemicals K2 Cr2 O7 at 15, 20 and 25 °C and 2,4-dichlorophenol at 20 °C. Significant effects (P < 0.001) of toxicant concentrations, exposure time and incubation temperatures were observed. At 15 °C, the swimming activity remained unchanged for 48 h at sublethal concentrations of K2 Cr2 O7 whereas activity at 20 and 25 °C was more biphasic with decreases in activity occurring after 12-18 h. A si...
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Daphnia magna is a widely used model organism for aquatic toxicity testing. In the present study, we investigated the hydrolytic enzyme activity of D. magna after exposure to toxicant stress. In vivo enzyme activity was quantified using... more
Daphnia magna is a widely used model organism for aquatic toxicity testing. In the present study, we investigated the hydrolytic enzyme activity of D. magna after exposure to toxicant stress. In vivo enzyme activity was quantified using 15 fluorogenic enzyme probes based on 4-methylumbelliferyl or 7-amino-4-methylcoumarin. Probing D. magna enzyme activity was evaluated using short-term exposure (24-48 h) to the reference chemical K2 Cr2 O7 , or the herbicide formulation Roundup®. Toxicant induced changes in hydrolytic enzyme activity were compared to changes in mobility (ISO 6341). The results showed that hydrolytic enzyme activity was quantifiable as a combination of whole body fluorescence of D. magna, and fluorescence of the surrounding water. Exposure of D. magna to lethal and sublethal concentrations of Roundup® resulted in loss of whole body enzyme activity, and release of cell constituents including enzymes and DNA. Roundup® caused comparable inhibition of mobility and alkali...
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The inhibitory effects of the fuel additive methyl tert-butyl ether (MTBE) and potential degradation products tert-butanol (TBA) and formaldehyde was examined using mixed microbial biomass, and six strains of bioluminescent bacteria and... more
The inhibitory effects of the fuel additive methyl tert-butyl ether (MTBE) and potential degradation products tert-butanol (TBA) and formaldehyde was examined using mixed microbial biomass, and six strains of bioluminescent bacteria and yeast. The purpose was to assess microbial toxicity with quantitative bioluminescent and fluorescent endpoints, and to identify sensitive proxies suitable for monitoring MTBE contamination. Bioluminescent Aliivibrio fischeri DSM 7151 (formerly Vibrio fischeri) appeared highly sensitive to MTBE exposure, and was a superior test organisms compared to lux-tagged Escherichia coli DH5α, Pseudomonas fluorescens DF57-40E7 and Saccharomyces cerevisiae BLYR. EC10 and EC50 for acute MTBE toxicity in A. fischeri were 1.1 and 10.9 mg L(-1), respectively. Long term (24h) MTBE exposure resulted in EC10 values of 0.01 mg L(-1). TBA was significantly less toxic with EC10 and EC50 for acute and chronic toxicity >1000 mg L(-1). Inhibition of bioluminescence was gen...
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The metabolism of atmospheric methane in a forest soil was studied by radiotracer techniques. Maximum (sup14)CH(inf4) oxidation (163.5 pmol of C cm(sup-3) h(sup-1)) and (sup14)C assimilation (50.3 pmol of C cm(sup-3) h(sup-1)) occurred at... more
The metabolism of atmospheric methane in a forest soil was studied by radiotracer techniques. Maximum (sup14)CH(inf4) oxidation (163.5 pmol of C cm(sup-3) h(sup-1)) and (sup14)C assimilation (50.3 pmol of C cm(sup-3) h(sup-1)) occurred at the A(inf2) horizon located 15 to 18 cm below the soil surface. At this depth, 31 to 43% of the atmospheric methane oxidized was assimilated into microbial biomass; the remaining methane was recovered as (sup14)CO(inf2). Methane-derived carbon was incorporated into all major cell macromolecules by the soil microorganisms (50% as proteins, 19% as nucleic acids and polysaccharides, and 5% as lipids). The percentage of methane assimilated (carbon conversion efficiency) remained constant at temperatures between 5 and 20(deg)C, followed by a decrease at 30(deg)C. The carbon conversion efficiency did not increase at methane concentrations between 1.7 and 1,000 ppm. In contrast, the overall methane oxidation activity increased at elevated methane concentr...
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The capacity for anaerobic metabolism of endogenous and selected exogenous substrates in carbon- and energy-starved methanotrophic bacteria was examined. The methanotrophic isolate strain WP 12 survived extended starvation under anoxic... more
The capacity for anaerobic metabolism of endogenous and selected exogenous substrates in carbon- and energy-starved methanotrophic bacteria was examined. The methanotrophic isolate strain WP 12 survived extended starvation under anoxic conditions while metabolizing 10-fold less endogenous substrate than did parallel cultures starved under oxic conditions. During aerobic starvation, the cell biomass decreased by 25% and protein and lipids were the preferred endogenous substrates. Aerobic protein degradation (24% of total protein) took place almost exclusively during the initial 24 h of starvation. Metabolized carbon was recovered mainly as CO(inf2) during aerobic starvation. In contrast, cell biomass decreased by only 2.4% during anaerobic starvation, and metabolized carbon was recovered mainly as organic solutes in the starvation medium. During anaerobic starvation, only the concentration of intracellular low-molecular-weight compounds decreased, whereas no significant changes were ...
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The effects of carbon deprivation on survival of methanotrophic bacteria were compared in cultures incubated in the presence and absence of oxygen in the starvation medium. Survival and recovery of the examined methanotrophs were... more
The effects of carbon deprivation on survival of methanotrophic bacteria were compared in cultures incubated in the presence and absence of oxygen in the starvation medium. Survival and recovery of the examined methanotrophs were generally highest for cultures starved under anoxic conditions as indicated by poststarvation measurements of methane oxidation, tetrazolium salt reduction, plate counts, and protein synthesis. Methylosinus trichosporium OB3b survived up to 6 weeks of carbon deprivation under anoxic conditions while maintaining a physiological state that allowed relatively rapid (hours) methane oxidation after substrate addition. A small fraction of cells starved under oxic and anoxic conditions (4 and 10%, respectively) survived more than 10 weeks but required several days for recovery on plates and in liquid medium. A non-spore-forming methanotroph, strain WP 12, displayed 36 to 118% of its initial methane oxidation capacity after 5 days of carbon deprivation. Oxidation r...
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The tetrazolium salt sodium 3'-{1-[(phenylamino)-carbonyl]-3,4-tetrazolium}-bis (4-methoxy-6-nitro)benzene-sulfonic acid hydrate (XTT) was examined for use as a colorimetric indicator of viability in respiring bacteria. XTT was... more
The tetrazolium salt sodium 3'-{1-[(phenylamino)-carbonyl]-3,4-tetrazolium}-bis (4-methoxy-6-nitro)benzene-sulfonic acid hydrate (XTT) was examined for use as a colorimetric indicator of viability in respiring bacteria. XTT was reduced to an orange, water-soluble formazan product by Methylosinus trichosporium OB3b, Pseudomonas putida, Escherichia coli, and Bacillus subtilis. Formazan production was proportional to live cell biomass, and XTT was reduced by all cultures in the absence of added electron-coupling agents. XTT reduction by M. trichosporium OB3b was linear over several hours and was stimulated by the presence of an exogenous substrate (methanol). Addition of cyanide to cultures incubated under oxic conditions gave an initial 10-fold increase in XTT reduction. Viability of bacteria incubated in the absence of exogenous carbon substrates was measured as XTT reduction and compared with viability estimates from plate counts. Results obtained with the two methods were gener...
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Methane is involved in a number of chemical and physical processes in the Earth's atmosphere, including global warming. Atmospheric methane originates mainly from biogenic sources, such as rice paddies and natural wetlands; the former... more
Methane is involved in a number of chemical and physical processes in the Earth's atmosphere, including global warming. Atmospheric methane originates mainly from biogenic sources, such as rice paddies and natural wetlands; the former account for at least 30% of the global annual emission of methane to the atmosphere. As an increase of rice production by 60% is the most appropriate way to sustain the estimated increase of the human population during the next three decades, intensified global fertilizer application will be necessary: but it is known that an increase of the commonly used ammonium-based fertilizers can enhance methane emission from rice agriculture. Approximately 10-30% of the methane produced by methanogens in rice paddies is consumed by methane-oxidizing bacteria associated with the roots of rice; these bacteria are generally thought to be inhibited by ammonium-based fertilizers, as was demonstrated for soils and sediments. In contrast, we show here that the acti...
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Microorganisms that oxidize atmospheric methane in soils were characterized by radioactive labelling with (14)CH(4) followed by analysis of radiolabelled phospholipid ester-linked fatty acids ((14)C-PLFAs). The radioactive fingerprinting... more
Microorganisms that oxidize atmospheric methane in soils were characterized by radioactive labelling with (14)CH(4) followed by analysis of radiolabelled phospholipid ester-linked fatty acids ((14)C-PLFAs). The radioactive fingerprinting technique was used to compare active methanotrophs in soil samples from Greenland, Denmark, the United States, and Brazil. The (14)C-PLFA fingerprints indicated that closely related methanotrophic bacteria were responsible for the oxidation of atmospheric methane in the soils. Significant amounts of labelled PLFAs produced by the unknown soil methanotrophs coeluted with a group of fatty acids that included i17:0, a17:0, and 17:1omega8c (up to 9.0% of the total (14)C-PLFAs). These PLFAs are not known to be significant constituents of methanotrophic bacteria. The major PLFAs of the soil methanotrophs (73.5 to 89.0% of the total PLFAs) coeluted with 18:1 and 18:0 fatty acids (e.g., 18:1omega9, 18:1omega7, and 18:0). The (14)C-PLFAs fingerprints of the ...
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The metabolism of phthalic acid (PA) and di-(2-ethylhexyl)phthalate (DEHP) in sludge-amended agricultural soil was studied with radiotracer techniques. The initial rates of metabolism of PA and DEHP (4.1 nmol/g [dry weight]) were... more
The metabolism of phthalic acid (PA) and di-(2-ethylhexyl)phthalate (DEHP) in sludge-amended agricultural soil was studied with radiotracer techniques. The initial rates of metabolism of PA and DEHP (4.1 nmol/g [dry weight]) were estimated to be 731.8 and 25.6 pmol/g (dry weight) per day, respectively. Indigenous microorganisms assimilated 28 and 17% of the carbon in [14C]PA and [14C]DEHP, respectively, into microbial biomass. The rates of DEHP metabolism were much greater in sludge assays without soil than in assays with sludge-amended soil. Mineralization of [14C]DEHP to 14CO2 increased fourfold after inoculation of sludge and soil samples with DEHP-degrading strain SDE 2. The elevated mineralization potential was maintained for more than 27 days. Experiments performed with strain SDE 2 suggested that the bioavailability and mineralization of DEHP decreased substantially in the presence of soil and sludge components. The microorganisms metabolizing PA and DEHP in sludge and sludge...
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ABSTRACT Effluent from the secondary treatment of municipal wastewater was further treated with membrane filtration to reduce its toxicity. Five different inorganic membranes were tested, namely, an α-alumina microfiltration membrane, an... more
ABSTRACT Effluent from the secondary treatment of municipal wastewater was further treated with membrane filtration to reduce its toxicity. Five different inorganic membranes were tested, namely, an α-alumina microfiltration membrane, an anatase titania ultrafiltration membrane, an γ-alumina nanofiltration membrane, an amorphous titania nanofiltration membrane, and an amorphous hybrid organo-silica membrane. The permeabilities and selectivities (color, UV254-absorbing components, conductivity and inorganic nitrogen compounds) of the membranes were determined, and the γ-alumina nanofiltration membrane was found to be the most promising membrane for the treatment of the effluent. The effluent flux was measured to be approximately 40 L m-2 h-1 for the γ-alumina nanofiltration membrane, and it removed nearly 75% of the UV254-absorbing components and 15% of the ions. It also removed 40% of the CuCl and 25% of the CuSO4 from the spiked effluent. The fouling resistance was less pronounced for the γ-alumina membrane compared with the other tested NF membranes. The removal of fecal indicator bacteria was determined by measuring the amounts of E. coli and Enterococci, and the removal of toxic compounds was investigated in bioassays with Daphnia magna and Aliivibrio fischeri. The γ-alumina nanofiltration membrane reduced the wastewater concentration of E. coli (97.3%) and Enterococci (98.4%), and the bioassays demonstrated that filtration with the γ-alumina nanofiltration membrane reduced the overall toxicity of the effluent.
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Traditional cultivation-dependent tests for coliform bacteria in food and drinking water take 18–24 h to complete. Bioluminescence-based enzyme assays can potentially reduce analysis time for indicator bacteria such as coliforms. In the... more
Traditional cultivation-dependent tests for coliform bacteria in food and drinking water take 18–24 h to complete. Bioluminescence-based enzyme assays can potentially reduce analysis time for indicator bacteria such as coliforms. In the present study, we developed a simple presence/absence (P/A) bioluminescence procedure for rapid detection of coliform bacteria in groundwater-based drinking water. The bioluminescence procedure targeting β-d-galactosidase activity in coliform bacteria
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Sources of faecal pollution in coastal recreational waters may be identified by analysing different host associated microorganisms or molecular markers. However, the microbial targets are often present at low numbers in moderately... more
Sources of faecal pollution in coastal recreational waters may be identified by analysing different host associated microorganisms or molecular markers. However, the microbial targets are often present at low numbers in moderately impacted waters, and often exhibit significant temporal and spatial variability in waters with fluctuating faecal loads. This patchy occurrence can limit successful detection of relevant targets in microbial source tracking studies. In this study, we explored the possibility for using the blue mussel (Mytilus edulis) as a biosampler for accumulation of faecal bacteria relevant for microbial source tracking. Non-contaminated blue mussels were transferred to three coastal recreational waters affected by faecal pollution of unknown origin. Molecular markers associated with animal and human waste were targeted by PCR and compared in seawater and mussel samples. The results demonstrated that transplanted mussels in simple enclosures accumulated and retained ele...
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... of California, Davis, CA 95616 ... Two Danish agricultural soils were used in this study: Lerbjerg 5 sandy clay (f oc ∼0.013, 38% clay), retrieved at Lerbjerg, Denmark (56°22′N, 9°59′E), andLundgaard sand (f oc ∼0.014, 5% clay) from... more
... of California, Davis, CA 95616 ... Two Danish agricultural soils were used in this study: Lerbjerg 5 sandy clay (f oc ∼0.013, 38% clay), retrieved at Lerbjerg, Denmark (56°22′N, 9°59′E), andLundgaard sand (f oc ∼0.014, 5% clay) from Lundgaard, Denmark (55°27′N; 9°10′E ...
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ABSTRACT Oxidation of atmospheric methane by soil methanotrophs is a microbial process highly susceptible to physical and chemical disturbances. In this study, atmospheric methane oxidation activity in soil samples from beech (Fagus... more
ABSTRACT Oxidation of atmospheric methane by soil methanotrophs is a microbial process highly susceptible to physical and chemical disturbances. In this study, atmospheric methane oxidation activity in soil samples from beech (Fagus sylvatica) and spruce (Picea abies) forest stands decreased significantly after physical disturbance and/or increased exposure to ambient air. This activity loss was oxygen dependent, but independent of the presence of atmospheric methane. However, methanotrophic activity in forest soil was stabilized by amendment with various sorbents including activated charcoal, aminopropylsilane, and gamma aluminum oxide (γ-Al2O3). γ-AlO3 at a concentration &gt;1% (g g−1) was found to stabilize and sometimes stimulate oxidation of atmospheric methane in soil from both beech and spruce forest stands. γ-Al2O3 amendment also stimulated atmospheric methane oxidation in advective flow-based soil biofilters, and the filter efficiency was found to increase with time. In both soil samples and soil biofilters, elevated oxidation of atmospheric methane was sustained for &gt;100 days. γ-Al2O3 likely immobilized potentially inhibitory soil constituents including inorganic nitrogen and soil organics. The results of the study indicated that: 1) decreases in atmospheric methane oxidation activity in topsoil after soil homogenization and/or increased air exposure was likely related to increased bioavailability of inhibitory substances; 2) indigenous inhibitory compounds are present in topsoil in both beech and spruce forest soil; and 3) oxidation of atmospheric methane in soil can be restored and sometimes stimulated by immobilizing inhibitory compounds using γ-Al2O3 as sorbent.