| 1. |
- Broman, Elias, 1985-, et al.
(författare)
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Low temperature, autotrophic microbial denitrification using thiosulfate or thiocyanate as electron donor
- 2017
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Ingår i: Biodegradation. - : Springer. - 0923-9820 .- 1572-9729. ; 28:4, s. 287-301
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Tidskriftsartikel (refereegranskat)abstract
- Wastewaters generated during mining and processing of metal sulfide ores are often acidic (pH < 3) and can contain significant concentrations of nitrate, nitrite, and ammonium from nitrogen based explosives. In addition, wastewaters from sulfide ore treatment plants and tailings ponds typically contain large amounts of inorganic sulfur compounds, such as thiosulfate and tetrathionate. Release of these wastewaters can lead to environmental acidification as well as an increase in nutrients (eutrophication) and compounds that are potentially toxic to humans and animals. Waters from cyanidation plants for gold extraction will often conjointly include toxic, sulfur containing thiocyanate. More stringent regulatory limits on the release of mining wastes containing compounds such as inorganic sulfur compounds, nitrate, and thiocyanate, along the need to increase production from sulfide mineral mining calls for low cost techniques to remove these pollutants under ambient temperatures (approximately 8 °C). In this study, we used both aerobic and anaerobic continuous cultures to successfully couple inorganic sulfur compound (i.e. thiosulfate and thiocyanate) oxidation for the removal of nitrogenous compounds under neutral to acidic pH at the low temperatures typical for boreal climates. Furthermore, the development of the respective microbial communities was identified over time by DNA sequencing, and found to contain a consortium including populations aligning within Flavobacterium, Thiobacillus, and Comamonadaceae lineages. This is the first study to remediate mining waste waters by coupling autotrophic thiocyanate oxidation to nitrate reduction at low temperatures and acidic pH by means of an identified microbial community.
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| 2. |
- Chusova, Olga, et al.
(författare)
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Biotransformation of pink water TNT on the surface of a low-cost adsorbent pine bark
- 2015
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 26:5, s. 375-386
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Tidskriftsartikel (refereegranskat)abstract
- This two-week anaerobic batch study evaluated 2,4,6-trinitrotoluene (TNT) removal efficiency from industrial pink water by (1) adsorption on low-cost adsorbent pine bark, and (2) adsorption coupled with TNT biotransformation by specialised microbial communities. Samples of the supernatant and acetonitrile extracts of pine bark were analysed by HPLC, while the composition of the bacterial community of the experimental batches, inocula and pine bark were profiled by high-throughput sequencing the V6 region of the bacterial 16S rRNA gene. Integrated adsorption and biotransformation proved to be the most efficient method for TNT removal from pink water. The type of applied inoculum had a profound effect on TNT removal efficiencies and microbial community structures, which were dominated by phylotypes belonging to the Enterobacteriaceae family. The analysis of acetonitrile extracts of pine bark supported the hypothesis that the microbial community indigenous to pine bark has the ability to degrade TNT.
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| 3. |
- Eriksson, Sara, 1974, et al.
(författare)
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Propylphenols are metabolites in the anaerobic biodegradation of propylbenzene under iron-reducing conditions
- 2005
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 1572-9729 .- 0923-9820. ; 16:3, s. 253-263
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Tidskriftsartikel (refereegranskat)abstract
- The metabolism of monoaromatic hydrocarbons by an iron-reducing bacterial enrichment culture originating from diesel-contaminated groundwater was examined using d 7 -propylbenzene as a model hydrocarbon. Sequence analysis of the 16S rDNA gene showed that the dominant part (10 of 10 clones) of the enrichment culture consisted of a bacterium closely related to clones found in benzene-contaminated groundwater and to the iron-reducing β- proteobacterium, Rhodoferax ferrireducens (similarity values were 99.5% and 98.3%, respectively). In degradation studies conducted over 18 weeks, d 7 -propylphenols were detected by gas chromatography-mass spectrometry (GC/MS) as intra-cellular metabolites concomitant with cell growth in the cultures. The amount of propylphenols increased during the exponential growth phase, and by the end of this phase 4 × 10 -14 moles of ferric iron were reduced and 3 × 10 -15 moles propylphenol produced for every cell formed. During the stationary growth phase the cell density was approximately 10 7 ml -1 , with significantly correlated amounts of propylphenols. Succinate derivates of propylbenzene or phenylpropanol previously shown to be the initial metabolites in the anaerobic degradation of alkylbenzenes could not be identified. This study is the first to report that oxidation of propylbenzene to propylphenols can initiate anaerobic propylbenzene degradation and that iron-reducing bacteria are responsible for this process. In addition, the study shows the importance of taking account of the metabolites adhering to solid phases when determining the extent of biodegradation, so as not to underestimate the extent of the process.
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| 4. |
- Hultberg, Malin, et al.
(författare)
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Effects of fungal-assisted algal harvesting through biopellet formation on pesticides in water
- 2018
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 29, s. 557-565
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Tidskriftsartikel (refereegranskat)abstract
- Recent research has demonstrated the potential of using filamentous fungi to form pellets with microalgae (biopellets), in order to facilitate harvesting of microalgae from water following algae-based treatment of wastewater. In parallel, there is a need to develop techniques for removing organic pollutants such as pesticides and pharmaceuticals from wastewater. In experiments using the microalga Chlorella vulgaris, the filamentous fungus Aspergillus niger and biopellets composed of these microorganisms, this study investigated whether fungal-assisted algal harvesting can also remove pesticides from contaminated water. A mixture of 38 pesticides was tested and the concentrations of 17 of these were found to be reduced significantly in the biopellet treatment, compared with the control. After harvesting, the concentration of total pesticides in the algal treatment did not differ significantly from that in the control. However, in the fungal treatment and biopellet treatment, the concentration was significantly lower (59.6 +/- 2.0 mu g/L and 56.1 +/- 2.8 mu g/L, respectively) than in the control (66.6 +/- 1.0 mu g/L). Thus fungal-assisted algal harvesting through biopellet formation can also provide scope for removing organic pollutants from wastewater, with removal mainly being performed by the fungus.
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| 5. |
- Monard, Cécile
(författare)
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Estimating the biodegradation of pesticide in soils by monitoring pesticide-degrading gene expression
- 2013
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 24, s. 203-213
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Tidskriftsartikel (refereegranskat)abstract
- Assessing in situ microbial abilities of soils to degrade pesticides is of great interest giving insight in soil filtering capability, which is a key ecosystem function limiting pollution of groundwater. Quantification of pesticide-degrading gene expression by reverse transcription quantitative PCR (RT-qPCR) was tested as a suitable indicator to monitor pesticide biodegradation performances in soil. RNA extraction protocol was optimized to enhance the yield and quality of RNA recovered from soil samples to perform RT-qPCR assays. As a model, the activity of atrazine-degrading communities was monitored using RT-qPCRs to estimate the level of expression of atzD in five agricultural soils showing different atrazine mineralization abilities. Interestingly, the relative abundance of atzD mRNA copy numbers was positively correlated to the maximum rate and to the maximal amount of atrazine mineralized. Our findings indicate that the quantification of pesticide-degrading gene expression may be suitable to assess biodegradation performance in soil and monitor natural attenuation of pesticide.
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| 6. |
- Palmroth, Marja, et al.
(författare)
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Effect of modified Fenton's reaction on microbial activity and removal of PAHs in creosote oil contaminated soil
- 2006
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 17:2, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the removal of polycyclic aromatic hydrocarbons (PAHs) from creosote oil contaminated soil by modified Fenton's reaction in laboratory-scale column experiments and subsequent aerobic biodegradation of PAHs by indigenous bacteria during incubation of the soil. The effect of hydrogen peroxide addition for 4 and 10 days and saturation of soil with H2O2 on was studied. In both experiments the H2O2 dosage was 0.4 g H2O2/g soil. In completely H2O2-saturated soil the removal of PAHs (44% within 4 days) by modified Fenton reaction was uniform over the entire soil column. In non-uniformly saturated soil, PAH removal was higher in completely saturated soil (52% in 10 days) compared to partially saturated soil, with only 25% in 10 days. The effect of the modified Fenton's reaction on the microbial activity in the soil was assessed based on toxicity tests towards Vibrio fischeri, enumeration of viable and dead cells, microbial extracellular enzyme activity, and oxygen consumption and carbon dioxide production during soil incubation. During the laboratory-scale column experiments, the toxicity of column leachate towards Vibrio fischeri increased as a result of the modified Fenton's reaction. The activities of the microbial extracellular enzymes acetate- and acidic phosphomono-esterase were lower in the incubated modified Fenton's treated soil compared to extracellular enzyme activities in untreated soil. Abundance of viable cells was lower in incubated modified Fenton treated soil than in untreated soil. Incubation of soil in serum bottles at 20 degrees C resulted in consumption of oxygen and formation of carbon dioxide, indicating aerobic biodegradation of organic compounds. In untreated soil 20-30% of the PAHs were biodegraded during 2 months of incubation. Incubation of chemically treated soil slightly increased PAH-removal compared to PAH-removal in untreated soil.
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| 7. |
- Pizzul, Leticia, et al.
(författare)
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Degradation of glyphosate and other pesticides by ligninolytic enzymes
- 2009
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 20, s. 751-759
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Tidskriftsartikel (refereegranskat)abstract
- The ability of pure manganese peroxidase (MnP), laccase, lignin peroxidase (LiP) and horseradish peroxidase (HRP) to degrade the widely used herbicide glyphosate and other pesticides was studied in separate in vitro assays with addition of different mediators. Complete degradation of glyphosate was obtained with MnP, MnSO(4) and Tween 80, with or without H(2)O(2). In the presence of MnSO(4), with or without H(2)O(2), MnP also transformed the herbicide, but to a lower rate. Laccase degraded glyphosate in the presence of (a) 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), (b) MnSO(4) and Tween 80 and (c) ABTS, MnSO(4) and Tween 80. The metabolite AMPA was detected in all cases where degradation of glyphosate occurred and was not degraded. The LiP was tested alone or with MnSO(4), Tween 80, veratryl alcohol or H(2)O(2) and in the HRP assay the enzyme was added alone or with H(2)O(2) in the reaction mixture. However, these enzymes did not degrade glyphosate. Further experiments using MnP together with MnSO(4) and Tween 80 showed that the enzyme was also able to degrade glyphosate in its commercial formulation Roundup(A (R)) Bio. The same enzyme mixture was tested for degradation of 22 other pesticides and degradation products present in a mixture and all the compounds were transformed, with degradation percentages ranging between 20 and 100%. Our results highlight the potential of ligninolytic enzymes to degrade pesticides. Moreover, they suggest that the formation of AMPA, the main metabolite of glyphosate degradation found in soils, can be a result of the activity of lignin-degrading enzymes.
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| 8. |
- Powlowski, J, et al.
(författare)
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Genetics and biochemistry of phenol degradation by Pseudomonas sp. CF600.
- 1994
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Ingår i: Biodegradation. - 0923-9820 .- 1572-9729. ; 5:3-4
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Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas sp. strain CF600 is an efficient degrader of phenol and methylsubstituted phenols. These compounds are degraded by the set of enzymes encoded by the plasmid located dmpoperon. The sequences of all the fifteen structural genes required to encode the nine enzymes of the catabolic pathway have been determined and the corresponding proteins have been purified. In this review the interplay between the genetic analysis and biochemical characterisation of the catabolic pathway is emphasised. The first step in the pathway, the conversion of phenol to catechol, is catalysed by a novel multicomponent phenol hydroxylase. Here we summarise similarities of this enzyme with other multicomponent oxygenases, particularly methane monooxygenase (EC 1.14.13.25). The other enzymes encoded by the operon are those of the well-known meta-cleavage pathway for catechol, and include the recently discovered meta-pathway enzyme aldehyde dehydrogenase (acylating) (EC 1.2.1.10). The known properties of these meta-pathway enzymes, and isofunctional enzymes from other aromatic degraders, are summarised. Analysis of the sequences of the pathway proteins, many of which are unique to the meta-pathway, suggests new approaches to the study of these generally little-characterised enzymes. Furthermore, biochemical studies of some of these enzymes suggest that physical associations between meta-pathway enzymes play an important role. In addition to the pathway enzymes, the specific regulator of phenol catabolism, DmpR, and its relationship to the XylR regulator of toluene and xylene catabolism is discussed.
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| 9. |
- Rodriguez-Gomez, Raúl, et al.
(författare)
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A model to describe the performance of the UASB reactor
- 2014
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 25:2, s. 239-251
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Tidskriftsartikel (refereegranskat)abstract
- A dynamic model to describe the performance of the Upflow Anaerobic Sludge Blanket (UASB) reactor was developed. It includes dispersion, advection, and reaction terms, as well as the resistances through which the substrate passes before its biotransformation. The UASB reactor is viewed as several continuous stirred tank reactors connected in series. The good agreement between experimental and simulated results shows that the model is able to predict the performance of the UASB reactor (i.e. substrate concentration, biomass concentration, granule size, and height of the sludge bed).
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| 10. |
- Shrivastava, Nidhi, et al.
(författare)
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Important amino acid residues of hexachlorocyclohexane dehydrochlorinases (LinA) for enantioselective transformation of hexachlorocyclohexane isomers
- 2017
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Ingår i: Biodegradation. - : SPRINGER. - 0923-9820 .- 1572-9729. ; 28:2-3, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- LinA-type1 and LinA-type2 are two well-characterized variants of the enzyme hexachlorocyclohexane (HCH)-dehydrochlorinase. They differ from each other at ten amino acid positions and exhibit differing enantioselectivity for the transformation of the (-) and (+) enantiomers of alpha-HCH. Amino acids responsible for this enantioselectivity, however, are not known. An in silico docking analysis identified four amino acids (K20, L96, A131, and T133) in LinA-type1 that could be involved in selective binding of the substrates. Experimental studies with constructed mutant enzymes revealed that a combined presence of three amino acid changes in LinA-type1, i.e. K20Q, L96C, and A131G, caused a reversal in its preference from the (-) to the (+) enantiomer of alpha-HCH. This preference was enhanced by the additional amino acid change T133 M. Presence of these four changes also caused the reversal of enantioselectivity of LinA-type1 for delta-HCH, and beta-, gamma-, and delta-pentachlorocyclohexens. Thus, the residues K20, L96, A131, and T133 in LinA-type1 and the residues Q20, C96, G131, and M133 in LinA-type 2 appear to be important determinants for the enantioselectivity of LinA enzymes.
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| 11. |
- Stenström, John
(författare)
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Using volatile organic compounds to enhance atrazine biodegradation in a biobed system
- 2013
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 24, s. 711-720
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the terpenes alpha-pinene, eucalyptol, and limonene, individually and as mixtures, on atrazine (ATZ) biodegradation and on biological activity in a biobed biomixture was evaluated. Additionally, terpenes emitted from the biomixture were captured using solid-phase microextraction. Terpenes added individually at relatively low concentrations (50 mu g kg(-1)) significantly enhanced ATZ degradation and biological activity during the first incubation days. No significant effect on ATZ degradation was found from adding the terpene mixture, and, interestingly, an inhibitory effect on phenoloxidase activity was found during the first 20 days of incubation when mixed terpenes were present at 100 mu g kg(-1). Capturing terpenes demonstrated that during the first hour of incubation a significant fraction of the terpenes was volatilized. These results are the first to demonstrate the feasibility of using terpenes to enhance the degradation of a pesticide. However, successive applications of terpenes or the addition of materials that slowly release terpenes could sustain the ATZ degradation enhancement.
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| 12. |
- Sundberg, Cecilia, et al.
(författare)
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Process inhibition due to organic acids in fed-batch composting of food waste - Influence of starting culture
- 2005
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Ingår i: Biodegradation. - : Springer. - 0923-9820 .- 1572-9729. ; 16:3, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition of the degradation during low pH conditions has been observed in fed-batch composting systems. To analyse this phenomenon, fed-batch composting of food waste with different amounts of starting culture was examined in laboratory reactor experiments. Changes in temperature, carbon dioxide evolution, pH, solids, ash and short chain organic acids were measured. In reactors with a daily feed rate of 24% or less of the starting culture, thermophilic temperatures occurred and the pH and carbon dioxide evolution were high and stable after a starting period of 4-5 days. In reactors with a daily feed rate of 48% or more of the starting culture the composting process failed, as the pH dropped below 6 and remained there and the temperature and carbon dioxide evolution were low. It was concluded that the use of adequate amounts of starting culture consisting of active compost can efficiently prevent low pH conditions and process inhibition in fed-batch composting of food waste.
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| 13. |
- Unell, Maria, et al.
(författare)
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Degradation of mixtures of phenolic compounds by Arthrobacter chlorophenolicus A6
- 2008
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 19:4, s. 495-505
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Tidskriftsartikel (refereegranskat)abstract
- In this study the chlorophenol-degrading actinobacterium, Arthrobacter chlorophenolicus A6, was tested for its ability to grow on mixtures of phenolic compounds. During the experiments depletion of the compounds was monitored, as were cell growth and activity. Activity assays were based on bioluminescence output from a luciferase-tagged strain. When the cells were grown on a mixture of 4-chlorophenol, 4-nitrophenol and phenol, 4-chlorophenol degradation apparently was delayed until 4-nitrophenol was almost completely depleted. Phenol was degraded more slowly than the other compounds and not until 4-nitrophenol and 4-chlorophenol were depleted, despite this being the least toxic compound of the three. A similar order of degradation was observed in non-sterile soil slurries inoculated with A. chlorophenolicus. The kinetics of degradation of the substituted phenols suggest that the preferential order of their depletion could be due to their respective pKa values and that the dissociated phenolate ions are the substrates. A mutant strain (T99), with a disrupted hydroxyquinol dioxygenase gene in the previously described 4-chlorophenol degradation gene cluster, was also studied for its ability to grow on the different phenols. The mutant strain was able to grow on phenol, but not on either of the substituted phenols, suggesting a different catabolic pathway for the degradation of phenol by this microorganism.
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| 14. |
- Vavilin, V.A., et al.
(författare)
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Modelling MSW decomposition under landfill conditions considering hydrolytic and methanogenic inhibition
- 2006
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 17:5, s. 389-402
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Tidskriftsartikel (refereegranskat)abstract
- A landfill typically progresses through a series of microbial degradation phases, in which hydrolysis, production and consumption of fermentation products, such as fatty acids, and methane formation play important roles. For ultimate degradation of the waste, stable methanogenic conditions have to be attained, and maintained for sufficient time. Using experimental data from 100-L landfill simulation reactors containing municipal solid waste from a residential area, a distributed model, which accounts for vertical water flow, was developed. As a first step, the waste was divided into two fractions: readily degradable and recalcitrant waste. Secondly, the general hydrolysis of the recalcitrant waste was accounted for by including a specific, well-defined chemical substance in the model that generally occurs in Municipal Solid Waste (MSW) and is hydrolysed before its further degradation to methane. For this purpose we chose diethyl phthalate and its hydrolysis product monoethyl phthalate, for which leachate data are available from the reactors. The model indicated that inhibition of the hydrolytic and methanogenic processes occurred during the acidogenic phase and that it could be overcome either by improving the chemical environment or by the complete oxidation of the inhibiting, i.e. the easily degraded, fraction of the waste. The generality of the model was confirmed by the patterns of the phthalate di- and monoester transformations obtained. The validity of the model was further confirmed using experimental data from parallel reactors, which were subjected to either leachate exchange with an already methanogenic reactor or to initial aeration to force the reactor into stable methanogenic conditions. © Springer 2006.
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| 15. |
- Önneby, Karin, et al.
(författare)
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A new concept for reduction of diffuse contamination by simultaneous application of pesticide and pesticide-degrading microorganisms
- 2010
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 21, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Pesticide residues and their transformation products are frequently found in groundwater and surface waters. This study examined whether adding pesticide-degrading microorganisms simultaneously with the pesticide at application could significantly reduce diffuse contamination from pesticide use. Degradation of the phenoxyacetic acid herbicides MCPA (4-chloro-2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) was studied in soil microcosm experiments after simultaneous spraying of herbicide and herbicide-degrading bacteria on an agricultural soil and on a sand with low degradation potential. The latter represented pesticide use on non-agricultural soils poor in microbial activity. Degradation and possible loss of herbicidal effect were also tested in a system with plants and the amounts of bacteria needed to give satisfactory MCPA-degradation rate and the survival of degrading bacteria in formulated MCPA were determined. The results showed > 80-99% degradation of 2,4-D and MCPA in soil within 1 day and > 99% within 3 days after inoculation with 10(5)-10(7) herbicide-degrading bacteria g(-1) dry weight of soil. Enhanced degradation of MCPA was also obtained in the presence of winter wheat and white mustard without loss of the intended herbicidal effect on white mustard. The survival of an isolated MCPA-degrading Sphingomonas sp. in three realistic concentrations of formulated MCPA was very poor, showing that in practical applications direct contact between the microorganisms and the pesticide formulation must be precluded. The applicability and economic feasibility of the method and the information needed to obtain a useable product for field use are discussed.
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| 16. |
- Önneby, Karin, et al.
(författare)
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Reduced leaching of the herbicide MCPA after bioaugmentation with a formulated and stored Sphingobium sp.
- 2014
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 25, s. 291-300
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Tidskriftsartikel (refereegranskat)abstract
- The use of pesticides on sandy soils and on many non-agricultural areas entails a potentially high risk of water contamination. This study examined leaching of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) after bioaugmentation in sand with differently formulated and stored Sphingobium sp. T51 and at different soil moisture contents. Dry formulations of Sphingobium sp. T51 were achieved by either freeze drying or fluidised bed drying, with high initial cell viability of 67-85 %. Storage stability of T51 cells was related to formulation excipient/carrier and storage conditions. Bacterial viability in the fluidised bed-dried formulations stored at 25 A degrees C under non-vacuum conditions was poor, with losses of at least 97 % within a month. The freeze-dried formulations could be stored substantially longer, with cell survival rates of 50 %, after 6 months of storage at the same temperature under partial vacuum. Formulated and long-term stored Sphingobium cells maintained their MCPA degradation efficacy and reduced MCPA leaching as efficiently as freshly cultivated cells, by at least 73 % when equal amounts of viable cells were used. The importance of soil moisture for practical field bioaugmentation techniques is discussed.
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| 17. |
- Bengtsson, Göran, et al.
(författare)
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Degradation of dissolved and sorbed 2,4-dichlorophenol in soil columns by suspended and sorbed bacteria.
- 2001
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Ingår i: Biodegradation. - 0923-9820. ; 12:6, s. 32-419
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Tidskriftsartikel (refereegranskat)abstract
- The influence of sorption of bacteria, as well as 2,4-dichlorophenol (2,4-DCP), on the mineralization of 100 microg l(-1) of the organic compound was examined in an aquifer material under advective flow conditions (column displacement technique). The study was designed to distinguish the rates and extent of biodegradation of the sorbed and the dissolved trace organic and the contribution of sorbed and suspended bacteria to the degradation. The degradation of dissolved 2,4-DCP was significantly faster than the degradation of the same compound sorbed to the solids, and suspended bacteria degraded the dissolved compound at a higher rate than sorbed bacteria, also on a per cell basis. The suspended bacteria degraded 8-12% of the added dissolved 2.4-DCP, while sorbed bacteria made a smaller contribution by degrading about 5% of sorbed 2,4-DCP. No degradation was seen with sorbed 2,4-DCP and suspended bacteria, and a marginal contribution was made by sorbed bacteria on the degradation of dissolved 2,4-DCP (<0.4%).
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| 18. |
- Katsivela, E, et al.
(författare)
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Bacterial community dynamics during in-situ bioremediation of petroleum waste sludge in landfarming sites.
- 2005
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Ingår i: Biodegradation. - 0923-9820. ; 16:2, s. 169-80
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Tidskriftsartikel (refereegranskat)abstract
- In-situ bioremediation of petroleum waste sludge in landfarming sites of Motor Oil Hellas (petroleum refinery) was studied by monitoring the changes of the petroleum composition of the waste sludge, as well as the changes in the structure of the microbial community, for a time period of 14 months. The analyses indicated an enhanced degradation of the petroleum hydrocarbons in the landfarming areas. A depletion of n-alkanes of approximately 75-100% was obtained. Marked changes of the microbial communities of the landfarms occurred concomitantly with the degradation of the petroleum hydrocarbons. The results obtained from terminal restriction fragment length polymorphism (T-RFLP) analysis of polymerase chain reaction (PCR) amplified 16S rRNA genes demonstrated that bacteria originating from the refinery waste sludge and newly selected bacteria dominated the soil bacterial community during the period of the highest degradation activity. However, the diversity of the microbial community was decreased with increased degradation of the petroleum hydrocarbons contained in the landfarms. T-RFLP fingerprints of bacteria of the genera Enterobacter and Ochrobactrum were detected in the landfarmed soil over the entire treatment period of 14 months. In contrast, the genus Alcaligenes appeared in significant numbers only within the 10 month old landfarmed soil. Genes encoding catechol 2,3-dioxygenase (subfamily I.2.A) were detected only in DNA of the untreated refinery waste sludge. However, none of the genes known to encode the enzymes alkane hydroxylase AlkB, catechol 2,3-dioxygenase (subfamily I.2.A) and naphthalene dioxygenase nahAc could be detected in DNA of the landfarmed soils.
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| 19. |
- Gunnarsson, Bengt, 1954, et al.
(författare)
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Bumblebees in the city: abundance, species richness and diversity in two urban habitats
- 2014
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 18:6, s. 1185-1191
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Tidskriftsartikel (refereegranskat)abstract
- Bumblebees are well known for their contribution to the ecosystem service of pollination. In urban areas, green space management beneficial to pollinators can be an important step in sustaining large urban bee populations. The abundance, number of species and diversity of bumblebees (Bombus spp), as well as the abundance of honeybees (Apis mellifera), were studied in 13 urban gardens (including allotments) and 13 ornamental flowerbeds (in parks and green spaces) in the city centre of Gothenburg, Sweden. In total, 12 species of bumblebees were observed. Species richness was significantly higher in gardens than in flowerbeds, but diversity (Berger–Parker and Simpson indices) was higher in flowerbeds than in urban gardens. The abundance in gardens was significantly higher and approximately twice that found in flowerbeds. The number of honeybee individuals was positively correlated with the abundance of bumblebees. Neither species richness nor abundance of bumblebees was affected by site size. However, a high flowering frequency positively affected the total number of bumblebee and honeybee individuals at the sites. We conclude that urban gardens contribute to sustaining a high abundance of bumblebees in the city centre, and indirectly facilitates small scale urban food production. A pollinator-friendly management of urban green space with plentiful flowering may promote a community of bumblebees with high abundance and diversity.
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