Geological Survey of Denmark and Greenland Bulletin
The Danish Pesticide Leaching Assessment Programme (PLAP) was initiated in 1998 by the Danish Par... more The Danish Pesticide Leaching Assessment Programme (PLAP) was initiated in 1998 by the Danish Parliament in order to evaluate whether the use of approved pesticides will result in an unacceptable contamination of the groundwater, if applied under field conditions in accordance with current Danish regulation. In this programme, water samples from variably saturated soil and groundwater collected at five cultivated fields are analysed for selected pesticides and their degradation products. The PLAP results are summarised and evaluated in yearly reports and used by the Danish Environmental Protection Agency in the regulation of pesticides in Denmark (Brüsch et al. 2015). In order to represent typical farming scenarios in Denmark, the test fields are situated on meltwater and marine sands, and on tile-drained clayey soils in till areas.
In this study, we developed a method that provides profiles of community-level surface dispersal ... more In this study, we developed a method that provides profiles of community-level surface dispersal from environmental samples under controlled hydration conditions and enables us to isolate and uncover the diversity of the fastest bacterial dispersers. The method expands on the porous surface model (PSM), previously used to monitor the dispersal of individual bacterial strains in liquid films at the surface of a porous ceramic disc. The novel procedure targets complex communities and captures the dispersed bacteria on a solid medium for growth and detection. The method was first validated by distinguishing motile Pseudomonas putida and Flavobacterium johnsoniae strains from their nonmotile mutants. Applying the method to soil and lake water bacterial communities showed that community-scale dispersal declined as conditions became drier. However, for both communities, dispersal was detected even under low-hydration conditions (matric potential, −3.1 kPa) previously proven too dry for P....
In this study, we developed a method that provides profiles of community-level surface dispersal ... more In this study, we developed a method that provides profiles of community-level surface dispersal from environmental samples under controlled hydration conditions and enables us to isolate and uncover the diversity of the fastest bacterial dispersers. The method expands on the porous surface model (PSM), previously used to monitor the dispersal of individual bacterial strains in liquid films at the surface of a porous ceramic disc. The novel procedure targets complex communities and captures the dispersed bacteria on a solid medium for growth and detection. The method was first validated by distinguishing motile Pseudomonas putida and Flavobacterium johnsoniae strains from their nonmotile mutants. Applying the method to soil and lake water bacterial communities showed that community-scale dispersal declined as conditions became drier. However, for both communities, dispersal was detected even under low-hydration conditions (matric potential, −3.1 kPa) previously proven too dry for P....
Pesticide-polluted drinking water may be remediated by inoculating waterworks sand filters with s... more Pesticide-polluted drinking water may be remediated by inoculating waterworks sand filters with specific degrading bacteria. However, degradation efficiency is often hampered by the poor adhesion behaviour of the introduced bacteria. The phenoxy acid herbicide 4-chloro-2-methyl-phenoxy-acetic acid (MCPA) is a widespread groundwater contaminant. The aim of this study was to investigate whether specific surface characteristics of MCPA-degrading bacteria could be linked to their degrading capabilities in sand filters. Four MCPA degraders with different taxonomic affiliations and original habitats (Sphingomonas sp. PM2, Sphingomonas sp. ERG5, Burkholderia sp. TFD34, Cupriavidus sp. TFD38) were characterised with regard to their motility, cell surface hydrophobicity, biofilm formation, adhesion behaviour and ability to mineralise MCPA. Strains PM2 and ERG5 were non-motile and hydrophobic, whilst strains TFD34 and TFD38 were motile and less hydrophobic. All the strains except ERG5 showed low biofilm formation on polystyrene, although it was significantly higher on glass. PM2 was the most efficient MCPA degrader as it displayed no lag phase and reached >50 % mineralisation at all concentrations (0.0016-25 mg L(-1)). PM2 adhered significantly better to sand than the other strains. No link was found between motility, biofilm formation and the ability to adhere to sand. PM2 completely removed MCPA for 14 days when inoculated in sand columns with a constant inlet of 1 mg L(-1) MCPA. These results demonstrate that besides the ability to degrade the contaminant, surface hydrophobicity and adherence abilities are significant parameters controlling sustained degradation in flow-through sand columns and must be considered when selecting bacteria for bioaugmentation.
The ability to disperse is considered essential for soil bacteria colonization and survival, yet ... more The ability to disperse is considered essential for soil bacteria colonization and survival, yet very little is known about the dispersal ability of communities from different heterogeneous soil compartments. Important factors for dispersal are the thickness and connectivity of the liquid film between soil particles. The present results from a fractured clay till depth profile suggest that dispersal ability is common in various soil compartments and that most are dominated by a few dispersing taxa. Importantly, an increase in shared dispersers among the preferential flow paths of the clay till suggests that active dispersal plays a role in the successful colonization of these habitats.
Geological Survey of Denmark and Greenland Bulletin
The Danish Pesticide Leaching Assessment Programme (PLAP) was initiated in 1998 by the Danish Par... more The Danish Pesticide Leaching Assessment Programme (PLAP) was initiated in 1998 by the Danish Parliament in order to evaluate whether the use of approved pesticides will result in an unacceptable contamination of the groundwater, if applied under field conditions in accordance with current Danish regulation. In this programme, water samples from variably saturated soil and groundwater collected at five cultivated fields are analysed for selected pesticides and their degradation products. The PLAP results are summarised and evaluated in yearly reports and used by the Danish Environmental Protection Agency in the regulation of pesticides in Denmark (Brüsch et al. 2015). In order to represent typical farming scenarios in Denmark, the test fields are situated on meltwater and marine sands, and on tile-drained clayey soils in till areas.
In this study, we developed a method that provides profiles of community-level surface dispersal ... more In this study, we developed a method that provides profiles of community-level surface dispersal from environmental samples under controlled hydration conditions and enables us to isolate and uncover the diversity of the fastest bacterial dispersers. The method expands on the porous surface model (PSM), previously used to monitor the dispersal of individual bacterial strains in liquid films at the surface of a porous ceramic disc. The novel procedure targets complex communities and captures the dispersed bacteria on a solid medium for growth and detection. The method was first validated by distinguishing motile Pseudomonas putida and Flavobacterium johnsoniae strains from their nonmotile mutants. Applying the method to soil and lake water bacterial communities showed that community-scale dispersal declined as conditions became drier. However, for both communities, dispersal was detected even under low-hydration conditions (matric potential, −3.1 kPa) previously proven too dry for P....
In this study, we developed a method that provides profiles of community-level surface dispersal ... more In this study, we developed a method that provides profiles of community-level surface dispersal from environmental samples under controlled hydration conditions and enables us to isolate and uncover the diversity of the fastest bacterial dispersers. The method expands on the porous surface model (PSM), previously used to monitor the dispersal of individual bacterial strains in liquid films at the surface of a porous ceramic disc. The novel procedure targets complex communities and captures the dispersed bacteria on a solid medium for growth and detection. The method was first validated by distinguishing motile Pseudomonas putida and Flavobacterium johnsoniae strains from their nonmotile mutants. Applying the method to soil and lake water bacterial communities showed that community-scale dispersal declined as conditions became drier. However, for both communities, dispersal was detected even under low-hydration conditions (matric potential, −3.1 kPa) previously proven too dry for P....
Pesticide-polluted drinking water may be remediated by inoculating waterworks sand filters with s... more Pesticide-polluted drinking water may be remediated by inoculating waterworks sand filters with specific degrading bacteria. However, degradation efficiency is often hampered by the poor adhesion behaviour of the introduced bacteria. The phenoxy acid herbicide 4-chloro-2-methyl-phenoxy-acetic acid (MCPA) is a widespread groundwater contaminant. The aim of this study was to investigate whether specific surface characteristics of MCPA-degrading bacteria could be linked to their degrading capabilities in sand filters. Four MCPA degraders with different taxonomic affiliations and original habitats (Sphingomonas sp. PM2, Sphingomonas sp. ERG5, Burkholderia sp. TFD34, Cupriavidus sp. TFD38) were characterised with regard to their motility, cell surface hydrophobicity, biofilm formation, adhesion behaviour and ability to mineralise MCPA. Strains PM2 and ERG5 were non-motile and hydrophobic, whilst strains TFD34 and TFD38 were motile and less hydrophobic. All the strains except ERG5 showed low biofilm formation on polystyrene, although it was significantly higher on glass. PM2 was the most efficient MCPA degrader as it displayed no lag phase and reached >50 % mineralisation at all concentrations (0.0016-25 mg L(-1)). PM2 adhered significantly better to sand than the other strains. No link was found between motility, biofilm formation and the ability to adhere to sand. PM2 completely removed MCPA for 14 days when inoculated in sand columns with a constant inlet of 1 mg L(-1) MCPA. These results demonstrate that besides the ability to degrade the contaminant, surface hydrophobicity and adherence abilities are significant parameters controlling sustained degradation in flow-through sand columns and must be considered when selecting bacteria for bioaugmentation.
The ability to disperse is considered essential for soil bacteria colonization and survival, yet ... more The ability to disperse is considered essential for soil bacteria colonization and survival, yet very little is known about the dispersal ability of communities from different heterogeneous soil compartments. Important factors for dispersal are the thickness and connectivity of the liquid film between soil particles. The present results from a fractured clay till depth profile suggest that dispersal ability is common in various soil compartments and that most are dominated by a few dispersing taxa. Importantly, an increase in shared dispersers among the preferential flow paths of the clay till suggests that active dispersal plays a role in the successful colonization of these habitats.
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Papers by Nora Badawi