{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:61703"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:61703","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Bacteria transport under unsaturated conditions","abstract":"The aim of this work was to study the bacteria transport behaviour in different conditions using an unsaturated porous media. A column based system able to keep the unsaturated conditions was designed and developed to perform the experiments. Two bacteria strains Deinococcus radiodurans and Rhodococcus rhodochrous strongly different in hydrophobicity were employed. During the experiments the bacteria concentration in the outflow was continuously on-line measured and after the experiment the column has been dismantled to determine the retention profile. The observed data were fitted using two different models (Tufenkji et al. 2003, 2004, 2005 and Bradford et al. 2003) and the resulting coefficients were used to elucidate the transport mechanisms. Following aspects concerning the bacteria transport behaviour were investigated: (i) the influence of matrix saturation; (ii) the role of the bacteria surface characteristic; (iii) the effect of matrix grain size; (iv) the transport behaviour of metabolically active bacteria; for the first time, fresh bacteria cells supplied with nutrients during the experiments were used to be more close to the real situation experienced in the soil. (v) the role of bacteria surface the protein; bacteria were treated with the enzyme alpha-Chemotrypsin to remove the surface protein. It was found that bacteria transport through variably saturated porous media was directly related to water content. The trend observed for both strains was that decreasing water content inside the porous media led to a decreasing cells effluent concentration and an increasing amount of retained bacteria. This effect was more pronounced for hydrophobic bacteria. Concerning the retention profile it was established that the bacteria location inside the packing did not follow a disposition predictable with the classical filtration theory. The most of the bacteria amount was found in the first sand centimetres below the inlet and a monotonical decrease of the bacteria amount with the depth was observed. This effect was directly related to the packing water content and the bacteria hydrophobicity: decreasing the water content a higher bacteria amount was found close to the column inlet and this effect was more pronounced in the case of more hydrophobic bacteria. According to the “straining” model, at fully saturation the more hydrophobic strain showed a higher adhesion rate compared with the hydrophilic one. The results highlight that for the hydrophilic strain the adhesion to the air-water-solid interface was the main removal mechanism. In contrast, the main removal mechanism for the hydrophobic strain was the straining: due to their aggregation behaviour the cells were filtered out from the solution bulk. The coefficients resulting from the fitting using the dual deposition mode model showed that the fraction of bacteria with a fast adhesion increased decreasing the saturation. The hydrophobic strain showed always the higher adhesion rate and for both strains the adhesion rate increased with decreasing saturation. The packing grain size was an important factor for the bacteria transport: different pore size led to a different interaction between the bacteria and the grain surface. In the case of fine sand (330µm) a strong filter-out effect in the first centimetres after the inlet was observed causing a strongly reduced bacteria transport. For the coarse sand (607µm) the interaction bacteria/sand surface was reduced and nearly all the cells were able to pass the packing. The fitted parameter calculated with the “straining” model showed that both the adhesion rate and the straining rate increased when the grain size decreased. Applying the dual deposition mode model, two different approaches were used to fit the experimental data concerning the fine sand. In the first case two discrete rate coefficients were used and both fitting parameters increased with decreasing sand grain size. In the second case only one attachment rate was supposed to be the important for the bacteria adhesion through the porous system and this approach could better describe the experimental data. Metabolically active bacteria during the transport showed a different behaviour compared with “resting cell” bacteria. Cells in the log phase were retained in the column more than in the stationary phase and a continuous release after the breakthrough curve was observed in the outflow. During the transport bacteria in active phase did not show blocking evidences. The growing cells showed an increasing hydrophobicity during the log phase. This effect was attributed in particular to the changes in amount and type of the proteins present on the bacteria surface. Chemically treated bacteria without protein showed less adhesion to the sand surface and the transport was enhanced by this treatment. According to the “straining” model the bacteria enzymatically treated showed a decrease in the adhesion rate while the straining rate was not effected. Using the dual deposition mode model both the adhesion rates decreased in the case of the treated bacteria. Further experiment should be performed under these conditions with other strains to better understand the effect of proteins and eventually protein associated macromolecules on the bacteria adhesion to the surface.","abstract_html":"The aim of this work was to study the bacteria transport behaviour in different conditions using an unsaturated porous media. A column based system able to keep the unsaturated conditions was designed and developed to perform the experiments. Two bacteria strains Deinococcus radiodurans and Rhodococcus rhodochrous strongly different in hydrophobicity were employed. During the experiments the bacteria concentration in the outflow was continuously on-line measured and after the experiment the column has been dismantled to determine the retention profile. The observed data were fitted using two different models (Tufenkji et al. 2003, 2004, 2005 and Bradford et al. 2003) and the resulting coefficients were used to elucidate the transport mechanisms. Following aspects concerning the bacteria transport behaviour were investigated: (i) the influence of matrix saturation; (ii) the role of the bacteria surface characteristic; (iii) the effect of matrix grain size; (iv) the transport behaviour of metabolically active bacteria; for the first time, fresh bacteria cells supplied with nutrients during the experiments were used to be more close to the real situation experienced in the soil. (v) the role of bacteria surface the protein; bacteria were treated with the enzyme alpha-Chemotrypsin to remove the surface protein. It was found that bacteria transport through variably saturated porous media was directly related to water content. The trend observed for both strains was that decreasing water content inside the porous media led to a decreasing cells effluent concentration and an increasing amount of retained bacteria. This effect was more pronounced for hydrophobic bacteria. Concerning the retention profile it was established that the bacteria location inside the packing did not follow a disposition predictable with the classical filtration theory. The most of the bacteria amount was found in the first sand centimetres below the inlet and a monotonical decrease of the bacteria amount with the depth was observed. This effect was directly related to the packing water content and the bacteria hydrophobicity: decreasing the water content a higher bacteria amount was found close to the column inlet and this effect was more pronounced in the case of more hydrophobic bacteria. According to the “straining” model, at fully saturation the more hydrophobic strain showed a higher adhesion rate compared with the hydrophilic one. The results highlight that for the hydrophilic strain the adhesion to the air-water-solid interface was the main removal mechanism. In contrast, the main removal mechanism for the hydrophobic strain was the straining: due to their aggregation behaviour the cells were filtered out from the solution bulk. The coefficients resulting from the fitting using the dual deposition mode model showed that the fraction of bacteria with a fast adhesion increased decreasing the saturation. The hydrophobic strain showed always the higher adhesion rate and for both strains the adhesion rate increased with decreasing saturation. The packing grain size was an important factor for the bacteria transport: different pore size led to a different interaction between the bacteria and the grain surface. In the case of fine sand (330µm) a strong filter-out effect in the first centimetres after the inlet was observed causing a strongly reduced bacteria transport. For the coarse sand (607µm) the interaction bacteria/sand surface was reduced and nearly all the cells were able to pass the packing. The fitted parameter calculated with the “straining” model showed that both the adhesion rate and the straining rate increased when the grain size decreased. Applying the dual deposition mode model, two different approaches were used to fit the experimental data concerning the fine sand. In the first case two discrete rate coefficients were used and both fitting parameters increased with decreasing sand grain size. In the second case only one attachment rate was supposed to be the important for the bacteria adhesion through the porous system and this approach could better describe the experimental data. Metabolically active bacteria during the transport showed a different behaviour compared with “resting cell” bacteria. Cells in the log phase were retained in the column more than in the stationary phase and a continuous release after the breakthrough curve was observed in the outflow. During the transport bacteria in active phase did not show blocking evidences. The growing cells showed an increasing hydrophobicity during the log phase. This effect was attributed in particular to the changes in amount and type of the proteins present on the bacteria surface. Chemically treated bacteria without protein showed less adhesion to the sand surface and the transport was enhanced by this treatment. According to the “straining” model the bacteria enzymatically treated showed a decrease in the adhesion rate while the straining rate was not effected. Using the dual deposition mode model both the adhesion rates decreased in the case of the treated bacteria. Further experiment should be performed under these conditions with other strains to better understand the effect of proteins and eventually protein associated macromolecules on the bacteria adhesion to the surface.","abstract_has_math":false,"creators":["Gargiulo, Grazia"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Schäffer, Andreas"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2007,"date_issued":"2007","date_published":"2007","updated_at":"2026-07-30T19:43:10Z","subjects":["info:eu-repo/classification/ddc/570","Biowissenschaften, Biologie","Deinococcus radiodurans","Rhodococcus rhodochrous","Advektion-Diffusionsgleichung","Bodenbakterien","Transport","unsaturated system","vadose zone","modeling"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123338%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123338%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123338%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/61703","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Schäffer, Andreas"]},{"key":"dc:creator","label":"Author","values":["Gargiulo, Grazia"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2007"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-17817"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/570","Biowissenschaften, Biologie","Deinococcus radiodurans","Rhodococcus rhodochrous","Advektion-Diffusionsgleichung","Bodenbakterien","Transport","unsaturated system","vadose zone","modeling"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/61703","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123338%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The aim of this work was to study the bacteria transport behaviour in different conditions using an unsaturated porous media. A column based system able to keep the unsaturated conditions was designed and developed to perform the experiments. Two bacteria strains Deinococcus radiodurans and Rhodococcus rhodochrous strongly different in hydrophobicity were employed. During the experiments the bacteria concentration in the outflow was continuously on-line measured and after the experiment the column has been dismantled to determine the retention profile. The observed data were fitted using two different models (Tufenkji et al. 2003, 2004, 2005 and Bradford et al. 2003) and the resulting coefficients were used to elucidate the transport mechanisms. Following aspects concerning the bacteria transport behaviour were investigated: (i) the influence of matrix saturation; (ii) the role of the bacteria surface characteristic; (iii) the effect of matrix grain size; (iv) the transport behaviour of metabolically active bacteria; for the first time, fresh bacteria cells supplied with nutrients during the experiments were used to be more close to the real situation experienced in the soil. (v) the role of bacteria surface the protein; bacteria were treated with the enzyme alpha-Chemotrypsin to remove the surface protein. It was found that bacteria transport through variably saturated porous media was directly related to water content. The trend observed for both strains was that decreasing water content inside the porous media led to a decreasing cells effluent concentration and an increasing amount of retained bacteria. This effect was more pronounced for hydrophobic bacteria. Concerning the retention profile it was established that the bacteria location inside the packing did not follow a disposition predictable with the classical filtration theory. The most of the bacteria amount was found in the first sand centimetres below the inlet and a monotonical decrease of the bacteria amount with the depth was observed. This effect was directly related to the packing water content and the bacteria hydrophobicity: decreasing the water content a higher bacteria amount was found close to the column inlet and this effect was more pronounced in the case of more hydrophobic bacteria. According to the “straining” model, at fully saturation the more hydrophobic strain showed a higher adhesion rate compared with the hydrophilic one. The results highlight that for the hydrophilic strain the adhesion to the air-water-solid interface was the main removal mechanism. In contrast, the main removal mechanism for the hydrophobic strain was the straining: due to their aggregation behaviour the cells were filtered out from the solution bulk. The coefficients resulting from the fitting using the dual deposition mode model showed that the fraction of bacteria with a fast adhesion increased decreasing the saturation. The hydrophobic strain showed always the higher adhesion rate and for both strains the adhesion rate increased with decreasing saturation. The packing grain size was an important factor for the bacteria transport: different pore size led to a different interaction between the bacteria and the grain surface. In the case of fine sand (330µm) a strong filter-out effect in the first centimetres after the inlet was observed causing a strongly reduced bacteria transport. For the coarse sand (607µm) the interaction bacteria/sand surface was reduced and nearly all the cells were able to pass the packing. The fitted parameter calculated with the “straining” model showed that both the adhesion rate and the straining rate increased when the grain size decreased. Applying the dual deposition mode model, two different approaches were used to fit the experimental data concerning the fine sand. In the first case two discrete rate coefficients were used and both fitting parameters increased with decreasing sand grain size. In the second case only one attachment rate was supposed to be the important for the bacteria adhesion through the porous system and this approach could better describe the experimental data. Metabolically active bacteria during the transport showed a different behaviour compared with “resting cell” bacteria. Cells in the log phase were retained in the column more than in the stationary phase and a continuous release after the breakthrough curve was observed in the outflow. During the transport bacteria in active phase did not show blocking evidences. The growing cells showed an increasing hydrophobicity during the log phase. This effect was attributed in particular to the changes in amount and type of the proteins present on the bacteria surface. Chemically treated bacteria without protein showed less adhesion to the sand surface and the transport was enhanced by this treatment. According to the “straining” model the bacteria enzymatically treated showed a decrease in the adhesion rate while the straining rate was not effected. Using the dual deposition mode model both the adhesion rates decreased in the case of the treated bacteria. Further experiment should be performed under these conditions with other strains to better understand the effect of proteins and eventually protein associated macromolecules on the bacteria adhesion to the surface."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University IV, 103 S. : Ill., graph. Darst. (2007). = Aachen, Techn. Hochsch., Diss., 2006"]},{"key":"dc:title","label":"Title","values":["Bacteria transport under unsaturated conditions"]}]}],"canonical_facts":{"dc:contributor":["Schäffer, Andreas"],"dc:coverage":["DE"],"dc:creator":["Gargiulo, Grazia"],"dc:date":["2007"],"dc:description":["The aim of this work was to study the bacteria transport behaviour in different conditions using an unsaturated porous media. A column based system able to keep the unsaturated conditions was designed and developed to perform the experiments. Two bacteria strains Deinococcus radiodurans and Rhodococcus rhodochrous strongly different in hydrophobicity were employed. During the experiments the bacteria concentration in the outflow was continuously on-line measured and after the experiment the column has been dismantled to determine the retention profile. The observed data were fitted using two different models (Tufenkji et al. 2003, 2004, 2005 and Bradford et al. 2003) and the resulting coefficients were used to elucidate the transport mechanisms. Following aspects concerning the bacteria transport behaviour were investigated: (i) the influence of matrix saturation; (ii) the role of the bacteria surface characteristic; (iii) the effect of matrix grain size; (iv) the transport behaviour of metabolically active bacteria; for the first time, fresh bacteria cells supplied with nutrients during the experiments were used to be more close to the real situation experienced in the soil. (v) the role of bacteria surface the protein; bacteria were treated with the enzyme alpha-Chemotrypsin to remove the surface protein. It was found that bacteria transport through variably saturated porous media was directly related to water content. The trend observed for both strains was that decreasing water content inside the porous media led to a decreasing cells effluent concentration and an increasing amount of retained bacteria. This effect was more pronounced for hydrophobic bacteria. Concerning the retention profile it was established that the bacteria location inside the packing did not follow a disposition predictable with the classical filtration theory. The most of the bacteria amount was found in the first sand centimetres below the inlet and a monotonical decrease of the bacteria amount with the depth was observed. This effect was directly related to the packing water content and the bacteria hydrophobicity: decreasing the water content a higher bacteria amount was found close to the column inlet and this effect was more pronounced in the case of more hydrophobic bacteria. According to the “straining” model, at fully saturation the more hydrophobic strain showed a higher adhesion rate compared with the hydrophilic one. The results highlight that for the hydrophilic strain the adhesion to the air-water-solid interface was the main removal mechanism. In contrast, the main removal mechanism for the hydrophobic strain was the straining: due to their aggregation behaviour the cells were filtered out from the solution bulk. The coefficients resulting from the fitting using the dual deposition mode model showed that the fraction of bacteria with a fast adhesion increased decreasing the saturation. The hydrophobic strain showed always the higher adhesion rate and for both strains the adhesion rate increased with decreasing saturation. The packing grain size was an important factor for the bacteria transport: different pore size led to a different interaction between the bacteria and the grain surface. In the case of fine sand (330µm) a strong filter-out effect in the first centimetres after the inlet was observed causing a strongly reduced bacteria transport. For the coarse sand (607µm) the interaction bacteria/sand surface was reduced and nearly all the cells were able to pass the packing. The fitted parameter calculated with the “straining” model showed that both the adhesion rate and the straining rate increased when the grain size decreased. Applying the dual deposition mode model, two different approaches were used to fit the experimental data concerning the fine sand. In the first case two discrete rate coefficients were used and both fitting parameters increased with decreasing sand grain size. In the second case only one attachment rate was supposed to be the important for the bacteria adhesion through the porous system and this approach could better describe the experimental data. Metabolically active bacteria during the transport showed a different behaviour compared with “resting cell” bacteria. Cells in the log phase were retained in the column more than in the stationary phase and a continuous release after the breakthrough curve was observed in the outflow. During the transport bacteria in active phase did not show blocking evidences. The growing cells showed an increasing hydrophobicity during the log phase. This effect was attributed in particular to the changes in amount and type of the proteins present on the bacteria surface. Chemically treated bacteria without protein showed less adhesion to the sand surface and the transport was enhanced by this treatment. According to the “straining” model the bacteria enzymatically treated showed a decrease in the adhesion rate while the straining rate was not effected. Using the dual deposition mode model both the adhesion rates decreased in the case of the treated bacteria. Further experiment should be performed under these conditions with other strains to better understand the effect of proteins and eventually protein associated macromolecules on the bacteria adhesion to the surface."],"dc:identifier":["https://publications.rwth-aachen.de/record/61703","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123338%22"],"dc:language":["eng"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-17817"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University IV, 103 S. : Ill., graph. Darst. (2007). = Aachen, Techn. Hochsch., Diss., 2006"],"dc:subject":["info:eu-repo/classification/ddc/570","Biowissenschaften, Biologie","Deinococcus radiodurans","Rhodococcus rhodochrous","Advektion-Diffusionsgleichung","Bodenbakterien","Transport","unsaturated system","vadose zone","modeling"],"dc:title":["Bacteria transport under unsaturated conditions"],"dc:type":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-30T19:43:10Z"}