Mixing-controlled biodegradation in a toluene plume — Results from two-dimensional laboratory experiments

Bauer, Robert; Małoszewski, Piotr; Zhang, Yan-Chun; Meckenstock, Rainer U.; Griebler, Christian

doi:10.1016/j.jconhyd.2007.10.008

Cited by 88 publications

(86 citation statements)

References 47 publications

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“…Strain EbN1 represents a promising model organism for in situ processes, since toluene-amended microcosms from oil-contaminated and pristine sites displayed rapid consumption of nitrate (31) and contained high numbers of bacteria related to the phylogenetic cluster harboring strain EbN1 (20,31). Correspondingly, strain EbN1 removes toluene with high efficiency in laboratory twodimensional aquifer microcosms which mimic in situ concentration gradients (2). Moreover, the detection of bssA expression (BssA is the catalytic subunit of toluene-activating benzylsuccinate synthase) in contaminated aquifers (3,53) further emphasized the significance of anaerobic degradation for in situ bioremediation.…”

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confidence: 99%

Solvent Stress Response of the Denitrifying Bacterium “ Aromatoleum aromaticum ” Strain EbN1

Trautwein

Kühner

Wöhlbrand

et al. 2008

Appl Environ Microbiol

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The denitrifying betaproteobacterium "Aromatoleum aromaticum" strain EbN1 degrades several aromatic compounds, including ethylbenzene, toluene, p-cresol, and phenol, under anoxic conditions. The hydrophobicity of these aromatic solvents determines their toxic properties. Here, we investigated the response of strain EbN1 to aromatic substrates at semi-inhibitory (about 50% growth inhibition) concentrations under two different conditions: first, during anaerobic growth with ethylbenzene (0.32 mM) or toluene (0.74 mM); and second, when anaerobic succinate-utilizing cultures were shocked with ethylbenzene (0.5 mM), toluene (1.2 mM), p-cresol (3.0 mM), and phenol (6.5 mM) as single stressors or as a mixture (total solvent concentration, 2.7 mM). Under all tested conditions impaired growth was paralleled by decelerated nitrate-nitrite consumption. Additionally, alkylbenzene-utilizing cultures accumulated poly(3-hydroxybutyrate) (PHB) up to 10% of the cell dry weight. These physiological responses were also reflected on the proteomic level (as determined by two-dimensional difference gel electrophoresis), e.g., up-regulation of PHB granule-associated phasins, cytochrome cd 1 nitrite reductase of denitrification, and several proteins involved in oxidative (e.g., SodB) and general (e.g., ClpB) stress responses.

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confidence: 99%

Solvent Stress Response of the Denitrifying Bacterium “ Aromatoleum aromaticum ” Strain EbN1

Trautwein

Kühner

Wöhlbrand

et al. 2008

Appl Environ Microbiol

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“…Sampling at scales too large may lead to paradox patterns such as overlapping of both electron acceptors and electron donors without reaction, as detailed in Bauer et al (2008) or Bertrand et al (2016). These authors conclude that there must be one or more additional factors limiting biodegradation.…”

Section: Sampling Micro Scale Variabilitymentioning

confidence: 99%

“…These authors conclude that there must be one or more additional factors limiting biodegradation. Such a factor might be the availability of resources in micro pores, as shown conceptually above, which is still at a scale too small to be measured even with the sophisticated setup of Bauer et al (2008).…”

Section: Sampling Micro Scale Variabilitymentioning

confidence: 99%

Towards an integrated understanding of how micro scale processes shape groundwater ecosystem functions

Schmidt

Cuthbert

Schwientek

2017

Science of The Total Environment

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“…the fringe area) where bacteria, contaminant, and electron donor overlap. In a recent study of biodegradation of a contaminant plume using a two-dimensional microcosm, the plume fringe was found to be in the range of 0-2.4 cm for various experimental conditions (R. D. Bauer et al 2008). Chemotaxis may enhance degradation of contaminant plumes when degradation takes place in such a small area.…”

Section: Continuous Injections Below Attractant At 2 CM Spacingmentioning

confidence: 98%

“…Various studies have used two-dimensional microcosms to determine the hydrodynamic properties of porous media such as transverse dispersivity (Cirpka et al 2006;Olsson & Grathwohl 2007;Rahman et al 2005), biodegradation in contaminant plumes (Bauer et al 2008;Bauer, Rolle, Kürzinger, et al 2009;Huang et al 2003;Thullner et al 2004), and the migration of chemotactic bacteria (Liu 2011;Strobel et al 2011). Recent two-dimensional microcosm experiments have corroborated that degradation occurs at the plume fringe where mixing is largely controlled by transverse dispersion of the contaminant, electron acceptor and bacteria from the bulk groundwater across the contaminant plume (Bauer et al 2008;Bauer, Rolle, Kürzinger, et al 2009;Cirpka et al 2006;Rahman et al 2005;Thornton et al 2001). It is important to understand both the processes limiting degradation and the physical regions of increased degradation in order to efficiently clean up in situ contaminant plumes.…”

Section: Two Dimensional Microcosmsmentioning

confidence: 99%

Transverse Migration of Chemotactic Bacteria Toward Chemical Attractants in a Two Dimensional Microcosm with Converctive Flow

Boser

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Bioremediation is often limited by the inability to bring populations of bacteria capable of degradation into contact with groundwater contaminants. Chemotaxis, the ability of bacteria to sense a chemical gradient and swim preferentially towards locations of high concentration, can enhance the biased transport of bacteria. Improving bacterial transport to contaminant sources in groundwater aquifers offers a way to potentially improve the overall effectiveness of in situ bioremediation. A two-dimensional microcosm packed with quartz sand was used to quantify the effect of chemotaxis on the migration of bacteria in porous media. Aqueous media was pumped across the microcosm at approximately 1 m/day to simulate the conditions found naturally in a groundwater aquifer. A plume of sodium benzoate was continuously injected into the microcosm to create an attractant gradient transverse to flow. The chemotactic bacteria, Pseudomonas putida F1, or the nonchemotactic mutant, Pseudomonas putida F1 CheA, were injected with a fluorescent tracer above or below the attractant. A moment analysis was implemented to estimate the center of mass, variance, and skewness of the concentration profiles.The transverse dispersion coefficient and the transverse dispersivity transport parameters were also determined.Results show that the center of mass for the chemotactic bacteria was closer to the attractant source on average than the nonchemotactic control when compared to the uranine tracer for experiments using a pulse injection of bacteria. Experiments were also performed using a continuous injection of bacteria and the center of mass for chemotactic bacteria was closer to the attractant source on average than the nonchemotactic control when compared to the uranine tracer. These results showed that chemotaxis can increase bacterial transport toward iv contaminants, potentially enhancing in situ bioremediation. Experiments with 3 cm and 2 cm spacing between bacteria and attractant were performed to explore the relationship between the exposure time of the bacteria to attractant and the transverse migration of bacteria due to chemotaxis. A difference was not found between the experimental results for 3 cm spacing and 2 cm spacing.Experimentally determined transport parameters were used as input to a two-dimensional mathematical model. Modeling was used to test the effects of changing the chemotactic sensitivity coefficient and the chemotaxis receptor constant at three different bacteria and attractant separation distances: 4 cm, 3 cm, and 2 cm. A chemotactic sensitivity coefficient of 10 -4 cm 2 /s was found to match the change in center of mass determined experimentally for 3 cm and 2 cm separation distances. Model results showed the center of mass shift for chemotactic bacteria was greater for 3 cm and 2 cm spacing than 4 cm spacing at constant chemotactic sensitivity coefficient values, which shows that increasing the exposure time of the bacteria to the attractant can increase the transverse migration of bacteria. Mathematica...

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Mixing-controlled biodegradation in a toluene plume — Results from two-dimensional laboratory experiments

Cited by 88 publications

References 47 publications

Solvent Stress Response of the Denitrifying Bacterium “ Aromatoleum aromaticum ” Strain EbN1

Solvent Stress Response of the Denitrifying Bacterium “ Aromatoleum aromaticum ” Strain EbN1

Towards an integrated understanding of how micro scale processes shape groundwater ecosystem functions

Transverse Migration of Chemotactic Bacteria Toward Chemical Attractants in a Two Dimensional Microcosm with Converctive Flow

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