Quantification of Bacterial Chemotaxis in Porous Media Using Magnetic Resonance Imaging

Olson, Mira S.; Ford, Roseanne M.; Smith, James A.; Fernandez, Erik J.

doi:10.1021/es035236s

Cited by 94 publications

(90 citation statements)

References 30 publications

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“…In heterogeneous systems, bacterial motility is often biased by chemotaxis that guides bacteria toward higher concentrations of nutrients (or away from toxic compounds) [Fenchel, 2002;Stocker et al, 2008]. Chemotaxis has been observed in soil where motile bacteria show chemotactic response to a variety of pollutants considered as potential nutrient sources [Parales et al, 2000;Olson et al, 2004;Kohlmeier et al, 2005;Ford and Harvey, 2007].…”

Section: Introductionmentioning

confidence: 99%

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

Ebrahimi

2014

Water Resources Research

110

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The dispersal rates of self-propelled microorganisms affect their spatial interactions and the ecological functioning of microbial communities. Microbial dispersal rates affect risk of contamination of water resources by soil-borne pathogens, the inoculation of plant roots, or the rates of spoilage of food products. In contrast with the wealth of information on microbial dispersal in water replete systems, very little is known about their dispersal rates in unsaturated porous media. The fragmented aqueous phase occupying complex soil pore spaces suppress motility and limits dispersal ranges in unsaturated soil. The primary objective of this study was to systematically evaluate key factors that shape microbial dispersal in model unsaturated porous media to quantify effects of saturation, pore space geometry, and chemotaxis on characteristics of principles that govern motile microbial dispersion in unsaturated soil. We constructed a novel 3-D angular pore network model (PNM) to mimic aqueous pathways in soil for different hydration conditions; within the PNM, we employed an individual-based model that considers physiological and biophysical properties of motile and chemotactic bacteria. The effects of hydration conditions on first passage times in different pore networks were studied showing that fragmentation of aquatic habitats under dry conditions sharply suppresses nutrient transport and microbial dispersal rates in good agreement with limited experimental data. Chemotactically biased mean travel speed of microbial cells across 9 mm saturated PNM was $3 mm/h decreasing exponentially to 0.45 mm/h for the PNM at matric potential of 215 kPa (for 235 kPa, dispersal practically ceases and the mean travel time to traverse the 9 mm PNM exceeds 1 year). Results indicate that chemotaxis enhances dispersal rates by orders of magnitude relative to random (diffusive) motions. Model predictions considering microbial cell sizes relative to available liquid pathways sizes were in good agreement with experimental results for unsaturated soils. The new modeling platform enables quantitative consideration of key biophysical factors (e.g., pore space heterogeneities and hydration conditions) governing microbial interactions in 3-D soil pore spaces.

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Section: Introductionmentioning

confidence: 99%

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

Ebrahimi

2014

Water Resources Research

110

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“…The porosity e cancels out in the mass balance equations, because the porous medium is homogeneous. We also assumed the tortuosities of the substrate and bacteria to be equal (they are different, if the pore size is on the order of the mean bacterial run length or smaller [Olson et al, 2004]). Via a Galilean transformation, b(x, t) = b 0 (x 0 , t 0 ) and …”

Section: Band Formation From a Long Cell Slug In Porous Mediamentioning

confidence: 99%

Lattice‐Boltzmann modeling of contaminant degradation by chemotactic bacteria: Exploring the formation and movement of bacterial bands

Long

Hilpert

2008

Water Resources Research

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[1] We developed a three-dimensional Lattice-Boltzmann (LB) model to simulate the biodegradation of a dissolved substrate, toward which bacteria exhibit chemotaxis. The model was verified by comparing simulations to capillary assay experiments performed elsewhere. In these assays, a capillary containing an aqueous solution, with initially uniformly distributed dissolved naphthalene, was dipped into a reservoir containing Pseudomonas putida, a microorganism that exhibits chemotaxis to naphthalene. These experiments were also performed with additional glass beads present in the capillary and reservoir. The simulations show that a fraction of the bacteria separates from the reservoir to form a band that moves with constant speed into the capillary while metabolizing the naphthalene. We also used the LB model to explore band formation in a porous medium under groundwater flow conditions. If a bacterial slug is injected, two bacterial bands form; one moves upstream and the other moves downstream. The magnitudes of the two band velocities, as measured relative to the pore water velocity, are identical. Bacteria injected in excess are advected downstream in a fluid parcel containing no substrate. Our simulations suggest that the bioremediation of a contaminant plume in groundwater can potentially be enhanced by the injection of chemotactic bacteria. We also derived a correlation that predicts the number of bacteria in a band that separates from a semi-infinite bacterial slug in a domain containing substrate that is initially uniformly distributed. This correlation allows estimation of the optimal number of bacteria that needs to be added to a substrate-filled domain, such that the number of bacteria in the band is maximum while simultaneously avoiding the injection of excess bacteria that do not make it into the band.

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“…In most of the published literature, chemotaxis is taken into account. The effective motility of bacteria through permeable (sandy) porous media lies between 10 [3,36,35]. As we neglect chemotaxis and focus on less permeable sediments, we assume that the diffusion coefficients of the organisms are in general even smaller, approximately 3 − 5 orders of magnitude.…”

Section: Model Formulationmentioning

confidence: 99%

Pattern Formation of Competing Microorganisms in Sediments

Schmitz

Baurmann

Engelen

et al. 2007

Math. Model. Nat. Phenom.

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Abstract. We present a three species model describing the degradation of substrate by two competing populations of microorganisms in a marine sediment. Considering diffusion to be the main transport process, we obtain a reaction diffusion system (RDS) which we study in terms of spontaneous pattern formation. We find that the conditions for patterns to evolve are likely to be fulfilled in the sediment. Additionally, we present simulations that are consistent with experimental data from the literature. We focus on the interaction between pattern formation and non-uniform forcing, which naturally occurs in our model, since layers closer to the sea water are richer in particular chemicals than deeper layers. We find that heterogeneous forcing has a strong impact on the structures that evolve, leading to the formation of banded structures or even pulses instead of the well-known Turing patterns.

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Quantification of Bacterial Chemotaxis in Porous Media Using Magnetic Resonance Imaging

Cited by 94 publications

References 30 publications

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

Lattice‐Boltzmann modeling of contaminant degradation by chemotactic bacteria: Exploring the formation and movement of bacterial bands

Pattern Formation of Competing Microorganisms in Sediments

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