Center for Biofilm Engineering (CBE)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/9334
At the Center for Biofilm Engineering (CBE), multidisciplinary research teams develop beneficial uses for microbial biofilms and find solutions to industrially relevant biofilm problems. The CBE was established at Montana State University, Bozeman, in 1990 as a National Science Foundation Engineering Research Center. As part of the MSU College of Engineering, the CBE gives students a chance to get a head start on their careers by working on research teams led by world-recognized leaders in the biofilm field.
Browse
18 results
Search Results
Item Quantifying NMR relaxation correlation and exchange in articular cartilage with time domain analysis(2018-02) Mailhiot, Sarah E.; Zong, Fangrong; Maneval, James E.; Galvosas, Petrik; Seymour, Joseph D.Measured nuclear magnetic resonance (NMR) transverse relaxation data in articular cartilage has been shown to be multi-exponential and correlated to the health of the tissue. The observed relaxation rates are dependent on experimental parameters such as solvent, data acquisition methods, data analysis methods, and alignment to the magnetic field. In this study, we show that diffusive exchange occurs in porcine articular cartilage and impacts the observed relaxation rates in T1-T2 correlation experiments. By using time domain analysis of T2-T2 exchange spectroscopy, the diffusive exchange time can be quantified by measurements that use a single mixing time. Measured characteristic times for exchange are commensurate with T1 in this material and so impacts the observed T1 behavior. The approach used here allows for reliable quantification of NMR relaxation behavior in cartilage in the presence of diffusive fluid exchange between two environments.Item NMR investigation of water diffusion in different biofilm structures(2017-09) Herrling, M. P.; Weisbrodt, Jessica; Kirkland, Catherine M.; Williamson, Nathan H.; Lackner, S.; Codd, Sarah L.; Seymour, Joseph D.; Guthausen, G.; Horn, H.Mass transfer in biofilms is determined by diffusion. Different mostly invasive approaches have been used to measure diffusion coefficients in biofilms, however, data on heterogeneous biomass under realistic conditions is still missing. To non-invasively elucidate fluid–structure interactions in complex multispecies biofilms pulsed field gradient-nuclear magnetic resonance (PFG-NMR) was applied to measure the water diffusion in five different types of biomass aggregates: one type of sludge flocs, two types of biofilm, and two types of granules. Data analysis is an important issue when measuring heterogeneous systems and is shown to significantly influence the interpretation and understanding of water diffusion. With respect to numerical reproducibility and physico-chemical interpretation, different data processing methods were explored: (bi)-exponential data analysis and the Γ distribution model. Furthermore, the diffusion coefficient distribution in relation to relaxation was studied by D-T2 maps obtained by 2D inverse Laplace transform (2D ILT). The results show that the effective diffusion coefficients for all biofilm samples ranged from 0.36 to 0.96 relative to that of water. NMR diffusion was linked to biofilm structure (e.g., biomass density, organic and inorganic matter) as observed by magnetic resonance imaging and to traditional biofilm parameters: diffusion was most restricted in granules with compact structures, and fast diffusion was found in heterotrophic biofilms with fluffy structures. The effective diffusion coefficients in the biomass were found to be broadly distributed because of internal biomass heterogeneities, such as gas bubbles, precipitates, and locally changing biofilm densities. Thus, estimations based on biofilm bulk properties in multispecies systems can be overestimated and mean diffusion coefficients might not be sufficiently informative to describe mass transport in biofilms and the near bulk.Item Peclet number dependent superdiffusive hydrodynamic dispersion in a site percolation porous media measured by NMR(2017-04) Seymour, Joseph D.; Codd, Sarah L.; Kimmich, RainerThe displacement time dependent hydrodynamic dispersion in a model 2D site percolation structure is measured using PGSE NMR. The data indicate superdiffusive scaling of the mean squared displacement at high Peclet numbers, where advective transport dominates, consistent with classic percolation scaling concepts. The time scaling of the mean squared displacement is shown to vary with the Peclet number demonstrating a dependence on the changing dynamics.Item Anomalous fluid transport in porous media induced by biofilm growth(2004-11) Seymour, Joseph D.; Gage, Justin P.; Codd, Sarah L.; Gerlach, RobinMagnetic resonance measurements of the transition from normal to anomalous hydrodynamic dispersion in porous media due to biological activity are presented. Fractional advection-diffusion equations are shown to provide models for the measured impact of biofilm growth on porous media transport dynamics.Item Magnetic resonance microscopy of biofilm structure and impact on transport in a capillary bioreactor(2004-04) Seymour, Joseph D.; Codd, Sarah L.; Gjersing, Erica L.; Stewart, Philip S.Microorganisms that colonize surfaces, biofilms, are of significant importance due to their role in medical infections, subsurface contaminant remediation, and industrial processing. Spatially resolved data on the distribution of biomass within a capillary bioreactor, the heterogeneity of the biofilm itself and the impact on transport dynamics for a Staphylococcus epidermidis biofilm in the natural growth state are presented. The data demonstrate the ability of magnetic resonance microscopy to study spatially resolved processes in bacterial biofilms, thus providing a basis for future studies of spatially resolved metabolism and in vivo clinical detection.Item Magnetic resonance microscopy analysis of advective transport in a biofilm reactor(2005) Gjersing, Erica L.; Codd, Sarah L.; Seymour, Joseph D.; Stewart, Philip S.In this article we present magnetic resonance microscopy (MRM) characterization of the advective transport in a biofilm capillary reactor. The biofilm generates non-axial flows that are up to 20% of the maximum axial velocity. The presence of secondary velocities of this magnitude alters the mass transport in the bioreactor relative to non-biofilm fouled reactors and questions the applicability of empirical mass transfer coefficient approaches. The data are discussed in the context of simulations and models of biofilm transport and conceptual aspects of transport modeling in complex flows are also discussed. The variation in the residence time distribution due to biofilm growth is calculated from the measured propagator of the motion. Dynamical systems methods applied to model fluid mixing in complex flows are indicated as a template for extending mass transport theory to quantitatively incorporate microscale data on the advection field into macroscale mass transfer models.Item Magnetic resonance microscopy of biofilm and bioreactor transport(2006-02) Codd, Sarah L.; Seymour, Joseph D.; Gjersing, Erica L.; Gage, Justin P.; Brown, Jennifer R.Item Magnetic resonance microscopy of biofouling induced scale dependent transport in porous media(2007-06) Seymour, Joseph D.; Gage, Justin P.; Codd, Sarah L.; Gerlach, RobinNon-invasive magnetic resonance microscopy (MRM) methods are applied to study biofouling of a homogeneous model porous media. MRM of the biofilm biomass using magnetic relaxation weighting shows the heterogeneous nature of the spatial distribution of the biomass as a function of growth. Spatially resolved MRM velocity maps indicate a strong variation in the pore scale velocity as a function of biofilm growth. The hydrodynamic dispersion dynamics for flow through the porous media is quantitatively characterized using a pulsed gradient spin echo technique to measure the propagator of the motion. The propagator indicates a transition in transport dynamics from a Gaussian normal diffusion process following a normal advection diffusion equation to anomalous transport as a function of biofilm growth. Continuous time random walk models resulting in a time fractional advection diffusion equation are shown to model the transition from normal to anomalous transport in the context of a conceptual model for the biofouling. The initially homogeneous porous media is transformed into a more complex heterogeneous porous media by the biofilm growth.Item T2 –T2 exchange in biofouled porous media(2009) Hornemann, Jennifer A.; Codd, Sarah L.; Romanenko, K. R.; Seymour, Joseph D.Recent two dimensional nuclear magnetic resonance (NMR) techniques access exchange in pore structures through surface relaxation and diffusion based relaxation [1-4]. This research applies these techniques to measure pore changes due to biofilm growth and the impact this growth has on diffusion transport. The porous media used in this study are model beadpacks constructed from borosilicate glass beads with diameters approximately 100 μm. This research shows that through changes in the relaxation rates, NMR can be used to verify biofilm growth in porous media.Item Biopolymer and water dynamics in microbial biofilm extracellular polymeric substance(2008-09) Hornemann, Jennifer A.; Lysova, Anna A.; Codd, Sarah L.; Seymour, Joseph D.; Busse, S.; Stewart, Philip S.; Brown, Jennifer R.Nuclear magnetic resonance (NMR) is a noninvasive and nondestructive tool able to access several observable quantities in biofilms such as chemical composition, diffusion, and macroscale structure and transport. Pulsed gradient spin echo (PGSE) NMR techniques were used to measure spectrally resolved biomacromolecular diffusion in biofilm biomass, extending previous research on spectrally resolved diffusion in biofilms. The dominant free water signal was nulled using an inversion recovery modification of the traditional PGSE technique in which the signal from free water is minimized in order to view the spectra of components such as the rotationally mobile carbohydrates, DNA, and proteins. Diffusion data for the major constituents obtained from each of these spectral peaks demonstrate that the biomass of the biofilm contains both a fast and slow diffusion component. The dependence of diffusion on antimicrobial and environmental challenges suggests the polymer molecular dynamics measured by NMR are a sensitive indicator of biofilm function.