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.
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Item Biofouling and corrosion of stainless steels in natural waters(2002) Lewandowski, Zbigniew; Avci, Recep; Geiser, Michael Joseph; Braughton, K. R.; Yurt, NurdanThe noble shift in corrosion potential to values between +300 and +400 mVSCE and the accompanying increase in cathodic current density and polarization slope at mild cathodic potentials that develop during microbial colonization of passive metals, are collectively known as ennoblement. This phenomenon is of concern as the noble shift in the corrosion potential may lead to pitting corrosion. We have demonstrated, by growing pure cultures of manganese oxidizing bacteria (MOB) Leptothrix discophora SP-6 under well defined conditions, that microbial deposition of manganese oxides causes ennoblement of 316L stainless steel (SS). Exposing 316L corrosion coupons in lakes and streams supported this conclusion; the rate and extent of ennoblement were positively correlated with the rates of deposition and the amounts of biomineralized manganese oxides deposited on the surfaces of the SS corrosion coupons. X-ray photoelectron spectroscopy (XPS) analyses of the deposits from the ennobled coupons revealed a mixture of manganese oxides, as expected. Many natural waters can support growth of MOB. When manganese-oxidizing biofilms accumulate on surfaces of passive metals there is a potential for manganese redox cycling on the metal surface. This process is initiated by depositing minute amounts of manganese oxides on the metal surface. These microbially deposited manganese oxides are then reduced by the electrons derived from anodic dissolution of the metal; the metal is corroding and the manganese oxides are reduced to divalent manganese ions. However, since the manganese ions are liberated within the manganese-oxidizing biofilm, the manganese ions are immediately reoxidized, and the cycle continues.Item Manganese dioxide as a potential cathodic reactant in corrosion of stainless steels(2000) Olesen, Bo H.; Avci, Recep; Lewandowski, ZbigniewBiofilms of leptothrix discophora SP-6, grown on 316L stainless steel (SS), ennobled the open circuit potential to 410 mVSCE. X-ray Photoelectron Spectroscopy (XPS) identified MnO2 was studied using electroplated SS. Plated MnO2 was reduced amperometrically. The process was interrupted at different reduction stages. XPS analysis of remaining oxides showed that MnO2 was reduced through MnOOH to Mn2+. We conclude that biomineralized MnO2 may increase corrosion rates by serving as a cathodic reactant.Item Magnetic resonance analysis of capillary formation reaction front dynamics in alginate gels(2011-09) Maneval, James E.; Bernin, D.; Fabich, H. T.; Seymour, Joseph D.; Codd, Sarah L.The formation of heterogeneous structures in biopolymer gels is of current interest for biomedical applications and is of fundamental interest to understanding the molecular level origins of structures generated from disordered solutions by reactions. The cation-mediated physical gelation of alginate by calcium and copper is analyzed using magnetic resonance measurements of spatially resolved molecular dynamics during gel front propagation. Relaxation time and pulse-field gradient methods are applied to determine the impact of ion front motion on molecular translational dynamics. The formation of capillaries in alginate copper gels is correlated to changes in translational dynamics.Item Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system(2011-04) Khan, Mohiuddin M. T.; Takizawa, S.; Lewandowski, Zbigniew; Jones, Warren L.; Camper, Anne K.; Katayama, H.; Ohgaki, S.To quantify the effect of dynamic particle size changes and degradation and accumulation of suspended solids (SS) in influents to reactors on membrane fouling frequency in hybrid powder-activated carbon (PAC)–microfiltration (MF) reactors, we operated a PAC–MF system (hollow-fiber module) for more than five months to purify river water before and after pretreatment by a biofilter. The transmembrane pressure, backwashing pressure, resistance to filtration, and SS accumulation and degradation during these dynamic changes were evaluated. The initial dose of PAC was 40 g/L of the reactor and no additional PAC was added during this continuous operational period. The presence of PAC reduced the membrane resistance to filtration even at the end of filtration period when the number of particles in the smallest range (>1.0–3.6 μm) was the highest measured by the flow cytometer and microscopy image analysis. This resistance was reduced further when the river water was biofiltered prior to membrane filtration. This real-time study demonstrates that over time PAC and other particles coming into the reactors through the influents degrade and/or become smaller because of the turbulence caused by continuous aeration below the MF membrane fibers. The number of particles in the reactors with diameters less than 10 μm increased with time, increasing the fouling frequency; however, the presence of PAC further reduced the particle enhanced fouling. The presence of PAC also increased SS degradation by up to 10%. The increased number of bacteria inside the PAC–MF systems did not contribute to the number of membrane fouling. Even though the particle sizes inside the reactors became smaller with time, the gradual increase in net accumulation of SS was also an important factor controlling the performance of the PAC–MF system.Item Resolution of volatile fuel compound profiles from Ascocoryne sarcoides: A comparison by proton transfer reaction-mass spectrometry and solid phase microextraction gas chromatography mass spectrometry(2012-04) Mallette, Natasha D.; Knighton, W. Berk; Strobel, Gary A.; Carlson, Ross P.; Peyton, Brent M.Volatile hydrocarbon production by Ascocoryne sacroides was studied over its growth cycle. Gas-phase compounds were measured continuously with a proton transfer reaction-mass spectrometry (PTR-MS) and at distinct time points with gas chromatography-mass spectrometry (GC-MS) using head space solid phase microextraction (SPME). The PTR-MS ion signal permitted temporal resolution of the volatile production while the SPME results revealed distinct compound identities. The quantitative PTR-MS results showed the volatile production was dominated by ethanol and acetaldehyde, while the concentration of the remainder of volatiles consistently reached 2,000 ppbv. The measurement of alcohols from the fungal culture by the two techniques correlated well. Notable compounds of fuel interest included nonanal, 1-octen-3-ol, 1-butanol, 3-methyl- and benzaldehyde. Abiotic comparison of the two techniques demonstrated SPME fiber bias toward higher molecular weight compounds, making quantitative efforts with SPME impractical. Together, PTR-MS and SPME GC-MS were shown as valuable tools for characterizing volatile fuel compound production from microbiological sources.Item Nuclear magnetic resonance measurement of hydrodynamic dispersion in porous media: Preasymptotic dynamics, structure and nonequilibrium statistical mechanics(2012-10) Codd, Sarah L.; Seymour, Joseph D.Measurement of displacement time and length scale dependent dynamics by pulsed gradient spin echo nuclear magnetic resonance in porous media directly provides the preasymptotic hydrodynamic dispersion coefficient. This allows for comparison with nonequilibrium statistical mechanics models of hydrodynamics dispersion in porous media. Preasymptotic dispersion data and models provide characterization of porous media structure length scales relevant to transport and are related to the permeability and sample heterogeneity.Item Comparison of single and joint effects of Zn and Cu in continuous flow and batch reactors(2012-03) Sengor, S. S.; Gikas, P.; Moberly, James G.; Peyton, Brent M.; Ginn, Timothy R.BACKGROUND: Microbial behavior in batch reactors may be different from that in continuous flow reactors, which is expected to affect microbial response to heavy metal exposure. Four parallel continuous flow reactors and batch growth tests were used to investigate the single and joint toxicity of Zn and Cu to Artrobacter sp. JM018.RESULTS: The results indicated that Cu is more toxic than Zn under all conditions. In the batch reactors, all Zn concentrations showed a stimulatory effect on microbial growth. However in the continuous system, 125 µmol L−1 Zn exposure produced inhibition. In the case of mixed Zn and Cu exposures in the batch system, the presence of Zn reduced the severity of Cu inhibition, with a net impact of reduced growth in all cases, whereas in the continuous system microbial growth and substrate utilization rates sharply decreased and ceased.CONCLUSION: The results clearly showed that growth in batch reactors underestimated significantly the heavy metal inhibition, compared with the continuous system. Therefore, the results of batch reactor tests should not be used directly when heavy metal inhibition is to be interpreted for continuous flow systems.Item Kinetic theories for biofilms(2012-01) Wang, Qi; Zhang, Tian-YuWe apply the kinetic theory formulation for binary complex fluids to develop a set of hydrodynamic models for the two-phase mixture of biofilms and solvent (water). It is aimed to model nonlinear growth and transport of the biomass in the mixture and the biomass-flow interaction. In the kinetic theory formulation of binary complex fluids, the biomass consisting of EPS (Extracellular Polymeric Substance) polymer networks and bacteria is coarse-grained into an effective fluid component, termed the effective polymer solution; while the other component, termed the effective solvent, is made up of the ensemble of nutrient substrates and the solvent. The mixture is modeled as an incompressible two-phase fluid in which the presence of the effective components are quantified by their respective volume fractions. The kinetic theory framework allows the incorporation of microscopic details of the biomass and its interaction with the coexisting effective solvent. The relative motion of the biomass and the solvent relative to an average velocity is described by binary mixing kinetics along with the intrinsic molecular elasticity of the EPS network strand modeled as an elastic dumbbell. This theory is valid in both the biofilm region which consists of the mixture of the biomass and solvent and the pure solvent region, making it convenient in numerical simulations of the biomass-flow interaction. Steady states and their stability are discussed under a growth condition. Nonlinear solutions of the three models developed in this study in simple shear are calculated and compared numerically in 1-D space.Item Biofilm detection in natural unconsolidated porous media using a low-field magnetic resonance system(2013-04) Sanderlin, A. B.; Vogt, Sarah J.; Grunewald, E.; Bergin, B. A.; Codd, Sarah L.The extent to which T2 relaxation measurements can be used to determine biofouling in several natural geological sand media using a low-field (275 kHz, 6.5 mT) NMR system has been demonstrated. It has been previously shown that, at high laboratory strength fields (300 MHz, 7 T), T2 techniques can be used as a bioassay to confirm the growth of biofilm inside opaque porous media with low magnetic susceptibilities such as borosilicate or soda lime glass beads. Additionally decreases in T2 can be associated with intact biofilm as opposed to degraded biofilm material. However, in natural geological media, the strong susceptibility gradients generated at high fields dominated the T2 relaxation time distributions and biofilm growth could not be reliably detected. Samples studied included Bacillus mojavensis biofilm in several sand types, as well as alginate solution and alginate gel in several sand types. One of the sand types was highly magnetic. Data was collected with a low-field (275 kHz, 6.5 mT) benchtop NMR system using a CPMG sequence with an echo time of 1.25 ms providing the ability to detect signals with T2 greater than 1 ms. Data presented here clearly demonstrate that biofilm can be reliably detected and monitored in highly magnetically susceptible geological samples using a low-field NMR spectrometer indicating that low-field NMR could be viable as a biofilm sensor at bioremedation sites.Item Krylov space approximate Kalman filtering(2013-03) Bardsley, Johnathan M.; Parker, Albert E.; Solonen, Antti; Howard, MarylesaThe Kalman filter is a technique for estimating a time-varying state given a dynamical model for and indirect measurements of the state. It is used, for example, on the control problems associated with a variety of navigation systems. Even in the case of nonlinear state and/or measurement models, standard implementations require only linear algebra. However, for sufficiently large-scale problems, such as arise in weather forecasting and oceanography, the matrix inversion and storage requirements of the Kalman filter are prohibitive, and hence, approximations must be made. In this paper, we describe how the conjugate gradient iteration can be used within the Kalman filter for quadratic minimization, as well as for obtaining low-rank approximations of the covariance and inverse-covariance matrices required for its implementation. The approach requires that we exploit the connection between the conjugate gradient and Lanczos iterations.