Scholarly Work - Center for Biofilm Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/9335
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Item Detachment, surface migration, and other dynamic behavior in bacterial biofilms revealed by digital time-lapse imaging(2001) Stoodley, Paul; Hall-Stoodley, Luanne; Lappin-Scott, H. M.Item Development of a standardized antibiofilm test(2001) Zelver, NickItem Characterization of extracellular chitinolytic activity in biofilms(2001) Baty, Ace M.; Diwu, Zhenjun; Dunham, G.; Eastburn, Callie C.; Geesey, Gill G.; Goodman, Amanda E.; Suci, Peter A.; Techkarnjanaruk, SomkietItem Biofilms in the new millennium: musing from a peak in Xanadu(2000) Costerton, J. WilliamItem Microbial detachment from biofilms(2000) Moore, G. F.; Dunsmore, B. C.; Jones, S. M.; Smejkal, C. W.; Jass, J.; Stoodley, Paul; Lappin-Scott, H. M.Item Modeling biocide action against biofilms(2000-03) Stewart, Philip S.; Hamilton, Martin A.; Goldstein, B. R.; Schneider, B. T.A phenomenological model of biocide action against microbial biofilms was derived. Processes incorporated in the model include bulk flow in and out of a well-mixed reactor, transport of dissolved species into the biofilm, substrate consumption by bacterial metabolism, bacterial growth, advection of cell mass within the biofilm, cell detachment from the biofilm, cell death, and biocide concentration-dependent disinfection. Simulations were performed to analyze the general behavior of the model and to perform preliminary sensitivity analysis to identify key input parameters. The model captured several general features of antimicrobial agent action against biofilms that have been observed widely by experimenters and practitioners. These included (1) rapid disinfection followed by biofilm regrowth, (2) slower detachment than disinfection, and (3) reduced susceptibility of microorganisms in biofilms. The results support the plausibility of a mechanism of biofilm resistance in which the biocide is neutralized by reaction with biofilm constituents, leading to a reduction in the bulk biocide concentration and, more significantly, biocide concentration gradients within the biofilm. Sensitivity experiments and analyses identified which input parameters influence key response variables. Each of three response variables was sensitive to each of the five input parameters, but they were most sensitive to the initial biofilm thickness and next most sensitive to the biocide disinfection rate coefficient. Statistical regression modeling produced simple equations for approximating the response variables for situations within the range of conditions covered by the sensitivity experiment. The model should be useful as a tool for studying alternative biocide control strategies. For example, the simulations suggested that a good interval between pulses of biocide is the time to minimum thickness.Item Confocal laser microscopy on biofilms: Successes and limitations(2008-07) Pitts, Betsey; Stewart, Philip S.Imaging of bacterial biofilms with microscopes has been an essential and transformative method in biofilm research. Fluorescence microscopy can elucidate specific biofilm components and cellular activities that cannot be separated otherwise. In particular, confocal fluorescence microscopy extends that examination through the thickness of a fully hydrated, in-situ biofilm, affording the potential for 3D, non-invasive, time-lapse imaging. This article discusses some striking examples of the insight provided by confocal fluorescence microscopy into biofilm structure, composition, and heterogeneity, and will also enumerate some limitations of this imaging process.Item Battling biofilms(2001-07) Costerton, J. William; Stewart, Philip S.Item Gene expression and protein levels of the stationary phase sigma factors, RpoS, in continuously-fed Pseudomonas aeruginosa biofilms(2001-05) Xu, Karen D.; Franklin, Michael J.; Park, C-H; McFeters, Gordon A.; Stewart, Philip S.Bacteria growing in biofilms experience gradients of environmental conditions, including varying levels of nutrients and oxygen. Therefore, bacteria within biofilms may enter distinct physiological states, depending on the surrounding conditions. In this study, rpoS expression and RpoS levels were measured as indicators of stationary phase growth within thick continuously-fed Pseudomonas aeruginosa biofilms. The level of rpoS expression in a 3-day-old biofilm was found to be three-fold higher than the average expression in stationary phase planktonic cultures. In planktonic cultures, oxygen limitation did not lead to increased levels of RpoS, suggesting that oxygen limitation was not the environmental signal causing increased expression of rpoS. These results suggest that bacteria within P. aeruginosa biofilms may exhibit stationary phase characteristics even when cultured in flow conditions that continually replenish nutrients.Item Bacterial behavior at surfaces(2001-06) Geesey, Gill G.Population level studies demonstrate that bacterial colonization of surfaces and subsequent biofilm architecture are controlled by a variety of factors that include the hydrodynamics, surface chemistry and genotype of the cell. New molecular tools now extend our ability to investigate among bacterial cells within a surface-associated population subtle phenotypic differences that do not involve changes in genotype. Such resolution has led to new discoveries in relationships between bacterial cells and their environment.