Conceptual model for production and composition of exopolymers in biofilms

Nielsen, Per Halkjær; Jahn, Α.; Palmgren, Rikke

doi:10.1016/s0273-1223(97)00318-1

Cited by 141 publications

(9 citation statements)

References 37 publications

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“…The maximum specific growth rate calculated from the model cell yield and maximum specific substrate utilization rate was 0.08 h −1 , which is close to the reported value of 0.087-0.125 h −1 (Tang et al, 2007a;Hunt et al, 2010). The maximum specific growth rate of bacteria in biofilm is usually close to or identical to that found in suspension cultures (Characklis, 1990;Okabe et al, 1994;Nielsen et al, 1997).…”

Section: Resultssupporting

confidence: 84%

“…The ratio of bEPS to laEPS is 3:1 and EPS compose 50% of the total biomass. This is based on experimental data (Nielsen et al, 1997;Cao et al, 2011b). In our model we have the following reaction.…”

Section: Assumptions and Reactionsmentioning

confidence: 99%

“…EPS comprises 50-80% of the total organic content of a biofilm (Nielsen et al, 1997). EPS can either be tightly bound to the cell surface, called bound EPS (bEPS), or distributed in the surrounding environment of the cells in a more soluble form, called loosely associated EPS (laEPS) (Cao et al, 2011b).…”

Section: Introductionmentioning

confidence: 99%

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Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

Renslow

Ahmed

Nuñez

et al. 2017

Front. Environ. Sci.

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In this study, we developed a two-dimensional mathematical model to predict substrate utilization and metabolite production rates in Shewanella oneidensis MR-1 biofilm in the presence and absence of uranium (U). In our model, lactate and fumarate are used as the electron donor and the electron acceptor, respectively. The model includes the production of extracellular polymeric substances (EPS). The EPS bound to the cell surface and distributed in the biofilm were considered bound EPS (bEPS) and loosely associated EPS (laEPS), respectively. COMSOL ® Multiphysics finite element analysis software was used to solve the model numerically (model file provided in the Supplementary Material). The input variables of the model were the lactate, fumarate, cell, and EPS concentrations, half saturation constant for fumarate, and diffusion coefficients of the substrates and metabolites. To estimate unknown parameters and calibrate the model, we used a custom designed biofilm reactor placed inside a nuclear magnetic resonance (NMR) microimaging and spectroscopy system and measured substrate utilization and metabolite production rates. From these data we estimated the yield coefficients, maximum substrate utilization rate, half saturation constant for lactate, stoichiometric ratio of fumarate and acetate to lactate and stoichiometric ratio of succinate to fumarate. These parameters are critical to predicting the activity of biofilms and are not available in the literature. Lastly, the model was used to predict uranium immobilization in S. oneidensis MR-1 biofilms by considering reduction and adsorption processes in the cells and in the EPS. We found that the majority of immobilization was due to cells, and that EPS was less efficient at immobilizing U. Furthermore, most of the immobilization occurred within the top 10 µm of the biofilm. To the best of our knowledge, this research is one of the first biofilm immobilization mathematical models based on experimental observation. It has the ability to predict the relative contributions to U immobilization of laEPS, bEPS, and cells.

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Section: Resultssupporting

confidence: 84%

Section: Assumptions and Reactionsmentioning

confidence: 99%

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Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

Renslow

Ahmed

Nuñez

et al. 2017

Front. Environ. Sci.

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“…Although no distinct clogging layer is present on the LWA filter surface, a biofilm will establish on the filter granules. EPS that binds microorganisms together in a biofilm (Nielsen et al 1997) are made up of cell-secreted polysaccharides, proteins, lipids and nucleic acids (Flemming & Wingender 2001). These substances contain functional groups enabling both electrostatic-and hydrophobic interactions with viruses.…”

Section: Introductionmentioning

confidence: 99%

Virus removal by unsaturated wastewater filtration: effects of biofilm accumulation and hydrophobicity

Heistad

Scott

Skaarer

et al. 2009

Water Science and Technology

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Enhanced treatment of septic tank effluent can improve the hydraulic function and performance of infiltration systems and constructed wetlands. By intermittent spray application of septic tank effluent onto a coarse-grained filter media, an unsaturated flow regime beneficial for pathogen removal is created. A column filtration study showed an increase in PRD-1 removal by time of operation with corresponding biofilm accumulation in the filter material. The same increased removal was observed for 1 mum polystyrene beads, irrespective of their hydrophilic/hydrophobic surface properties. A control experiment with sorption of 1 mum hydrophobic and hydrophilic polystyrene beads to different glass surfaces with hydrophobic and hydrophilic properties indicate that mechanisms other than hydrophobic interactions may govern the rate of attachment to the filter media. For a given volumetric flow-rate in the columns, the presence of biofilm altered the hydrodynamic characteristics and this resulted in increased retention time and particle removal.

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“…Liu and Fang (2002) reported humic acids to represent 8.4–30.6 % of extracted EPS from different sludge types, whereas other studies investigating EPS from sludge and wastewater treatment sources cited lower values of 5 and 6.9 % (Frølund et al 1996; Nielsen and Jahn 1997). A study conducted with periphyton taken from an acidic river showed humic acids to only compose up to 4 % of EPS (Aguilera et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Characterization of extracellular polymeric substances (EPS) from periphyton using liquid chromatography-organic carbon detection–organic nitrogen detection (LC-OCD-OND)

Stewart

Traber

Kröll

et al. 2012

Environ Sci Pollut Res

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A protocol was developed to extract, fractionate, and quantitatively analyze periphyton extracellular polymeric substances (EPS), which obtains both information on the molecular weight (Mr) distribution and protein and polysaccharide content. The EPS were extracted from freshwater periphyton between July and December 2011. Organic carbon (OC) compounds from different EPS extracts were analyzed using liquid chromatography-organic carbon detection–organic nitrogen detection (LC-OCD-OND), and total protein and polysaccharide content were quantified. Four distinct OC fractions, on the basis of Mr, were identified in all extracts, corresponding to high Mr biopolymers (≥80–4 kDa), degradation products of humic substances (Mr not available), low Mr acids (10–0.7 kDa), and small amphiphilic/neutral compounds (3–0.5 kDa). Low C/N ratios (4.3 ± 0.8) were calculated for the biopolymer fractions, which represented 16–38 % of the measured dissolved organic carbon (DOC), indicating a significant presence of high Mr proteins in the EPS. Protein and polysaccharide represented the two major components of EPS and, when combined, accounted for the measured DOC in extracts. Differences in specific OC fractions of EPS extracts over the course of the study could be quantified using this method. This study suggests that LC-OCD-OND is a new valuable tool in EPS characterization of periphyton.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-012-1228-y) contains supplementary material, which is available to authorized users.

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Conceptual model for production and composition of exopolymers in biofilms

Cited by 141 publications

References 37 publications

Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

Virus removal by unsaturated wastewater filtration: effects of biofilm accumulation and hydrophobicity

Characterization of extracellular polymeric substances (EPS) from periphyton using liquid chromatography-organic carbon detection–organic nitrogen detection (LC-OCD-OND)

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