Recent advances in mechanical characterisation of biofilm and their significance for material modelling

Böl, Markus; Ehret, Alexander E.; Albero, Antonio Bolea; Hellriegel, Jan; Krull, Rainer

doi:10.3109/07388551.2012.679250

Cited by 78 publications

(69 citation statements)

References 183 publications

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“…[52]), the exact boundary conditions often unclear and the deformations highly inhomogeneous. This renders the quantitative interpretation of experimental results and a comparison with constitutive models difficult.…”

Section: Discussionmentioning

confidence: 99%

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Modelling mechanical characteristics of microbial biofilms by network theory

Ehret

Böl

2013

J. R. Soc. Interface.

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In this contribution, we present a constitutive model to describe the mechanical behaviour of microbial biofilms based on classical approaches in the continuum theory of polymer networks. Although the model is particularly developed for the well-studied biofilms formed by mucoid Pseudomonas aeruginosa strains, it could easily be adapted to other biofilms. The basic assumption behind the model is that the network of extracellular polymeric substances can be described as a superposition of worm-like chain networks, each connected by transient junctions of a certain lifetime. Several models that were applied to biofilms previously are included in the presented approach as special cases, and for small shear strains, the governing equations are those of four parallel Maxwell elements. Rheological data given in the literature are very adequately captured by the proposed model, and the simulated response for a series of compression tests at large strains is in good qualitative agreement with reported experimental behaviour.

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Section: Discussionmentioning

confidence: 99%

“…Next, we simulate relaxation experiments, which have widely been used to characterize the viscoelastic behaviour of biofilms [52]. In the compressive mode, the biofilm is thereby rapidly compressed to a certain level and then kept at this thickness while monitoring the stress response.…”

Section: Relaxationmentioning

confidence: 99%

Modelling mechanical characteristics of microbial biofilms by network theory

Ehret

Böl

2013

J. R. Soc. Interface.

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“…Only a few studies have investigated the influence of specific matrix components on the mechanical properties of biofilms (23,24). The majority of recent studies focuses on the analysis of the mechanical properties of wild-type biofilms (25)(26)(27). These studies comprise work on biofilm elasticity (16,17,28,29), biofilm erosion stability (30), and adhesion properties (31)(32)(33), as well as theoretical investigations of mechanical biofilm characteristics (34,35).…”

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confidence: 99%

Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms

Kesel

Grumbein

Gümperlein

et al. 2016

Appl Environ Microbiol

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cMany bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed by Bacillus subtilis NCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties of B. subtilis NCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain, B. subtilis B-1, which forms biofilms containing mainly ␥-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of ␥-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties of B. subtilis biofilms. Bacteria embed themselves with secreted biopolymers (1-3), building a community that is referred to as a biofilm. Such biofilms can be formed by a variety of Gram-positive as well as Gram-negative bacteria (4). The composition of the biofilm matrix is dependent on the biofilm-forming bacterium and environmental conditions such as shear forces experienced, temperature, and nutrient availability (5); the matrix can consist of different extracellular polymeric substances (EPSs), such as polysaccharides, proteins, lipids, and nucleic acids (6). Biofilms can grow on various surfaces (7-9). While Bacillus subtilis biofilms are formed on solid nutrient surfaces or at liquid-air interfaces (10, 11), other bacteria can produce biofilms on surfaces under water-saturated conditions (in liquid) (12). Due to their high mechanical stability (13,14) and their resistance to antibiotic or chemical treatment (15-18), such biofilms present significant problems in both industry and health care (19)(20)(21)(22). Although the compositions of many biofilm matrices are known, the biomolecular reason for the outstanding resistance of bacterial biofilms is not well understood. Only a few studies have investigated the influence of specific matrix components on the mechanical properties of biofilms (23, 24). The majority of recent studies...

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“…In order to further address this issue, many clinical trials, i.e. those involving both in vivo and in vitro models, have been postulated and explored [31][32][33][34]. However, in view of the inherent features of the tongue and biofilms thereon, the precise nature of relationships between surface roughness and the nature of such biofilms remains questionable.…”

Section: Abbreviations: Ss Stainless Steelmentioning

confidence: 99%