Biofilm formation by <scp><i>B</i></scp><i>acillus subtilis</i>: new insights into regulatory strategies and assembly mechanisms

Cairns, Lynne S.; Hobley, Laura; Stanley‐Wall, Nicola R.

doi:10.1111/mmi.12697

Cited by 205 publications

(191 citation statements)

References 89 publications

(181 reference statements)

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“…Flagella can directly sense the increased load on the motor, once a flagellum is stuck because of contact to a surface, which can lead to a 'swim-or-stick switch', resulting in the downregulation of expression of proteins needed for motility and induction of biofilm formation (reviewed in [92]). This effect has been clearly demonstrated in Caulobacter crescentus, where production of holdfasts, adhesive polysaccharides at the attached cell pole, could be visualized within minutes after attachment and flagellar arrest [10,93], and in Bacillus subtilis, where inhibition of flagellar rotation leads to biofilm formation by triggering the DegS-DegU two-component signal transduction system and other pathways [11,94,95].…”

Section: Transcriptional and Post-transcriptional Regulation Of The T3ssmentioning

confidence: 94%

Type III secretion systems: the bacterial flagellum and the injectisome

Diepold

Armitage

2015

Phil. Trans. R. Soc. B

184

175

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One contribution of 12 to a theme issue 'The bacterial cell envelope'. The flagellum and the injectisome are two of the most complex and fascinating bacterial nanomachines. At their core, they share a type III secretion system (T3SS), a transmembrane export complex that forms the extracellular appendages, the flagellar filament and the injectisome needle. Recent advances, combining structural biology, cryo-electron tomography, molecular genetics, in vivo imaging, bioinformatics and biophysics, have greatly increased our understanding of the T3SS, especially the structure of its transmembrane and cytosolic components, the transcriptional, post-transcriptional and functional regulation and the remarkable adaptivity of the system. This review aims to integrate these new findings into our current knowledge of the evolution, function, regulation and dynamics of the T3SS, and to highlight commonalities and differences between the two systems, as well as their potential applications.

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Section: Transcriptional and Post-transcriptional Regulation Of The T3ssmentioning

confidence: 94%

Type III secretion systems: the bacterial flagellum and the injectisome

Diepold

Armitage

2015

Phil. Trans. R. Soc. B

184

175

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“…The biofilm matrix largely consists of proteins, polysaccharides, and DNA. It provides a source of water and nutrients, and confers structural integrity (1)(2)(3)(4). Biofilms formed by the Gram-positive bacterium Bacillus subtilis are characterized by a highly wrinkled morphology and a hydrophobic surface.…”

mentioning

confidence: 99%

Interfacial self-assembly of a bacterial hydrophobin

Bromley

Morris

Hobley

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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132

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The majority of bacteria in the natural environment live within the confines of a biofilm. The Gram-positive bacterium Bacillus subtilis forms biofilms that exhibit a characteristic wrinkled morphology and a highly hydrophobic surface. A critical component in generating these properties is the protein BslA, which forms a coat across the surface of the sessile community. We recently reported the structure of BslA, and noted the presence of a large surfaceexposed hydrophobic patch. Such surface patches are also observed in the class of surface-active proteins known as hydrophobins, and are thought to mediate their interfacial activity. However, although functionally related to the hydrophobins, BslA shares no sequence nor structural similarity, and here we show that the mechanism of action is also distinct. Specifically, our results suggest that the amino acids making up the large, surface-exposed hydrophobic cap in the crystal structure are shielded in aqueous solution by adopting a random coil conformation, enabling the protein to be soluble and monomeric. At an interface, these cap residues refold, inserting the hydrophobic side chains into the air or oil phase and forming a three-stranded β-sheet. This form then self-assembles into a wellordered 2D rectangular lattice that stabilizes the interface. By replacing a hydrophobic leucine in the center of the cap with a positively charged lysine, we changed the energetics of adsorption and disrupted the formation of the 2D lattice. This limited structural metamorphosis represents a previously unidentified environmentally responsive mechanism for interfacial stabilization by proteins.BslA | interfacial self-assembly | bacterial hydrophobin | Bacillus subtilis | biofilm

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“…Biofilms can grow on various surfaces (7)(8)(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)(16)(17)(18), such biofilms present significant problems in both industry and health care (19)(20)(21)(22).…”

mentioning

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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Biofilm formation by Bacillus subtilis: new insights into regulatory strategies and assembly mechanisms

Cited by 205 publications

References 89 publications

Type III secretion systems: the bacterial flagellum and the injectisome

Type III secretion systems: the bacterial flagellum and the injectisome

Interfacial self-assembly of a bacterial hydrophobin

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

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