Microbial nanoscopy: A closer look at microbial cell surfaces

Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Croix du Sud 2/18, B-1348 Louvain-la-Neuve, Belgium.
Trends in Microbiology (Impact Factor: 9.19). 09/2010; 18(9):397-405. DOI: 10.1016/j.tim.2010.06.004
Source: PubMed


How cell envelope constituents are spatially organised and how they interact with the environment are key questions in microbiology. Unlike other bioimaging tools, atomic force microscopy (AFM) provides information about the nanoscale surface architecture of living cells and about the localization and interactions of their individual constituents. These past years have witnessed remarkable advances in our use of the AFM molecular toolbox to observe and force probe microbial cells. Recent milestones include the real-time imaging of the nanoscale organization of cell walls, the quantification of subcellular chemical heterogeneities, the mapping and functional analysis of individual cell wall constituents and the analysis of the mechanical properties of single receptors and sensors.

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    • "The development of a simple, fast and versatile platform to monitor in situ bacterial sporulation from a morphological and mechanical perspective at the nanoscale can provide key insights into this process. Atomic force microscopy (AFM) has rapidly emerged as an important, widely used tool in microbiology (Dufrene, 2008; Dupres et al., 2010; Muller & Dufrene, 2011). The unique advantage of the AFM is the ability not only to characterize cellular surfaces with nanoscale resolution and three dimensional imaging (Plomp et al., 2007), but also measure their nanomechanical forces (Dufrene & Pelling, 2013). "
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    ABSTRACT: Bacteria from the genus Bacillus are able to transform into metabolically dormant states called (endo) spores in response to nutrient deprivation and other harsh conditions. These morphologically distinct spores are fascinating constructs, amongst the most durable cells in nature, and have attracted attention owing to their relevance in food-related illnesses and bioterrorism. Observing the course of bacterial spore formation (sporulation) spatially, temporally and mechanically, from the vegetative cell to a mature spore, is critical for a better understanding of this process. Here, we present a fast and versatile strategy for monitoring both the morphological and mechanical changes of Bacillus cereus bacteria at the nanoscale using atomic force microscopy. Through a strategy of imaging and nanomechanical mapping, we show the morphogenesis of the endospore and released mature endospore. Finally, we investigate individual spores to characterize their surface mechanically. The progression in elasticity coupled with a similarity of characteristic distributions between the incipient endospores and the formed spores show these distinct stages. Taken together, our data demonstrates the power of atomic force microscopy applied in microbiology for probing this important biological process at the single cell scale. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.
    Journal of Microscopy 01/2015; DOI:10.1111/jmi.12214 · 2.33 Impact Factor
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    • "Peptidoglycan polymers are arranged to fulfil their functions on a length scale between that of these features and the subnanometer scale of muropeptide chemistry. Recently, application of techniques such as Electron Cryo Tomography (ECT) and Atomic Force Microscopy (AFM) have made molecular organization on these length scales easier to address directly (Li and Jensen, 2009; Dupres et al., 2010). "
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    ABSTRACT: Peptidoglycan performs the essential role of resisting turgor in the cell walls of most bacteria. It determines cell shape, and its biosynthesis is the target for many important antibiotics. The fundamental chemical building blocks of peptidoglycan are conserved: repeating disaccharides cross linked by peptides. However, these blocks come in many varieties and can be assembled in different ways. So beyond the fundamental similarity, prodigious chemical, organizational and architectural diversity is revealed. Here, we track the evolution of our current understanding of peptidoglycan and underpinning technical and methodological developments. The origin and function of chemical diversity is discussed with respect to some well-studied example species. We then explore how this chemistry is manifested in elegant and complex peptidoglycan organization and how this is interpreted in different and sometimes controversial architectural models. We contend that emerging technology brings about the possibility of achieving a complete understanding of peptidoglycan chemistry, through architecture, to the way in which diverse species and populations of cells meet the challenges of maintaining viability and growth within their environmental niches by exploiting the bioengineering versatility of peptidoglycan.
    Molecular Microbiology 01/2014; 91(5). DOI:10.1111/mmi.12513 · 4.42 Impact Factor
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    • "In this context atomic force microscopy (AFM) has been successfully used as analytical technique able to determine the hydrophobic/hydrophilic character of the biofilm at the nanoscale [18] [19] [20] and the tremendous advances made recently in scanning probe microscopy techniques and equipment makes it a powerful tool to study the surface characteristics of biofilm [21]. AFM is based on the detection of atomic interaction forces between a sharp tip and the sample. "
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    ABSTRACT: The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix (ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary factor affecting the balance between growth, detachment and biofilm formation, its quantification is essential in understanding, predicting, and modelling biofilm development. Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer level, the observation of the surface of living cells at high resolution, the mapping of local properties such as surface charges, the measurement of elastic properties of cell-surface constituents and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast dynamics. In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be used to obtain high-resolution topographical images and to quantify the adhesion properties of the A. fumigatus biofilm with an high acquisition rate. Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal drugs transit through the ECM.
    Applied Surface Science 04/2013; 279. DOI:10.1016/j.apsusc.2013.04.128 · 2.71 Impact Factor
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