Microbial Surfaces Investigated Using Atomic Force Microscopy

Bol’shakova, A. V.; Kiselyova, Olga I.; Яминский, И.В.

doi:10.1021/bp049742c

Cited by 81 publications

(70 citation statements)

References 42 publications

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“…For AFM analysis, the treated cells were applied on a freshly cleaved mica surface and allowed to dry before imaging (9,29). To determine the effect of the treatments on the cell membrane, an average of four images on different areas for each sample were imaged.…”

Section: Methodsmentioning

confidence: 99%

Weakening Effect of Cell Permeabilizers on Gram-Negative Bacteria Causing Biodeterioration

Alakomi

Paananen

Suihko

et al. 2006

Appl Environ Microbiol

120

104

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Gram-negative bacteria play an important role in the formation and stabilization of biofilm structures on stone surfaces. Therefore, the control of growth of gram-negative bacteria offers a way to diminish biodeterioration of stone materials. The effect of potential permeabilizers on the outer membrane (OM) properties of gram-negative bacteria was investigated and further characterized. In addition, efficacy of the agents in enhancing the activity of a biocide (benzalkonium chloride) was assessed. EDTA, polyethylenimine (PEI), and succimer (meso-2,3-dimercaptosuccinic) were shown to be efficient permeabilizers of the members of Pseudomonas and Stenotrophomonas genera, as indicated by an increase in the uptake of a hydrophobic probe (1-N-phenylnaphthylamine) and sensitization to hydrophobic antibiotics. Visualization of Pseudomonas cells treated with EDTA or PEI by atomic force microscopy revealed damage in the outer membrane structure. PEI especially increased the surface area and bulges of the cells. Topographic images of EDTA-treated cells were compatible with events assigned for the effect of EDTA on outer membranes, i.e., release of lipopolysaccharide and disintegration of OM structure. In addition, the effect of EDTA treatment was visualized in phase-contrast images as large areas with varying hydrophilicity on cell surfaces. In liquid culture tests, EDTA and PEI supplementation enhanced the activity of benzalkonium chloride toward the target strains. Use of permeabilizers in biocide formulations would enable the use of decreased concentrations of the active biocide ingredient, thereby providing environmentally friendlier products.

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Section: Methodsmentioning

confidence: 99%

Weakening Effect of Cell Permeabilizers on Gram-Negative Bacteria Causing Biodeterioration

Alakomi

Paananen

Suihko

et al. 2006

Appl Environ Microbiol

120

104

View full text Add to dashboard Cite

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“…Cell surface hydrophobicity and charge have also been investigated using chemically functionalized AFM probes (2, 41). All of these studies and measurements provide important information on single-cell properties; nevertheless, they do not provide information on the properties of whole biofilms.Because of the difficulties associated with working with biofilms, particularly their softness and gelatinous nature, most biofilms imaged by AFM have been dried first (8,25,35). Drying is expected to significantly change the strength and…”

mentioning

confidence: 99%

“…Because of the difficulties associated with working with biofilms, particularly their softness and gelatinous nature, most biofilms imaged by AFM have been dried first (8,25,35). Drying is expected to significantly change the strength and…”

mentioning

confidence: 99%

Biofilm Cohesiveness Measurement Using a Novel Atomic Force Microscopy Methodology

Ahimou¹,

Semmens²,

Novak³

et al. 2007

Appl Environ Microbiol

113

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Biofilms can be undesirable, as in those covering medical implants, and beneficial, such as when they are used for waste treatment. Because cohesive strength is a primary factor affecting the balance between growth and detachment, its quantification is essential in understanding, predicting, and modeling biofilm development. In this study, we developed a novel atomic force microscopy (AFM) method for reproducibly measuring, in situ, the cohesive energy levels of moist 1-day biofilms. The biofilm was grown from an undefined mixed culture taken from activated sludge. The volume of biofilm displaced and the corresponding frictional energy dissipated were determined as a function of biofilm depth, resulting in the calculation of the cohesive energy. Our results showed that cohesive energy increased with biofilm depth, from 0.10 ؎ 0.07 nJ/m 3 to 2.05 ؎ 0.62 nJ/m 3 . This observation was reproducible, with four different biofilms showing the same behavior. Cohesive energy also increased from 0.10 ؎ 0.07 nJ/m 3 to 1.98 ؎ 0.34 nJ/m 3 when calcium (10 mM) was added to the reactor during biofilm cultivation. These results agree with previous reports on calcium increasing the cohesiveness of biofilms. This AFM-based technique can be performed with available off-the-shelf instrumentation. It could therefore be widely used to examine biofilm cohesion under a variety of conditions.It is essential to understand biofilm stability to both encourage biofilm maintenance in some applications, such as waste treatment, and effectively remove undesired biofilm in others, as in biofilms covering medical implants. Biofilm detachment is one of the critical factors that balance growth and plays a role in the development of biofilm spatial heterogeneity. While factors responsible for biofilm growth are well studied (16,29,39,42,43), those controlling the detachment process are not clearly understood (28,36,38). As a consequence, a good understanding of the relationships between operating conditions and biofilm cohesion is lacking. The cohesive strength of the biofilm is influenced by extracellular polymeric substances (EPS) and specific compounds, such as calcium, which fill the space between microbial cells and bind cells together (23,30). Understanding the cohesive interactions in the biofilm matrix under a variety of conditions could lead to the design of new strategies for controlling biofilm development based on disrupting or protecting the matrix holding the biofilm together.Because cohesive strength is a primary factor affecting biofilm sloughing, its quantification is essential in understanding detachment. A few methods based on the use of custom devices have been proposed to investigate biofilm cohesive strength. Poppele and Hozalski (31) measured the tensile strength levels of biofilms from activated sludge by using a micromechanical device based on the deflection of a glass micropipette separating a microbial aggregate held by suction. Körstgens et al. (22) used a uniaxial compression measurement device to determine the yield st...

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“…[1][2][3][4][5][6][7] The atomic force microscopy (AFM) was invented in 1986 8 , and since then, it has been used to image stainless steel 9-13 as well as bacterial cells. [14][15][16][17][18] To generate images using AFM, a cantilever is rastered over a surface, and the change in location of a reflected laser focused on the top of the cantilever is used to monitor the surface topography of the sample. Compared to other imaging methods such as confocal scanning laser microscopy or scanning electron microscopy, the advantage to imaging with AFM is that the visualization of bacterial biofilms can be performed without extensive preparation of the sample.…”

Section: Introductionmentioning

confidence: 99%

Effects of Contact Time, Pressure, Percent Relative Humidity (%RH), and Material Type on Listeria Biofilm Adhesive Strength at a Cellular Level Using Atomic Force Microscopy (AFM)

Rodrı́guez

Autio²,

McLandsborough

2008

Food Biophysics

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Whereas the transfer of Listeria from surfaces to foods and vice versa has been well documented, little is known about the mechanism of bacterial transfer. The objective of this work is to gain a better understanding of the forces involved in listerial biofilms adhesion using atomic force microscopy (AFM). L. monocytogenes Scott A was grown as biofilms on stainless steel surfaces by inoculating stainless steel coupons with Listeria and incubating the coupons for 48 h at 32°C with a diluted 1:20 tryptic soy broth. After growth, biofilms were equilibrated over saturated salt solutions at a constant relative humidity (%RH) before measurement of adhesion forces using AFM. The effects of contact time, loading force, and biofilm relative humidity (%RH) suggested that neither contact time, loading force nor biofilm %RH had a significant effect on biofilm adhesiveness at a cellular level (P>0.05). In a second set of experiments, the influence of material type on biofilm adhesiveness was evaluated using two different colloidal probes (SiO 2 and polyethylene). Results showed that the maximum pull-off force and retraction work needed to retract the cantilever for glass (−85.42 nN and 1.610 −15 J, respectively) were significantly lower than those of polyethylene (−113.38 nN and 2.7× 10 -15 J, respectively; P<0.001). The results of this study suggest that Listeria biofilms adhere more strongly to hydrophobic surfaces than hydrophilic surfaces when measured at a cellular level. These results provide important insights that could lead to new ways to remediate and avoid listerial biofilm formation in the food industry.

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Microbial Surfaces Investigated Using Atomic Force Microscopy

Cited by 81 publications

References 42 publications

Weakening Effect of Cell Permeabilizers on Gram-Negative Bacteria Causing Biodeterioration

Weakening Effect of Cell Permeabilizers on Gram-Negative Bacteria Causing Biodeterioration

Biofilm Cohesiveness Measurement Using a Novel Atomic Force Microscopy Methodology

Effects of Contact Time, Pressure, Percent Relative Humidity (%RH), and Material Type on Listeria Biofilm Adhesive Strength at a Cellular Level Using Atomic Force Microscopy (AFM)

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