Sausage Casings as a Model for Attachment of Salmonella to Meat

1993 ◽  
Vol 56 (5) ◽  
pp. 390-394 ◽  
Author(s):  
ISABEL WALLS ◽  
PETER H. COOKE ◽  
ROBERT C. BENEDICT ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Attachment ◽  
Bacterial Cells ◽  
Inoculum Level ◽  
Plate Counts ◽  
Increasing Temperature ◽  
Convenient Model ◽  
Sausage Casing ◽  
Scanning Electron

Artificial sausage casings were used as a model for studying bacterial attachment to meat connective tissue. Sausage casings of known mass were exposed to suspensions of Salmonella typhimurium in 0.15 M NaCl under various time, temperature, and inoculum level regimes, then washed to remove unattached bacteria. Attached bacterial cells were enumerated using both plate counts and scanning electron microscopy. Bacterial cells attached to sausage casing surfaces within 1 min of incubation. Numbers of attached cells increased with increasing temperature and inoculum levels and with time. Rates of attachment of S. typhimurium to sausage casings were comparable with those reported for attachment to meat surfaces. Sausage casings appear to be a convenient model for examining mechanisms of bacterial attachment to meats.

Influence of Three Defeathering Systems on Microtopography of Turkey Skin and Adhesion of Salmonella typhimurium

1993 ◽  
Vol 56 (4) ◽  
pp. 286-291 ◽  
Author(s):  
JEONG-WEON KIM ◽  
STEPHANIE DOORES
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salmonella Typhimurium ◽  
Indirect Measurement ◽  
Bacterial Attachment ◽  
Deep Penetration ◽  
Attachment Strength ◽  
Plate Counts ◽  
Strong Attachment ◽  
Scanning Electron

The microtopography of turkey skin resulting from three different defeathering systems and consequent effect of skin microtopography on the adhesion of Salmonella typhimurium were examined. Turkeys from common flocks were scalded and picked using conventional, kosher, and steam-spray systems. Breast skin was subsequently removed, irradiated to eliminate the resident microflora, then inoculated with S. typhimurium for 30 min. Scanning electron microscopy (SEM) and light microscopy revealed that three processes caused different skin microtopographies, which resulted in different amounts of bacterial adhesion. Conventional skin had a comparatively smoother surface and less bacterial attachment. Kosher skin was very rough with a scaly keratinized epidermis and showed little bacterial attachment. Steam-spray skin had a highly convoluted surface (probably with underlying collagen fiber bundles) and showed three times higher attachment of cells than conventional and kosher skins. Contrary to counts of attached cells obtained by scanning electron microscopy, plate counts of all inoculated skins were similar and increased linearly with increasing inoculum concentration. The highest Sm value (an indirect measurement of attachment strength) of kosher skin reflected deep penetration/entrapment of cells within the skin rather than strong attachment of cells, whereas the high Sm value of steam-spray skin would reflect the strong attachment of cells to the specific receptors in the skin. The lowest Sm value and much bigger cell size of S. typhimurium on conventional skin reflected loose bacterial attachment and different surface properties, respectively.

Influence of Titanium Alloying Element Substrata on Bacterial Adhesion

2012 ◽  
Vol 535-537 ◽  
pp. 992-995
Author(s):  
Kun Mediaswanti ◽  
Vi Khanh Truong ◽  
Jafar Hasan ◽  
Elena P. Ivanova ◽  
Francois Malherbe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Staphylococcus Aureus ◽  
Bacterial Adhesion ◽  
Infection Risk ◽  
Bacterial Attachment ◽  
Bacterial Strains ◽  
Alloying Element ◽  
Bacteria Adhesion ◽  
Scanning Electron

Titanium and titanium alloys have been widely employed in many load-bearing orthopaedic applications due to their excellent strength and corrosion resistance. However, postimplantation infections might occur even though considerable studies have been made. Choosing a bio-friendly alloying element is one way to reduce infection risk. The aim of this study is to evaluate the extent of bacterial attachment on titanium, tantalum, niobium and tin surfaces. Two pathogenic bacterial strains, namely Staphylococcus aureus CIP 65.8T and Pseudomonas aeruginosa ATCC 9027, were used in this study. Quantification of bacterial attachment was performed using scanning electron microscopy. Results indicated that the surface chemistry and topography of the investigated materials significantly influence the degree of P. aeruginosa and S. aureus adhesion; however, surface wettability did not show a significant impact upon bacterial retention. In this study, tin was shown to be the most attractive material for bacteria adhesion but tantalum limits the bacterial adhesion. Therefore, it is suggested to limit the amount of tin as an titanium alloying element due to its nature to attract P. aeruginosa and S. aureus adhesion.

Thermal Conductivity of Boron Carbides

1987 ◽  
Vol 97 ◽  
Author(s):  
Marvin Moss
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Temperature Dependence ◽  
Rutherford Backscattering ◽  
Rutherford Backscattering Spectroscopy ◽  
Theoretical Density ◽  
Increasing Temperature ◽  
Scanning Electron

ABSTRACTThe thermal conductivity, k, of boron carbides of various B/C ratios, two modes of preparation – hot pressed and carbothermic, and two isotopic variants of boron – 11B and normal boron 10.81B, was measured from 300 to 1023 K. The density and composition of the samples were reflected in the magnitude and temperature dependence of k, and were investigated further with scanning electron microscopy, Rutherford backscattering spectroscopy, and Raman spectroscopy. While lower than theoretical density in B4C reduces k, the characteristic monotonic decline of k with increasing temperature is retained. This k-vs.-T behavior distinguishes B4C from material with larger B/C ratios for which the temperature dependence is essentially nil.

Scanning electron microscopy of mouse ciliated oviduct and tracheal epithelium infected in vitro with Bordetella pertussis

1983 ◽  
Vol 29 (4) ◽  
pp. 415-420 ◽  
Author(s):  
Lauren B. Opremcak ◽  
Melvin S. Rheins
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Organ Culture ◽  
Bordetella Pertussis ◽  
Tracheal Ring ◽  
Fixation Method ◽  
Bacterial Cells ◽  
Ciliated Cells ◽  
Scanning Electron

Infection of mouse tracheal organ culture with Bordetella pertussis resulted in ciliostasis within 36 h. Scanning electron microscopy revealed that B. pertussis attached exclusively to ciliated cells but did not induce expulsion of this cell type at a test interval of 48 h. Mouse oviduct organ culture infected with B. pertussis demonstrated the same strict tropism for ciliated cells as in the tracheal ring system. Only ciliated cells were parasitized, becoming heavily colonized 48 h postinfection. Infected ciliated oviduct cells were not extruded. A fixation method which enhances fine structure was used in the scanning electron microscope studies. Bacterial fimbriae were not observed as the method of attachment of B. pertussis to cilia but fine fibers were seen extending between cilia and bacterial cells.

Specificity of bacterial attachment sites on the filamentous diatom Navicula confervacea (Bacillariophyceae)

1992 ◽  
Vol 38 (7) ◽  
pp. 676-686 ◽  
Author(s):  
James R. Rosowski
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Adhesion ◽  
Bacterial Flora ◽  
Bacterial Attachment ◽  
Aqueous Environment ◽  
Bacterial Development ◽  
Attachment Sites ◽  
Attachment Structures ◽  
Scanning Electron

The association in soil–water cultures of bacteria with the siliceous wall (frustule) of Navicula confervacea was examined with scanning electron microscopy. This diatom is filamentous through serial valve–face unions. Thus, the valve mantle and girdle bands are exposed to the aqueous environment and its bacterial flora, whereas the internally isolated adhering valve–face surfaces are not. Secretion of diatom mucilage strands occurred largely from parallel slits in the valve mantle and from valve–band and band–band sutures. These strands appeared to create a surface environment that discouraged bacterial adhesion. However, as the diatoms divided, their newly exposed mucilage-free bands provided a substratum for bacterial attachment. Dense aggregates of bacteria sometimes occurred at frustule apices, where filaments most easily bend and where recently formed adjacent hypovalves emerge. Along mucilage-free segments of the diatom filament, bacterial development occasionally engulfed the frustules; more commonly, bacteria were sparse but in specific locations. Bacterial attachment structures were mostly straight fibers, even on cocci, whereas strands from diatoms were contorted. Attachment by rods and spirilla was most often by their apices, with or without obvious lateral anchoring fibers. Scanning electron microscopy of cocci, rods, vibrio, and spirilla suggests that these bacteria initially prefer mucilage-free attachment sites near openings likely to leak cellular nutrients, i.e., slits of the mantle and band sutures rather than on the substratum between them, where presumably, other nutrients would have been available through their adsorption from the medium. Key words: bacterial adhesion, diatom girdle, mucilage, trail fibers.

scholarly journals Low-density polyethylene films incorporated with silver nanoparticles to promote antimicrobial efficiency in food packaging

2019 ◽  
Vol 26 (4) ◽  
pp. 353-366
Author(s):  
Sabrina da Costa Brito ◽  
Joana D Bresolin ◽  
Kátia Sivieri ◽  
Marcos D Ferreira
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silver Nanoparticles ◽  
Food Packaging ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Bacterial Cells ◽  
Scanning Calorimetry ◽  
Polyethylene Films ◽  
Scanning Electron

Technological innovations in packaging are intended to prevent microbiological contaminations for ensuring food safety and preservation. In this context, researchers have investigated the antimicrobial effect of low-density polyethylene films incorporated with the following concentrations of silver nanoparticles: 1.50, 3.75, 7.50, 15.00, 30.00, 60.00, and 75.00 µg/ml. The films were characterized using field emission gun scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, and differential scanning calorimetry. From the results of these techniques, it could be concluded that the silver nanoparticles incorporated in the low-density polyethylene films did not influence their physical, chemical, and thermal properties. The direct contact assays, shake-flask assays, and bacterial images obtained using scanning electron microscopy were used to analyze the antimicrobial activity of the films. In the microbial analyses, it was verified that the nanostructured films exhibited antimicrobial properties against all the microorganisms studied, although more notably for fungi and Gram-negative bacteria than the Gram-positive bacteria. Moreover, it was discovered that the packages, in which silver nanoparticles were incorporated, inhibited the growth and reproduction of bacterial cells during the early stages. These results suggest that the extruded low-density polyethylene films incorporated with silver nanoparticles may be an essential tool for improving food quality and safety.

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