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Imaging the surface of Staphylococcus aureus by atomic force microscopy.

The surfaces of four strains of Staphylococcus aureus, which differed in their expression of capsular polysaccharides, were examined using atomic force microscopy. The images show that it is possible to get information about surface characteristics of S. aureus using atomic force microscopy (AFM) following simple preparation. Strains Smith Diffuse (serotype 2), Reynolds (serotype 5), Wood-46 (capsule negative) and JL243 (capsule negative) were grown on medium known to promote the expression of capsular polysaccharides. The bacteria were air-dried prior to being imaged using tapping-mode AFM. Differences in the appearance of the bacterial surfaces were evident between the strains. The two capsule-negative strains exhibited a smooth regular surface, as opposed to the mucoid appearance of the two strains having polysaccharide capsules. Moreover, comparison of images of the heavily encapsulated serotype 2 strain and the serotype 5 strain indicates that a type 2 capsule can be distinguished from a type 5 microcapsule.

Microscopy, Atomic Force↗

PubMedDate not supplied

[The correlation between milk flow, vacuum fluctuations and decrease in vacuum in the long milk tube at the claw in different milking machines. An introductory examination (author's transl)].

Four different milking machines have been examined for vacuum fluctuations and vacuum decrease in the long milk tube at the claw. Measurements were performed in 3 cows milked with Alfa-Laval high line HP 100, 11 cows in 3 herds milked with Alfa-Laval high line Duovac 300, 5 cows milked with Erland low line milking equipment, and in 3 cows milked with Strangko high line milking equipment. The recordings were done in the cowhouse during the daily dairy management. The milk flow for each cow was measured 24 hrs after the vacuum recordings using Milko-Scope. Compared to the other 3 milking machines, Duovac 300 had a significant higher increase in vacuum fluctuations and vacuum decrease with the increase in milk flow. Just small differences existed between Alfa-Laval HP 100 and Strangko milk pipe line equipments. Smaller vacuum fluctuations and vacuum decrease were recorded in the low line milking equipments compared to the other types. The difference was significant (P = less than 0.001). Significant correlations between milk flow and decrease in vacuum, and between milk flow and vacuum fluctuations were not found for the low line milking machine examined.

Animals↗