Spherical body formation in the spirochaeteBrachyspira hyodysenteriae

Abstract

When cultures of Brachyspira hyodysenteriae were grown under a wide range of in vitro conditions, at least 1% of the cells formed spherical bodies different to the normal helical form. This percentage increased considerably in aging cultures or following their incubation in caramelized media. Spherical body formation was initiated from a terminal localized swelling of the outer sheath followed by a retraction of the protoplasmic cylinder into the resulting swollen vesicle. As this occurred, the periplasmic flagella seemed to unwind from the protoplasmic cylinder. Once retracted, the protoplasmic cylinder was found to be wrapped in an organized manner around the inner surface of the membrane of the swollen vesicle. Although most were 2-3 microm in diameter, some much larger spherical bodies (6-12 microm diameter) were occasionally seen, with a corresponding increase in the visible number of peripheral protoplasmic cylinder cross-sections. Spherical bodies from older cultures did not contain protoplasmic cylinders arranged around the periphery, but instead were characterized by the presence of a centrally located, electron-dense body c. 0.5-0.8 mum in diameter. Brachyspira hyodysenteriae spherical bodies differ in both their structural organization and probable method of formation from similar structures described in other spirochaete genera.

Brachyspira pilosicoli-induced avian intestinal spirochaetosis

“…Another interesting effect of lactic acid is that it induces the formation of ‘spherical bodies’ formed by the retraction and swelling of both ends of the bacterium, which tends to create a sphere shape. At this stage, the bacterium is still viable but in a dormant state ( 78 ).…”

In vitro antagonistic activities of Lactobacillus spp. against Brachyspira hyodysenteriae and Brachyspira pilosicoli

“…The cells were then washed in 100 % ethanol for 10 min before being dried in a critical-point dryer (Balzers CPD 020) and coated with gold. For Transmission electron microscopic (TEM -JEOL 1011/micrograph MegaviewIII SIS) observations, the protocol was adapted from Wood et al, (2006). Cells were washed through a cacodylate series (400, 300 and 200 mM), before being dehydrated through an ethanol gradually increased concentration series and infiltrated with resin.…”

Non-destructive observation of intact bacteria and viruses in water by the highly sensitive frequency transmission electric-field method based on SEM

“…In particular, scanning electron microscopy (SEM) has widely been used to analyse bacterial and viral structures [7][8][9][10][11][12]. However, SEM observations of these specimens under high vacuum conditions require specific sample preparation protocols involving glutaraldehyde fixation, negative staining, cryo-techniques and metal coating or labelling to avoid electrical radiation damage [10][11][12][13].…”