Electron microscopic observations of Pseudomonas aeruginosa

Abstract

Preparative techniques were developed for t,he purpose of visualizing, by negative contrast, some of the cytological characteristics of unsectioned cells of Pseudontonas ueruginosa.Concent,rated fimbriae free from cells had a length of approximately 1.5 pm and a diameter of 6 nm. Pyocin-like stroct'ures ranging in lengt,li from 32-64 11111 with a width of S.6 nm were "attached" to the terminal ends of a sniall percentage of t,hese finibriae. Microtubules and ringlets having a diameter of 10-20 nm were also visualized in the bacteria. Budding or evagination of cell wall material in multiple units up to 135 nm in length was frequently obscrved in older cultures grown on agar media.Pseudomonas aeruginosu is a graiii negative, motile, polar flagellated bacterium of increasing medical importance. Previous cytological studies have indicated that this organisin contains microtubule-like structures termed rhapidosorries ( YAMAMOTO 1907, BAECIILER et al. 1972) and a number of different types of nieinbranous inclusions, some of which are suggestive of iiiesosoiiies (CARRICK and BERK 1971). I n addition, several reports of one or more types of finihriae have been described for this bacteria (FUERST and HAYWARD , WEISS 1971, BRADLEY 1972.Preparative technicpes developed for the purpose of visualizing internal structures such as rhapidosonies inside unsectioned cells by negative contrast (BAECHLER and BERK 1972) have fortuitously exposed other cytological features such as discrete ringlets or spherical units, evaginations, and specific extrusions associated with autolysis. Consequently, the purpose of this manuscript is t o present sonic cytological features of P. aeruginosa which have not been previously described. Material and methodsOiganism: The strain of Pseudomonas aeruginosa employed for this study was originally a hospit,al isolate maintained in the culture collect.ion of the Department of Microbiology, Wayne State university, School of Medicine. This strain was auto-plaque positive and was designated C,AP+ by BERK (1966).Cnlture medium: Agar slants and plates contained 1.50,.6 (w/v) Bacto agar (DIFCO). The broth media consisted of 2% tryptone, 1% glucose, and 0.504 sodium chloride. The cultures were incubated a t 26 "C or 37 "C for various time periods. Prior to electron microscopy studies, agar slant cultures, incubated more than 72 h., were lightly washed with 0.02 M tris (hydroxymethyl) aminomethane (Tris-HC!) buffer, p H 7.8, containing 0.02 M MgCI, t'o selectively remove the older, autolyzed surface cells.Electron microscopy: Agar blocks (1.5%) of 1.5 cm2x0.5 cm were placed on the end of glass slides. A droplet of the specimen was placed on the surface of the agar and the majority of t'he water and salts was absorbed into i t leaving the specimen in a thin film of moisture 19*

Purification of High Molecular-Weight Antibacterial Proteins of Insect Pathogenic <em>Brevibacillus Laterosporus</em> Isolates

“…Polysheath structures are very stable and can withstand treatments with various chemical and physical factors [51,52]. Electron micrographs of the polysheaths-like structures in the current study were in agreement with previous work in various bacteria [13,34,[52][53][54][55]. A protein of ~30 kD molecular mass was also purified from the crude lysate of Bl 1951.…”

Purification of High-Molecular-Weight Antibacterial Proteins of Insect Pathogenic Brevibacillus laterosporus Isolates

“…Polysheath structures are very stable and can withstand treatments with various chemical and physical factors [51,52]. Electron micrographs of the polysheath-like structures in the current study were in agreement with previous work in various bacteria [13,34,[52][53][54][55]. A protein of ~30 kD molecular mass was also purified from the crude lysate of Bl 1951.…”

The Order Cytophagales (with Addenda on the Genera Herpetosiphon, Saprospira, and Flexithrix)

“…These particles were later identified as tails of a defective phage (Reichenbach, 1967). Since then, the term rhapidosome has unfortunately been used also for rod-shaped particles of a totally different morphology and nature, and has caused unnecessary confusion (Baechler and Berk, 1972;Pate, Johnson, and Ordal, 1967;Yamamoto, 1967).…”