Autolytic Mechanism for Spheroplast Formation in Bacillus cereus and Escherichia coli

Abstract

mechanism for spheroplast formation in Bacillus cereus and Escherichia coli. J. Bacteriol. 90:1355-1364. 1965.-Spheroplasts of Bacillus cereus strain T and Escherichia coli B were prepared by incubating early log-phase cells in appropriate buffers and stabilizers for 3 hr at 30 and 37 C, respectively. Upon incubation in 0.05 M tris(hydroxymethyl)aminomethane buffer osmotically stabilized with 16% polyethylene glycol at pH 7.5, 99% of the B. cereus cells formed spheroplasts; 90% of the E. coli cells were converted to spheroplasts in 0.4 M sodium acetate buffer osmotically stabilized with 1.6 M sucrose at pH 6.0. The extent of spheroplast formation was determined by phase-contrast microscopic examination, by measuring the rate of fall of optical density in the reaction mixture when subjected to osmotic shock, and by viable intact cell counts. The effect of a selected group of metabolic inhibitors on the autolytic system of B. cereus and E. coli has been examined. B. cereus and E. coli wall components comprising 26% of the dry weight of the original cellular material were recovered from dialyzed fractions by precipitation in 70% ethyl alcohol. Chemical and chromatographic analysis of cell-wall hydrolysates from B. cereus and E. coli indicated the presence of glucosamine, alanine, lysine, glycine, aspartic acid, diaminopimelic acid, glutamic acid, and muramic acid.

Morphological Changes during Conversion of Clostridium saccharoperbutylacetonicum to Protoplasts by Sucrose‐Induced Autolysis

“…In sucroseinduced autolysis, the clostridial cells were converted into protoplasts through the morphological changes beginning both at the middle and one pole. The other morphological changes corresponded well with each case of lysis of E. coli (3,8,13). We will report the role of autolysin and sucrose in the morphological changes of the clostridial cells which occur during sucrose-induced autolysis in our next paper.…”

“…Cells of E. coli treated penicillin were converted into the spheroplasts through the morphological change beginning only at the middle (8). On the other hand, the cells autolysed in buffer were converted into the spheroplasts through the morphological change beginning only at one pole (13). In sucroseinduced autolysis, the clostridial cells were converted into protoplasts through the morphological changes beginning both at the middle and one pole.…”

“…Many kinds of bacteria have been lysed and converted into protoplasts or spheroplasts by using wall-lytic enzymes (1,12) or antibiotics (2,17). Sometimes , S. OGATA ET AI protoplasts were produced autolytically for the advantage of having protoplasts in the natural state by eliminating contamination by extra cellular supplements (7,9,11,13). In these investigations, sucrose was used to prevent the developing protoplasts from further lysis.…”

INFLUENCE OF OSMOTIC PRESSURE ON TRANSFORMABLE AND NON TRANSFORMABLE VARIANTS OF NEISSERIA MENINGITIDIS

“…It has previously been suggested that increased osmotic pressure activates auto-lysis in Staphylococcus aureus (9). I t is also of interest that most active autolysis in intact bacteria has usually been observed after washing of the cells in distilled water (4, 9,10). As found in other systems (9, l o ) , maximal autolytic activity in N .…”

Site of Cellular Autolysis in Micrococcus lysodeikticus (luteus) as Seen by Electron Microscopy

“…The cellular autolysis of bacteria is a phenomenon attributable to the hydrolytic degradation of cell wall peptidoglycans by their own enzyme(s). Studies by light and electron microscopy on Bacillus cereus and Escherichia coli (9), Clostridium botulinum (6), Clostridium perfringens (5), Streptococcus faecalis (3,4), group H streptococci strains Wicky and Challis (13), and Lactobacillus acidophilus (2) have revealed that cytoplasmic materials leak outward at the septal region by the autolysis, and that the autolysis was initiated at the septal site of dividing cells and at one pole of just separated cells, where cell wall materials were synthesized actively. In particular, Higgins et al (3) demonstrated by electron microscopy of thin sections that the initiation of cellular autolysis in dividing cells of S. faecalis was brought about by the dissolution of cell wall at the leading edge of nascent cross wall.…”