266 



C. WEIBULL AND K. G. THORSSON 



■ :- •■^i-;-- 



*^^<_1>>1 



^Q' 



>♦ ^ ♦-»^ 



Fig. 6. The polymorphism of phage particles of Bac. iiiyco- 

 ides at the place of lysis of bacterial cell. The heads of phage 

 particles with ring and spiral form (enclosed in squares), 

 with solid granules (enclosed in rings) and formless (shown 

 by pointers). 



or spirals. The filament twisted more tightly forms 

 the head of a phage particle with granules, which 

 optically reflects the places of bending of the fila- 

 ment that forms the head. The filament twisted very 

 tightly gives an impression of a homogeneous head 

 of a phage particle (fig. 6). 



More and more data are accumulated testifying 

 to the fact that a phage particle is a spiral or clew 

 twisted filamentous aggregate of protein macro- 

 molecules with a free end in the shape of a tail. 



References 



1. Chapman, G., Hillier, J., and Johnson, F., J. 



Bacterial . 61, 261 (1951). 



2. Freeman, V., J. Bacteriol. 61, 675 (1951). 



3. Hercik, F., Casopis Lekdrii Ceskych 89, 91 (1950). 



4. — ibid. 90, 925 (1951). 



5. Jesaitis, M. and Goebel, W., /. Exptl. Med. 102, 733 



(1955). 



6. Kriss, a. E. and Tikhonenko, A. S., DAN 96, 42\ (1952). 



7. — DAN 93, 353 (1953). 



8. NoDA, H. and Wyckoff, R., Biochiin. Biophys. Acta 8, 



381 (1952). 



9. Pockotinsky, I. S., Krivisky, A. S., and Luzyanina, 



T. J., Zhunial mikrobiologii, epidemiologii i immutio- 

 biologii 5, 19 (1951). 

 10. Williams, R. and Fraser, D., J. Bacteriol. 66, 45S {1953). 



Comparative Studies on Sections of Intact Cells, Protoplasts and 



"Ghosts" of a Bacillus species 



C. Weibull and K. G. Thorsson 



Central Bacteriological Laboratory of Stockholm City, Stockholm 



In 1952 it was shown (8, 12) that the eff"ect of 

 the enzyme lysozyme on gram-positive bacteria 

 is due to a dissolution of the bacterial cell wall. 

 Soon afterwards it was demonstrated (13) that if 

 the lysozyme treatment is carried out in a medium 

 containing a protective agent such as sucrose or 

 polyethylene glycol, the cell wall can be digested 

 away without ensuing lysis of the protoplasm. Free 

 bacterial protoplasts are thus formed. This indicates 

 that the far-reaching lysis ordinarily effected by the 

 enzyme, resulting in the formation of membraneous 

 structures or "ghosts", is due to secondary phe- 

 nomena, probably to a great extent of osmotic nature. 



The protoplasts were prepared as usual by lysozyme 

 treatment of the cells in a sucrose containing medium. 

 "Ghosts" were obtained by suspending protoplasts in 



dilute phosphate buffer. Fixation was effected by treating 

 the structures with 1 per cent osmic tetroxide at 37°C 

 for two hours. The fixed specimens were then dehydrated 

 in alcohol, embedded in a mixture of 1 part of methyl 

 and 9 parts of butyl methacrylate and sectioned. 



The organism investigated was a Bacillus strain 

 named Bacillus M by Tomcsik (12). It is closely 

 related to Bacillus mcgaterium and has even been 

 regarded as a variant of this species (11). 



Electron micrographs of sections of Bacillus M 

 cells reveal the same organisation as found in all 

 other bacteria investigated so far with the same 

 technique (fig. 1). 



The protoplasts show essentially the same struc- 

 tural organisation as the intact cells, except for the 

 absence of the cell wall in the former bodies (fig. 2). 



