POLYSACCHARIDE-SPLITTING ENZYMES 303 



and Avery finally discovered the spore-bearing bacillus which they 

 designated as the "SIII bacillus." 



When grown in the synthetic medium, the organism appears as a 

 minute Gram-negative bacillus, at times smaller than the Pfeiffer 

 bacillus. It contains metachromatic granules ; it grows diffusely in 

 peptone solution and in this medium sedimentation of the growth 

 occurs after several days' incubation. When cultivated in peptone 

 solution or in plain broth the organism appears as a fairly large, 

 actively motile bacillus, having peritrichous flagellae, the young 

 cells measuring 2 to 3|J by 0.5p. Short chains and diploforms are 

 often observed. In broth the bacilli are at first Gram-positive and 

 do not autolyze readily, but in the mineral medium the bacilli rap- 

 idly become Gram-negative and undergo almost immediate self- 

 digestion. The spores resist heating for thirty minutes at 75° but 

 are killed by boiling for five minutes. On plain nutrient agar free 

 of dextrose, growth occurs in the form of small, whitish colonies, 

 two millimeters in diameter, circular, slightly raised, umbilicated, 

 with entire edge and fairly smooth surface. 



In the media tested, the organism is strictly aerobic and exerts 

 its saccharolytic action on Type III Pneumococcus within the 

 range pH 6.2 to 7.8 at room temperature and at 37.5°. The iso- 

 lated enzyme, however, is equally active under both anaerobic and 

 aerobic conditions, and it is likely that this soluble principle be- 

 longs to the group of hydrolytic enzymes. 



Dubos and Avery then found that the enzymatic action of the 

 culture could be enhanced by frequent transplantation, and that 

 the enzyme was present in filtered autolysates of the cultures. The 

 action of the enzyme was limited, of all the substances tested, to 

 the Type III polysaccharide, since it failed to decompose the car- 

 bohydrates of Types I, II, and VIII* Pneumococcus, and those of 

 Types A, B, and C of Friedlander's bacillus, of Hemophilus influ- 

 enzae Type a, and of gum arabic which, it may be recalled, gives a 



* Personal communication from Dubos. 



