186 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



against fungi, especially in the young mycelial stage, but not against 

 yeasts ; the growth of A . niger was reduced by 60 to 70 per cent and 

 that of A. oryzae by 25 to 30 per cent. The substance was not found in 

 the ash of the organism and was not secreted in the filtrate, but re- 

 mained in the yeast cells. An alkaline reaction was unfavorable to its 

 formation and action. The active substance was soluble in acetone, alco- 

 hol, ether, and chloroform, and was adsorbed by kaolin, Seitz filter, 

 paper, and by the fungus mycelium. It could be removed from the 

 kaolin by treatment with ether or acetone. Acetone-treated yeast no 

 longer had an antagonistic effect, but only a stimulating one. 



According to Schiller (798), yeasts produce a bacteriolytic substance 

 only in a state of "forced antagonism," that is, in the presence of staphy- 

 lococci and certain other bacteria. The substance is thermolabile, since 

 it is destroyed at 60° C. It is active also outside the cell. More recently 

 (144), the active substance of yeast was concentrated. In a crude state, 

 the active material was found to be nonvolatile and readily soluble in 

 water, in 95 per cent alcohol, and in acetone containing a trace of water. 

 It was stable at 100° C. at /)H 7.3. It contained nitrogen but no sulfur. 

 Although a positive biuret reaction was obtained, it appeared that the 

 protein was present as an impurity. 



MICROBIAL LYSOZYME 



The enzyme lysozyme or an antibiotic substance similar to it has 

 often been reported to be produced by microorganisms. Fleming (264) 

 found that the lysozyme of &gg white was soluble in water and in dilute 

 NaCl solution. It was precipitated by chloroform, acetone, ether, alco- 

 hol, and toluene. It was not acted upon by pepsin or trypsin. It was par- 

 ticularly active against micrococci, bringing about their lysis. 



Lysozyme has been found in nearly all mammalian tissues and secre- 

 tions, in certain vegetables, and in bacteria (880). It was found to be a 

 polypeptide containing 1 6 per cent nitrogen and 2 to 3 per cent sulfur 

 and having a molecular weight of 1 8,000 to 25,000. It is soluble and 

 stable in acid solution, insoluble and inactivated in alkaline solutions, 

 and inactivated by oxidizing agents (601). It diffuses in agar and 

 through cellophane, and thus is markedly different from bacteriophage 



