LYSOZYME AND BACTERIOPHAGE 



12] 



produced in different, culture media, which are, perhaps, a commonplace to many- 

 bacteriologists, tend to obscure important generalisations and reveal the need for 

 systematic scientific investigation of culture media by all available methods. 



It might be anticipated that exclusion of air would always accelerate the estab- 

 lishment of reductive conditions in cultures. Actually, however, it is found with 

 some aerobic bacteria studied that the potential falls more sluggishly when air is 

 excluded. The rapid development of intense reducing conditions requires the 

 presence of oxygen for the reducing activities of the cells to reach their maximum 

 intensity. Even when cultures are agitated and aerated vigorously, quite intense 

 reducing conditions may be established, especially in the case of those organisms 

 which do not form peroxide in cultures. These facts may be regarded in two ways. 

 They indicate the comparatively slight effect of molecular oxygen on the potentials 

 of cultures, and they indicate the avidity which aerobic bacteria evince for the 

 oxygen they require for metabolic processes. 



-»-0-4 



D 24 48 72 96 120 1 



Time (hours) 



Fig. 31 



Broth cultures of M. lysodeikticus 



c 



> 



Cd 



Time (hours) 



Fig. 32 



Aerated cultures of M. lysodeikticus . Lysozyme 



(human tears) was added at the points marked 



by arrows 



In the case of the aerobe, M. hjsodeiJxticus, it was found that more abundant 

 growth and a more rapid fall in potential were observed when the oxygen supply 

 was increased b}' aeration. {See fig. 31.) 



EFFECT OF LYSOZYME AND BACTERIOPHAGE 



A few experiments have been conducted on the effects of various lytic agents 

 on the electrode potentials of bacterial cultures (Hewitt, 1931). 



When Fleming's lysozyme (present in tears, egg-white, etc.) was added to 

 aerated cultures of Micrococcus hjsodeiJxticus {see fig. 32) there was an immediate fall 

 in potential ; after this period reducing conditions are no longer maintained and 

 the culture is completely lysed. The catalase activity of the organisms is enhanced 

 when they are lysed, although the dehydrogenating activities are destroyed (Penrose 

 and Quastel, 1930). It is probable that during the actual lysing process there is 

 increased enzymic activity followed by destruction of some enzymes when lysis is 

 complete. It is, of course, possible that lysis liberates intensely reducing substances 

 from the interior of the bacteria and the author's disinclination to accept this hypo- 

 thesis is, perhaps, personal rather than logical. 



