BIOCHEMISTRY OF BACTERIAL LUMINESCENCE 



I 



20 40 



DURATION OF IRRADIATION (MIN) 



60 



Fig. 



9. Effect of ultraviolet illumination on luminescence of bacterial extracts. 

 Two per cent centrifuged extract diluted (1:1) with 0.01 M phosphate, pH 

 7.0, and illuminated with stirring (12 in. distant) by a Keese ultraviolet 

 spot lamp (365 m/x). Samples withdrawn at times indicated (0.4 ml) and 

 tested widi 300 iig of DPNHo. Boiled bacterial extract did not restore ability 

 to luminesce to irradiated extracts. 



violet may be due to the photo-induced formation of aldehyde. The 

 completely ultraviolet-inactivated system cannot be reactivated in our 

 hands either by addition of the known necessary components or by 

 the addition of boiled active extracts, suggesting that the protein is 

 destroyed under these conditions. 



Comparative Biochemistry 



Although little is known concerning the evolution of biolumines- 

 cence in luminous bacteria or other luminous forms, it may be pos- 

 sible to draw some tentative conclusions from the comparative bio- 



