80 



Marine Microbiology 



Dense cultures of both Nitrosomonas europaea and its ma- 

 rine analog are yellowish-green, but when they are concentrated 

 by centrifugation, reddish-brown pellets are obtained. Examina- 

 tion of intact cells of both forms in the Carey recording spectro- 

 photometer shows absorption maxima in the 520 and 550 m,"- 



300 



400 500 600 700 



WAVE LENGTH IN MILLIMICRONS 



800 



Vig. 3. Light absorption by ammonia-oxidizing bacteria 



