82 



Marine Microbiology 



A Nitrosomonas europoea (from Engle and Alexonder ,1958 ) 

 # Marine bacteria growing in 310 mM (N H^ Ip SO^ 

 X Marine bacteria growing in 2.5 mM (NH4)2 SO4 



to 

 kj 



k 



kj 



100 



9.5 



Fig. 5. The effect of hydrogen ion concentration on the respiration of 



Nitrosoinonas europaea. 



europaea responded similarly, having maximum oxygen uptake in 

 a 50 mM solution between pH 7.25 and 7.9 and in a 250 niM 

 solution between pH 7.3 and 7.75 (Fig. 5). When the ammonia 

 concentration was increased to 750 mM, optimum respiration 

 occurred only between pH 7.4 and 7.6. 



DISCUSSION 



These studies have yielded the first clues to the site of 

 nitrification in the oceans. In waters less than 100 m deep, 

 nitrification must occur within both the water column and sedi- 



