634 



Marine Microbiology 



partial replacement of NaCl by KCl and MgCl- demonstrated the 

 non-specific nature of an appreciable component of the salt re- 

 quirement for this organism. 



OSMOLAL CONC 



Fig. 3. 3a. Partial replacement of the growth for NaCl by KCl using Vibrio 

 MB 22. NaCl (0.125 osmolal) was added to the basal medium. KCl (open 

 circles). NaCl (closed circles). Incubation five hours. 3b. Partial replace- 

 ment of the growth requirement for NaCl by MgCL using Vibrio MB 22. 

 NaCl (0.1 osmolal) was added to the basal medium. MgCL (open circles). 



NaCl (closed circles). 



Partial Replacement of NaCl with Sucrose 



Vibrio MB 22 fennented sucrose with the production of acid, 

 which inhibited growth in the unbuffered medium; consequently, 

 quantitative comparisons of growth rates were impossible. 

 Periodic neutralization of the cultures with NHiOH during in- 

 cubation allowed good growth; neutralization was essential only 

 during the early period of incubation, suggesting the accumula- 

 tion of a buffering organic acid. Fumaric, succinic, citric and 

 glutamic acids peniiitted growth in media containing 0.4 M NaCl 

 and inliibitory amounts of sucrose (0.1%). The organic acids 

 were neutralized with NH4OH. Succinic acid was the most ef- 

 fective and its fimction as a buffer was apparently supplemented 

 by its being metabolized, thus increasing the available base. The 



