578 Marine .Microbiology 



Staphylococcus aureus, and Serratia marinorubra) was generally 

 less in filter-sterilized natural sea-water samples, supplemented 

 witli essential minerals, glucose, and complex organic additions 

 such as yeast extract and casein hydrolyzate, than in similar media 

 prepared with artificial sea water. The inhibitory effect of pelagic 

 sea-water samples varied with depth and location: samples ob- 

 tained adjacent to the sea bottom were more inhibitory than any 

 of the pelagic samples tested. These findings indicate that natural 

 sea water contains factors inhibitory to bacteria. 



On the other hand, growth curves of the test bacteria 

 showed a lag period in natural sea-water samples slightly shorter 

 than that in enriched synthetic sea-water media. 



ACKNOWLEDGMENT 



The author thanks Miss Susan Wright for technical assistance. 

 This work was supported by grant E-1768(C2) from the National 

 Institute of Allergy and Infectious Diseases of the National In- 

 stitutes of Health, Bethesda 14, Maryland. 



REFERENCES 



1. Belser, W. L.: Bioassay of organic micronutrients in the sea. Proc. 



Nat. Acad. Set., 45:1533-1542, 1959. 



2. Carlucci, a. F. and Pramer, D.: Factors affecting the survival of 



bacteria in sea water. Appl. Microbiol., 7:388-392, 1959. 



3. Greenberg, a. E.: Survival of enteric organisms in sea water. Public 



Health Repts. (U.S.), 71:77-86, 1956. 



4. Janxasch, H. W. and Jones, G. E.: Bacterial populations in sea water 



as determined by different methods of enumeration. Limnol. Ocean- 

 ogr., 4:128-139, 1959. 



5. Johnston, R.: Biologically active compounds in the sea. J. Mar. Biol. 



Assoc. U. K., 34:185-195, 1955. 



6. Jones, G. E.: Biologically active organic substances in sea water. Pre- 



prints Intern. Oceanogr. Congr., 921-922, 1959. 



7. Kriss, a. E., Abyzov, S. S., Lebedeva, M. N., Mishustina, I. E. and 



MiTSKEViCH, I. N.: Geographic regularities in microbe population 

 (heterotroph) distribution in the world ocean. /. Bacterid., 80:731- 

 736, 1960. 



8. Lucas, C. E.: External metabolites in the sea. Mar. Biol. Oceanogr. 



Siippl. to Deep-Sea Res., 3:139-148, 1955. 



9. Lyman, J. and Fleming, R. H.: Composition of sea water. /. Mar. Res., 



3:134-146, 1940. 



