Yeasts in Marine Eyxz'ironments 339 



SUMMARY 



1. At least 30 different species of yeasts have been isolated 

 from the marine environments studied. The distribution of species 

 as well as their numbers and metabolic characteristics are gov- 

 erned by existing environmental conditions. 



2. In regions of high organic matter, such as grass and algal 

 beds, high concentrations of plankton, and current boundaries, a 

 quantitative increase in the yeast population has been observed. 



3. Due to low organic content in the open ocean, the resi- 

 dent yeasts rely mainly on oxidative metabolic processes. 



4. The exterior surfaces of living marine algae do not ap- 

 pear to sustain significant yeast populations, apparently the native 

 algal polysaccharides become available only after prior degrada- 

 tion by other micro-organisms. 



5. Within the intestinal tract of certain marine fish, partic- 

 ular yeast species (e.g., Metsclinikowiella zoheUii) exist in 

 greater concentration than in the surrounding water, whereas 

 other yeast species occur as incidental transients. 



6. Yeasts occur in marine sediments but appear to be limited 

 to the upper surface layers. 



7. With rare exception, the yeasts encountered in this study 

 represent terrestrial species of transitory status in the marine 

 situation or adaptive forms which survive in both environments. 

 The Metschnikowiella species are well adapted to life in the 

 sea and more closely conform to the concept of a true marine 

 yeast than any other form encountered. 



REFERENCES 



1. Allen, M. B. and Dawsox, E. Y. : Production of antibacterial sub- 



stances by benthic tropical marine algae. /. Bad., 79:459-460, 1960. 



2. Ahearn, D. G., Roth, F. J., Fell, J. W. and Meyers, S. P.: Use of 



shaken cultures in the assimilation test for yeast identification. /. 

 Bad., 79:369-371, 1960. 



3. Bhat, J. V. and Kachwalla, N.: Marine yeasts off the Indian Coast. 



Proc. Indian Acad. Sci., (B) 4J:9-15, 1955. 



4. Di Menna, M. E.: Non-pathogenic yeasts of the human skin and ali- 



mentary tract: a comparative survey. /. Path. Bact., 68:89, 1954. 



5. Fell, J. W., Ahearn, D. G., Meyers, S. P. and Roth, F. J.: Isolation 



of yeasts from Biscayne Ba\', Fla. and adjacent benthic areas. Lim- 

 nology and Oceanography, 5:366-371, 1960. 



