Yeasts in Marine Environments 331 



dilution of inhibitory metabolites, and continous bathing of the 

 developing cells with nutrients. Tlie prolonged time required 

 for positive assimilatory reactions in stationary cultures was there- 

 by reduced to less than five days, and the development of latent 

 reactions was accelerated. 



OBSERVATIONS AND CONCLUSIONS 



Examination of waters and sediments from Florida coastal 

 regions and adjacent off-shore areas demonstrated that yeasts 

 were present with rare exception in all sample areas; however, 

 distinctive qualitative and quantitative differences were observed. 

 Environmental factors were found to be of major importance in 

 detennining die character of the resident yeast population. Pop- 

 ulation densities may be contingent upon the availability and 

 concentration of organic material required for the growth and 

 reproduction of the indigenous yeast flora. Sea water may nor- 

 mally contain tens or hundreds of yeast cells per liter, however, 

 in regions of grass and algal beds there may be 5,000 to 6,000 

 viable yeast cells per liter of water. Determination of the yeast 

 flora of marine vegetation ( e.g., species of Thalassia, Penicillus, 

 Udotea, Sargassiim, Laurencia, etc.) by direct culture and sur- 

 face washing techniques indicated that yeasts are relatively sparse 

 on these plants and appear to be incidental transients. Allen and 

 Dawson ( 1 ) reported that certain algal f onus elaborate anti- 

 bacterial substances and it is reasonable to assume that yeasts may 

 also be influenced by such organic compounds. Our observations 

 suggest that the organic constituents present in algae and grasses 

 normally become accessible to the yeasts only after death and 

 dissolution of the plants. The complex algal polysaccharides are 

 probably reduced to simpler molecules by bacteria and actino- 

 mycetes before they serve as energy sources for most yeasts. 

 Indirect evidence for this was the failure of yeasts {Candida 

 parapsilosis, C. twpicalis, C. olbicans, Cryptococctis albidiis, and 

 RJiodotorula madlaginosa) to grow either in sterile extracts of 

 fresh algae (BatopJiora oerstedi, Udotea flabeUum, Penicillus 

 captitatus, Laurenia poitei) or in extracts supplemented witli all 

 growth requirements except a carbon source. Decomposing 

 giant kelp from California waters was foimd to have viable cell 



