144 



Marine Microbiology 



Fig. 4. Response of a marine thiamine-deficient bacterium (B1866) to 

 various marine algae applied on seeded plates containing medium B with- 

 out vitamin Bi. A, Sargassiirn lendigennn; B, Gonyaiilax tamarensis; C, 

 Zonaria zonalis; D, Wrangelia argiis; E, Acanthophora spicifera; F, Lauren- 

 cia obtiisa; G, Penicillus capitatus; H, Ceramium nitens; I, Halimeda 

 opiinfia; J, Caiderpa racemosa; K, Coelothrix irregularis. Note the dark 

 zones of inhibition around applications B, C, and D, and the light areas 

 of growth stimulation by thiamine supplied by the algae. 



disappear from solution in the waters of Long Island Sound 

 concurrently with the development of extensive blooms of the 

 cobalamin auxotroph, Skeletonema costatinn, one may inquire 

 what is the fate of these substances? Similar blooms of dino- 

 flagellates often occur in tropical waters. The organisms that are 

 dominant in these blooms belong to groups which have pro- 

 nounced auxotrophic tendencies, but their absorption and use of 

 vitamins is not well understood. 



Microbiological assays of lyophihzed powders of Skeleto- 

 nema and Gomjaidax (?) blooms were performed with various 

 auxotrophic marine isolates, and with two strains of E. coli, 113- 

 13 sensitive to cobalamins, and 26-18 sensitive to methionine. 

 Both blooms showed appreciable vitamin B12 activity and other 

 vitamins, along with antibiotic properties, exhil^ited on suitable 

 assay agar plates seeded with indicating bacteria. Apparently 

 blooms can absorb certain vitamins, as well as synthesize others 

 and store them as a vast reservoir, available for predators and 

 direct utilization by those auxotrophic microbes that can tolerate 

 the antibiotic properties. 



