182 



PROVASOLI 



[CHAP. 8 



Table VI 

 Vitamin Content of Algae 



a Dry weight of alga. 



* B12 as assayed with micro-organism: E. g. = Euglena gracilis, E. c. = E. coli. 

 c 65-70% of this is true B12 ; the remainder is pseudo-Bi2 and factor A. 

 d Bacteria-free. 



See also Kanazawa, A., 1962. Studies on the vitamin B -complex in marine algae. I On 

 vitamin content. Mem. Fac. Fish. Kagoshima Univ., 10, 38-69. 



vitamins were synthesized by the seaweeds or absorbed from the environment 

 (it is well known that seaweeds accumulate inorganic ions 100-1000-fold). 

 Ericson (1952) found that Pelvetia caniculata has a very poor ability to con- 

 centrate radioactive B12, but when collected in nature it contains at least 

 0.5 [xg Bi2/g; Polysiphonia fastigiata concentrates radioactive Bi 2 90-fold, but 

 when collected from nature is devoid of B12. Since the quantity of cobalamins 

 in sea-water is very low, these data favored the hypothesis that B12 is syn- 

 thesized by seaweeds. Later, Ericson and Lewis (1953) found that epiphytic 

 bacteria of seaweeds produce B12 and non-Bi2 cobalamins : from this and other 

 considerations they conclude that the Bi 2 -compounds in seaweeds are probably 

 of bacterial origin, even though true B12 is preponderant in seaweeds and non- 

 B12 cobalamins are predominantly excreted by the epiphytic bacteria. The 

 question can only be answered by the use of aseptic cultures of seaweeds; so 

 far the red algae which have been cultured aseptically. Goniotrichum elegans 



