Aphanizomenon flos-aquae Saxitoxin

The saxitoxins have also been found in the freshwater cyanophyte Aphanizomenon flos aquae (9,1 ) and, quite recently, in tropical marine coralline algae of the genus Jania (11)... 

Two other suspected alkaloid producing cyanobacteria strains, Anabaena flos-aquae NRC-525-17 and Aphanizomenon flos-aquae NH-5, are now being studied. The toxin of flos-aquae NRC-525-17 (anatoxin-a(s)) is thought to have CNS stimulating properties (7) and that of Aph. flos-aquae NH-5 (aphantoxin) is thought to produce the paralytic shellfish poisons saxitoxin and neosaxitoxin (Fig. 1)... 

Figure 1. Structure of anatoxin-a from Anabaena flos-aquae NRC-44-1, saxitoxin and neosaxitoxin. Saxitoxin and neosaxitoxin is produced by certain species of marine algae and by the freshwater cyanobacteria Aphanizomenon flos-aquae NH-5.

Saxitoxin may be found in oysters, common whelks and other species of marine molluscs, but can occur also in some microscopic freshwater blue-green algae Aphanizomenon flos-aquae) and red macroscopic algae of the genus Jania, which become the source of saxitoxin in crab meat. 

---