EFFECT OF TRICHLORFON ON N-2-FIXING CYANOBACTERIUM ANABAENA PCC-7119

The growth of Anabaena PCC 7119 is affected by the organophosphorus insecticide trichlorfon, the inhibitory effect being dependent on the concentration of insecticide on the culture medium. The inhibition can be related to the unbalanced cell composition of trichlorfon-grown cells that have a decreased amount of phycobiliproteins, chlorophylls, and total proteins and an increased concentration of carbohydrates. An explanation for the lowered content in nitrogen compounds may lie in the inhibitory effect of the insecticide on N2 fixation. Cell cycle is also affected since cell volume increases, irregular divisions occur, and the number of cells per filament is shortened. However heterocysts frequency is not altered. The sensibility of Anabaena PCC 7119 indicates that trichlorfon may affect negatively natural populations of cyanobacteria. © 1990 Springer-Verlag New York Inc.