EFFECT OF ATRAZINE HERBICIDE ON GROWTH, PHOTOSYNTHESIS, PROTEIN-SYNTHESIS, AND FATTY-ACID COMPOSITION IN THE UNICELLULAR GREEN-ALGA CHLORELLA-KESSLERI

Sublethal atrazine concentrations induced a general inhibition on grow th, photosynthesis, and dark respiration in the green alga Chlorella k essleri. C-14-protein hydrolysate indicated a maximum incorporation le vel by 5 mu M atrazine after 48 hr. Progressive reduction in protein s ynthesis was associated with increasing herbicide concentration at all experimental periods. The herbicide had preferential effect on the as sociated fatty acid composition of total and phospholipids. After 24 a nd 48 hr the herbicide stimulated fatty acids synthesis at concentrati ons where photosynthesis was inhibited. Meanwhile, stearic and miristi c acids disappeared at 15 mu M after 24 hr and the total polyunsaturat ed fatty acids were not affected after 48 hr. Fatty acid synthesis was sensitive to treatment at 72 hr by 5 and 10 mu M atrazine, whereas th e total saturated fatty acids were completely inhibited. (C) 1994 Acad emic Press, Inc.