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 growth, photosynthesis, and dark respiration in the green alga Chlorella kessleri. C-14-protein hydrolysate indicated a maximum incorporation level by 5 mu M atrazine after 48 hr. Progressive reduction in protein synthesis was associated with increasing herbicide concentration at all experimental periods. The herbicide had preferential effect on the associated fatty acid composition of total and phospholipids. After 24 and 48 hr the herbicide stimulated fatty acids synthesis at concentrations where photosynthesis was inhibited. Meanwhile, stearic and miristic acids disappeared at 15 mu M after 24 hr and the total polyunsaturated 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 the total saturated fatty acids were completely inhibited. (C) 1994 Academic Press, Inc.