Activity of salicylic acid on the growth and biochemism of Chlorella vulgaris Beijerinck

This study was conducted to investigate the influence of salicylic acid (SA) on the growth and changes of nucleic acids, protein, photosynthetic pigments, sugar content and photosynthesis levels in the green alga Chlorella vulgaris Beijerinck (Chlorophyceae). The most significant changes in the content of nucleic acids and proteins was observed at the concentration 10(-4) MSA between 8 and 12 day of cultivation. This concentration of SA increased the number of cells (about 40%) and content of proteins (about 60%) and its secretion to the medium. The slight stimulation of protein secretion occurred on the 12th day of cultivation at concentration 10(-4) M, while in the range of 10(-5) M to 10(-6) M the protein secretion was inhibited. SA also stimulated the content of nucleic acids, especially RNA by 20-60%, compared with the control. The most stimulating influence upon the contents of chlorophylls a and b (50-70%), total carotenoids (25-57%), sugar (27-41%) and intensity of net photosynthesis (18-33%) was found at 10(-4) M of SA. At the concentration of 10(-6) MSA the slight inhibition of growth and biochemical activity of the algae was recorded at the first days of cultivation.