Effects of detergents on algal growth and physiological activities

The effects of synthetic detergents and soap on algal growth and physiological activities were studied using a freshwater alga, C. pyrenoidosa and a marine alga, T. pseudonana. The tested synthetic detergents inhibited completely the growth of both algae at concentrations above 10 mg/l (as surface-active agent). The tested soap inhibited the growth of T. pseudonana at a concentration of 100 mg/l. The growth of C. pyrenoidosa was not influenced by the soap. The synthetic detergents decreased the photosynthetic activity, ATP content and chlorophyll a content of both algae, especially those of T. pseudonana at concentrations above 10 mg/l. The soap increased the activity and contents of C. pyrenoidosa, but it gave inhibitory effects on those of T. pseudonana at a concentration of 100 mg/l. The mechanism of this inhibition seemed to be different from that of inhibition by the synthetic detergents. The characteristic differences between the algae were consequently suggested. The phosphate-containing and phosphate-free synthetic detergents showed the same inhibitory effects as LAS.