Antimicrobial activity of plankton

The antimicrobial activity of planktonic organisms was examined. Seven species of phytoplankton and 4 species of zooplankton were used. They were obtained by mass culture or collected from the field. Ether and aqueous extracts were prepared and their activity was measured against 8 species of microbe by the paper disc method. The ether extract of Asterionella japonica showed distinct and widespread activity to Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa , and Mycobacterium smegmatis . The extracts of Platymonas tetrathele and Scenedesmus acutus exhibited weak activity to S. aureus . In the aqueous extracts of the tested species of phytoplankton, antimicrobial activity was not recognized. None of the tested samples of zooplankton showed the activity except for the ether extract of Artemia salina , which weakly inhibited the growth of E. coli .