[Studies to investigate the ecological importance of the mass development of Hydrodicyton reticulatum in infiltration basins for drinking water. II. Localization of the active components with the aid of thin-layer chromatography and bioassay detection (author's transl)].

Thin-layer chromatogramms made from ethanol extracts of the green fresh-water alga H. reticulatum were tested by bioassay detection against several strains of Bac. subtilis. The chromatogramms were overlayed with agar, seeded with the test strains. The production of two growth-inhibiting zones could be demonstrated (Fig. 1). One of them seems to be correlated with chlorophyll derivatives. The second zone--larger than the first one--was formed by a fatty acid fraction which was more active in cells harvested in 1973, than in those harvested in 1974. Only a very small cell free zone was found in bioassays of water extracts of H74, presumably caused by chlorophyll derivatives, but there was an area of weak inhibition in H73 as well as in H74.