[Studies to investigate the ecological importance of the mass development of Hydrodictyon reticulatum in infiltration basins for drinking water. I. Metabolic products and their effect on various types of bacteria (author's transl)].

Cells of the green freshwater alga H. reticulatum, harvested from their natural habitat, were found to have antibacterial activity. The active substances seem to be lipophilic, because ethanol extracts were more effective, especially against Bac. subtilis, than water extracts (Table 4). The different effects of water extracts, which were tested after various dilution steps (Table 1--3) presume, that there must be a second active substance. We suppose, that it is correlated with chlorophyll derivatives. Culture filtrate from a strain, grown under laboratory conditions, was tested in the same way. Concentrated tenfold it was active against several grampositive strains of bacteria.