Effect of Filtrates from Cultures of Unicellular Algae or the Growth of Staphylococcus aureus.

Filtered culture solutions from cultures of different unicellular algae, especially Chlorella vulgaris, were tested for content of growth affecting substances using the bacteria Staphylococcus aureus as test organism. Either a decrease or an increase of the growth of the bacteria could be found. It was observed that both growth accelerating and growth inhibiting substances were present simultaneously in the culture solution and that the concentration of the substances varies a great deal in cultures of the same algal species even if the cultures were grown under apparently identical conditions. In one of the experiments the inhibiting effect was decreased by heating the algal filtrate at 70°C for 20 min. In another experiment at least two inhibitors were found. One was inactivated by illumination of the algal filtrate, a second was absorbed to Norit. [ABSTRACT FROM AUTHOR]