[Production of a photo-sensitive lipid antibiotic by the marine diatom Chaetoceros lauderi (Ralfs) (author's transl)].

A lipid antibiotic was extracted from whole cells of the marine diatom Chaetoceros lauderi (Ralfs) and roughly identified as an unsaturated fatty acid by thin layer chromatography. A number of Gram-positive terrestrial bacteria and several Gram-negative marine bacilli were sensitive to this antibiotic, whereas Gram-negative enteric bacteria were resistant. Solar irradiation led to its partial disappearance and to the production of more polar antibiotics with a stronger antibacterial activity. This observation is compared to similar data culled from literature, and its significance in a natural environment is discussed.