ANTIBIOTIC SUBSTANCES PRODUCED BY A MARINE GREEN-ALGA, DUNALIELLA-PRIMOLECTA

From among 84 marine algae, the green alga, Dunaliella primolecta C-525, exhibiting the highest antibiotic activity, was selected. A crude extract from this alga strongly inhibited the growth of Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and Enterobacter aerogenes. From experiments on pH, solvent, and an inhibitor of the crude extract of this alga, the antibiotic substance in the algal cells was observed as a base-stable, nonprotein material. To purify this antibiotic substance, a methanol extract of this alga was eluted successively on a DEAE-Sepharose Cl-6B, silica and Sephadex LH-20 gel column. Three peaks exhibiting antibiotic activity from the final column were observed, indicating peak No.1 to have a molecular weight of over 1300 and peaks Nos 2 and 3 to have molecular weights of about 300-400. The main fractions X, Y and Z of the three peaks were investigated for temperature stability. The activities of fractions X and Z were stable up to 80-degrees-C, whereas the activity of fraction Y was unstable above 40-degrees-C. The above results indicate that algal cells of D. primolecta contained a number of different antibiotic substances.