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

From among 84 marine algae, the green alga, Dunaliella primolecta C-52 5, exhibiting the highest antibiotic activity, was selected. A crude e xtract 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 extrac t of this alga, the antibiotic substance in the algal cells was observ ed as a base-stable, nonprotein material. To purify this antibiotic su bstance, a methanol extract of this alga was eluted successively on a DEAE-Sepharose Cl-6B, silica and Sephadex LH-20 gel column. Three peak s 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 frac tions 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-de grees-C, whereas the activity of fraction Y was unstable above 40-degr ees-C. The above results indicate that algal cells of D. primolecta co ntained a number of different antibiotic substances.