Isolation and characterization of a high molecular weight antibiotic produced by a marine bacterium

Many marine bacteria demonstrate antibiotic activity against organisms of terrestrial origin. Low molecular weight antibiotics have been extracted and, in some cases, purified, but few attempts have been made to isolate high molecular weight antibiotics produced by marine bacteria. In the study reported here, a high molecular weight antibiotic was extracted from whole cells ofAlteromonas strain P18 (NCMB 1890) grown on 2216E medium. Purification included ammonium sulfate precipitation, ultracentrifugation, chromatography on DEAE cellulose, and gel filtration on Ultrogel. A rapid method for measuring specific activity of the antibiotic was developed.