Abstract
An antibiotic factor obtained from Alteromonas luteoviolacea was shown to kill Paramecium caudatum. This substance was shown to be destroyed by boiling, sonication, or freezing. It passed through a 0.45-micron-pore-size filter and was not precipitated from a culture supernatant with ethyl alcohol. Its production varied with A. luteoviolacea strains and medium constituents. It was also shown to be distinct from the A. luteoviolacea antibiotic that affects bacterial cells.