Evidence for association of bacteriocinogenic activity with membrane vesicles of Thermus rubens

Thermus rubens has previously been reported to exhibit bacteriocin-like antagonism against other members of the genus Thermus when assayed via the deferred antagonism technique. Bacteriocin activity was not detectable in various age batch culture supernatants assayed by simple spotting procedures. Successful cell-free isolation was accomplished by way of a procedure employing French press disruption of T. rubens cells. Ultrafiltration and molecular exclusion chromatographic studies ascribed a high molecular weight to the agent which was found to be completely precipitable by ammonium sulphate. Activity was totally sedimentable upon ultracentrifugation. Transmission electron microscopic examination of column fractions containing high specific activity revealed numerous circular, apparently trilaminar, structures indicative of membrane vesicles.