Evidence for a membrane-bound form of a bacteriocin of Bacteroides uniformis Tl-1

The bacteriocin of Bacteroides uniformis T1-1 had previously been reported to have a molecular weight of greater than or equal to 300 000. Reexamination of the B. uniformis bacteriocin revealed that the bacteriocin was found in association with membrane vesicles which had been released by bleb formation from the outer surface of the B. uniformis cells. The bacteriocin could be released from whole cells or purified membrane vesicles by treatment with 6 M guanidine hydrochloride or 7 M urea and had an apparent molecular weight of 5000-6200.