Mode of action of a bacteriocin produced byEnterobacter cloacae DF 13

Abstract

Enterobacter cloacae DF 13 produces a bacteriocin with killing action onKlebsiella edwardsii var.edwardsii. The degree of sensitivity to the bacteriocin depended on the medium in which the cells were grown and on the bacteriocin concentration used. An excess of bacteriocin (60 K.U./ml) arrested growth in about 60 min. Growth of bacteriocin-treated cultures could be restored by trypsin treatment. In Brain Heart Infusion cultures trypsin rapidly restored bacterial growth even after 60 min of bacteriocin treatment. However, in broth cultures and minimal medium cultures treated with bacteriocin for only 10 min, it took 4 to 5 hr before growth started again. The bacteriocin had little effect on resting cells. Broth-grown cells had about 280 and BHI-grown cells about 340 bacteriocin receptor sites. Bacteriocin DF 13 strongly inhibited protein synthesis after a lag-time of 15 to 60 min depending on the concentration used but had no effect on RNA and DNA synthesis nor on respiration and fermentation. The bacteriocin stimulated RNA synthesis in a leucine-deficient mutant after leucine deprivation.