Antibacterial activity of different Zymomonas mobilis strains.

Twenty different Zymomonas mobilis strains were found to produce a substance which inhibited or killed various other Zymomonas , Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa strains. This antibacterial activity could be detected in cross-streak tests and as zones of clearing in lawns of the test bacteria. When Zymomonas strains are used as recipients in conjugation experiments, their antibacterial activity can be used to advantage for removal of unwanted donor cells from the mating mixtures.