Identification and purification of a protein that induces production of the Lactobacillus acidophilus bacteriocin lactacin

Study of the influence of mixed cultures on the production of lactacin B, a heat-stable bacteriocin produced by Lactobacillus acidophilus N2, shows that associated cultivation with the sensitive indicator, Lactobacillus delbrueckii subsp. lactis ATCC4797, increases lactacin B production. Indicator cells increase the production of lactacin B and a French pressure cell disrupts the indicator cells generating cell-free filtrates with inducing activity. Chromatographic and gel filtration experiments of cell-free filtrates yield a protein which induces lactacin B production while gel electrophoresis and protein sequencing help characterize the protein.