GENETIC CHARACTERIZATION OF LF221 ACIDOCINS

Abstract

Acidocin LF221 A and B are at least two different bacteriocins produced by Lactobacillus acidophilus LF221. In previous research work the N-terminal amino acid (AA) sequence was determined from the purified peptides and probes for both acidocins were prepared as well. Southern hybridization was used to locate structural genes for acidocin LF221 A and B on the genome. Using as a template digested chromosomal DNA of either LF221 or its bac^- derivative, identical results were obtained. A possible explanation for this is that bac^- mutant still contains the structural genes for both acidocins. When acidocin LF221 A or B were compared to other known bacteriocins, they showed some homology to ThmB peptide of thermophilin 13 or LafX peptide of lactacin F. We assume that LF221 acidocins are novel representatives of the class II bacteriocins.