Bacteriocins: Unique approaches for the characterization of peptide antimicrobials in lactic acid bacteria

Study and conclusions. Curvaticin FS47 is a listeria-active peptide produced by L. curvatus that was isolated from retail meats. The nucleotide sequence spanning the 9.6kb operon of curvaticin FS47 was determined from the original clones, shortened subclones and the vectorette PCR method. Sequence analysis of the 9.6-kb curvaticin operon revealed the presence of several genes related to bacteriocin biosynthesis. Two types of bacteriocins were identified, (i) a two component bacteriocin (T alpha and beta subunits) and (ii) a single component bacteriocin (curvaticin FS47). There is high homology between the bacteriocin gene clusters of L. curvatus FS47 and L. sakei.; A major concern in using bacteriocins as food preservatives is the occurrence of natural or spontaneous resistance. Here, L. monocytogenes 39-2 and BacR variants derived from it, were used as indicator strains to screen for bacteriocin-producing LAB from food samples and these bacteriocins were then categorized into different 'resistance classes' based on their ability to inhibit these spontaneously-acquired bacteriocin resistant mutants. The use of a mixture of bacteriocins from different 'resistance classes' would have greater likelihood to overcome spontaneous resistance.; Bacteriocin producing LAB belonging to different resistance classes were subjected to a bacteriocin-specific PCR array with primers for forty-two known structural genes of bacteriocins from LAB. Amplimers obtained were sequenced and the sequence analysis determined if the bacteriocin was novel or already existed in the GenBank database. This approach allowed for the quick and facile discovery of functionally new bacteriocins among LAB.; A combination of bacteriocins belonging to the 3 different 'resistance classes' were used to perform an inhibitory assay against L. monocytogenes 39-2. The results show a significant difference in treatment that was sufficient to prevent regrowth of Listeria for an extended period of time.