Heterologous expression of enterocin AS-48 in several strains of lactic acid bacteria

[Aims] Enterococcus faecalis produces a cationic and circular enterocin, AS-48, of 7149 Da, the genetic determinants of which are located within the pMB2 plasmid. We have compared enterocin AS-48 production by different enterococci species with that of other `safe' lactic acid bacteris (LAB) (GRAS status) and looked into the subsequent application of this enterocin in food production.[Methods and Results] In an effort to exploit this system for the heterologous expression of enterocin AS-48, a number of vectors containing the as-48 cluster were constructed and used to transform several LAB strains (genera Enterococcus, Lactococcus and Lactobacillus).[Conclusion] Heterologous production of enterocin AS-48 failed when bacteria other than those belonging to the genus Enterococcus were used as hosts, although expression of a partial level of resistance against AS-48 were always detected, ruling out the possibility of a lack of recognition of the enterococcal promoters.[Significance and Impact of the Study] Our results reveal the special capacity of species from the genus Enterococcus to produce AS-48, an enterocin that requires a post-transcriptional modification to generate a circular peptide with a wide range of inhibitory activity against pathogenic and spoilage bacteria. Preliminary experiments in foodstuffs using nonvirulent enterococci with interesting functional properties reveal the possibility of a biotechnological application of these transformants.This study was supported by the Spanish Dirección General de Investigación Científica y Técnica (Project BIO98-0908-CO2-01) and Grupo de Investigación de la Junta de Andalucía (CIV 016). M. Fernández received a fellowship from the Spanish Ministry of Education, Culture and Sports.Peer reviewe