pRS4: UN VECTOR DE CLONACIÓN IDÓNEO PARA BACTERIAS ÁCIDO-LÁCTICAS DE USO ALIMENTARIO pRS4: AN APPROPRIATE CLONING VECTOR FOR LACTIC-ACID BACTERIA OF FOOD USE

Abstract Resumen The ability of pRS4, a cryptic plasmid from Pediococcus pentosaceus, as a selective cloning vector for lactic acid bacteria has been analysed. The results indicate that pRS4C1, a cloning vector from pRS4 can stably transform Lactobacillus plantarum, Pediococcus acidilactici and P. pentosaceus (three lactic acid bacteria used as starters in the food industry) but it does not transform Enterococcus faecalis (a lactic acid bacteria which is undesirable due to its potential origin, mainly of faecal source). Further modifications of the pRS4C1, consisting in positional changes of the chloramphenicol resistance marker and/or single mutation into the initiation codon of the gene of the replication protein, does not generate expression of pRS4 into E. faecalis, however the ability of these derivates to transform Lactobacillus and Pediococcus remains unaltered. These results indicate that pRS4 can be used as a selective cloning vector for genetic manipulation of useful lactic acid bacteria, withou...