IS Lpl1 Is a Functional IS 30 -Related Insertion Element in Lactobacillus plantarum That Is Also Found in Other Lactic Acid Bacteria

Abstract

ABSTRACT We describe the first functional insertion sequence (IS) element in Lactobacillus plantarum . IS Lpl1 , an IS 30 -related element, was found on the pLp3 plasmid in strain FB335. By selection of spontaneous mutants able to grow in the presence of uracil, it was demonstrated that the IS had transposed into the uracil phosphoribosyltransferase-encoding gene upp on the FB335 chromosome. The plasmid-carried IS element was also sequenced, and a second potential IS element was found: IS Lpl2 , an IS 150 -related element adjacent to IS Lpl1 . When Southern hybridization was used, the copy number and genome (plasmid versus chromosome) distribution data revealed different numbers and patterns of IS Lpl1 -related sequences in different L. plantarum strains as well as in Pediococcus strains. The IS Lpl1 pattern changed over many generations of the strain L. plantarum NCIMB 1406. This finding strongly supports our hypothesis that IS Lpl1 is a mobile element in L. plantarum . Database analysis revealed five quasi-identical IS Lpl1 elements in Lactobacillus , Pediococcus , and Oenococcus strains. Three of these elements may be cryptic IS, since point mutations or 1-nucleotide deletions were found in their transposase-encoding genes. In some cases, IS Lpl1 was linked to genes involved in cold shock adaptation, bacteriocin production, sugar utilization, or antibiotic resistance. IS Lpl1 is transferred among lactic acid bacteria (LAB) and may play a role in LAB genome plasticity and adaptation to their environment.