title: Insertion sequence elements as mediators of strain diversity in Lactobacillus helveticus.
abstract: Insertion sequence (IS) elements were found to be associated with the truncation of predicted cellobiose transport, acetaldehyde dehydrogenase and diacetyl reductase genes in the genome of Lactobacillus helveticus DPC 4571. The conservation of the IS elements in these different genomic locations among L. helveticus cheese isolates was determined by amplification with gene-specific and IS element-specific primers. The presence of two of the IS elements was found to follow a genotypic profile of the strains generated by randomly amplified polymorphic DNA (RAPD)-PCR and strains that clustered by RAPD-PCR tended to have the IS element in the same position. However, the IS element that interrupted the cellobiose transport gene was found to be common to all strains tested. This conserved genotype suggests the insertion event occurred early in the evolution of L. helveticus as a separate species.
authors.affiliation: Teagasc, Moorepark Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Callanan
authors.forename: R P
authors.initials: RP
authors.lastname: Ross
authors.forename: T P
authors.initials: TP
authors.lastname: Beresford
mesh_terms: D001483:Base Sequence; D002611:Cheese / Q000382:microbiology*; D016000:Cluster Analysis; D017124:Conserved Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics*; D005784:Gene Amplification; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D052198:Lactobacillus helveticus / Q000235:genetics*; D008969:Molecular Sequence Data; D019105:Random Amplified Polymorphic DNA Technique; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial