title: Genetic diversity in the lactose operons of Lactobacillus helveticus strains and its relationship to the role of these strains as commercial starter cultures.
abstract: Two novel insertion sequence elements, ISLhe1 and ISLhe15, were located upstream of the genes encoding the beta-galactosidase enzyme in Lactobacillus helveticus commercial starter strains. Strains with the IS982 family element, ISLhe1, demonstrated reduced beta-galactosidase activity compared to the L. helveticus type strain, whereas strains with the ISLhe15 element expressed beta-galactosidase in the absence of lactose.
authors.affiliation: Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, County Cork, Ireland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Callanan
authors.forename: T P
authors.initials: TP
authors.lastname: Beresford
authors.forename: R P
authors.initials: RP
authors.lastname: Ross
mesh_terms: D001483:Base Sequence; D002611:Cheese / Q000382:microbiology*; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D021901:DNA, Intergenic; D005516:Food Microbiology; D005524:Food Technology; D014644:Genetic Variation; D007763:Lac Operon; D007778:Lactobacillus / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D021901:DNA, Intergenic