title: Duplication of the beta-galactosidase gene in some Lactobacillus plantarum strains.
abstract: Curing of a plasmid that encoded a beta-galactosidase gene (beta-gal) from the Lactobacillus plantarum strain of dairy origin LL441 was not accompanied by complete loss of the lactose utilization phenotype. DNA-DNA hybridization, using an internal fragment of the beta-gal gene as a probe, revealed a second determinant located on the chromosome of the cured derivatives. The chromosomal copy was present in all of a series of beta-Gal+ L. plantarum and Lactobacillus pentosus strains from different origins. In addition, four other L. plantarum strains harboured plasmid encoded beta-gal genes as well. Since both sequences cross-hybridized and present a similar genetic organization, it is postulated that the plasmid copy was generated through gene duplication and, probably, selected by growth of the strains in lactose rich environments.
authors.affiliation: Area de Microbiología, Departamento de Biología Funcional, Universidad de Oviedo, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Fernández
authors.forename: A
authors.initials: A
authors.lastname: Margolles
authors.forename: J E
authors.initials: JE
authors.lastname: Suárez
authors.forename: B
authors.initials: B
authors.lastname: Mayo
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry; D003612:Dairying; D004926:Escherichia coli; D005285:Fermentation; D007778:Lactobacillus / Q000201:enzymology* / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D015183:Restriction Mapping; D001616:beta-Galactosidase / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D001616:beta-Galactosidase