Duplication of the beta-galactosidase gene in some Lactobacillus plantarum strains
1999
Fernández, M. | Margolles, A. | Suarez, J.E. | Mayo, B.
Curing of a plasmid that encoded a beta-galactosidase gene (beta-gal) from the Lactobacillus plantarum strain of dairy origin LL441 was 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 as 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.
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