Genetic and molecular study of the inability of the yeast Kluyveromyces lactis var. drosophilarum to ferment lactose |
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Authors: | G I Naumov E S Naumova E Barrio A Querol |
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Institution: | (1) State Research Institute of Genetics and Selection of Industrial Microorganisms, Pervyi Dorozhnyi proezd 1, Moscow, 117545, Russia;(2) Instituto Cavanilles de Biodiversitat i Biologia Evolutiva, Paterna, 46071, Spain;(3) Instituto de Agroquimica y Tecnologia de los Alimentos, Burjassot, 46100, Spain |
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Abstract: | The fermentation of lactose (Lac+) in the dairy yeast Kluyveromyces lactis var. lactis is controlled by the LAC4 (β-galactosidase) and LAC12 (lactose permease) genes. The complementation analysis of twelve Kl. lactis var. drosophilarum natural homothallic Lac? strains of different origin was carried out using the genetic heterothallic lines of Kl. lactis var. lactis of the lac4LAC12 and LAC4lac12 genotypes. It was shown that the natural Lac? strains did not possess the LAC4LAC12 gene cluster. Southern hybridization of chromosomal DNA with LAC4 and LAC12 probes, as well as recombination analysis, showed that Kl. lactis var. drosophilarum yeasts do not have even silent copies of these genes. As distinct from this yeast, natural Lac? strains of the yeast Kl. marxianus are mutants impaired in the lactose permease gene (lac12 analogue), but possess an active β-galactosidase gene (LAC4 analogue). The origin of the LAC4LAC12 gene cluster of the dairy yeasts Kl. lactis is discussed. |
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Keywords: | dairy yeast Kluyveromyces lactis var lactis Kluyveromyces lactis var drosophilarum Kluyveromyces marxianus LAC4 and LAC12 genes b-galactosidase lactose permease |
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