title: An analysis of inter- and intraspecific genetic variabilities in the Kluyveromyces marxianus group of yeast species for the reconsideration of the K. lactis taxon.
abstract: In the present work, we analyse the sequences of the 5.8S rRNA gene and the two internal transcribed spacers 1 and 2 (5.8S-ITS region), obtained from 39 strains belonging to the species Kluyveromyces aestuarii, K. dobzhanskii, K. lactis and K. marxianus, K. nonfermentans and K. wickerhamii, to solve the phylogenetic relationships among these species and also to determine the possible genetic basis for the delimitation of the two currently accepted K. lactis varieties: lactis, including lactose-positive strains isolated from dairy products, and drosophilarum, comprising lactose-negative strains isolated from insects and plant exudates. The determination of the phylogenetic relationships within the species K. lactis, together with the examination of the electrophoretic karyotypes and phenotypic characterization of strains representatives of K. lactis var. lactis and var. drosophilarum, allowed differentiation of two groups of strains. The first, and ancestral, group comprises lactose-negative strains isolated from natural habitats in North America. The second, and derived, group includes both lactose-negative strains isolated from natural habitats in Europe and wine fermentation in South Africa, and lactose-positive strains associated with dairy products. These results suggest that the present taxon K. lactis is a complex of different species, subspecies or, at least, genetically structured populations.
authors.affiliation: Colección Española de Cultivos Tipo (CECT), Universitat de Valencia, Calle Dr Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: Carmela
authors.initials: C
authors.lastname: Belloch
authors.forename: Teresa
authors.initials: T
authors.lastname: Fernández-Espinar
authors.forename: Amparo
authors.initials: A
authors.lastname: Querol
authors.forename: M
authors.initials: M
authors.lastname: Dolores García
authors.forename: Eladio
authors.initials: E
authors.lastname: Barrio
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005060:Europe; D005516:Food Microbiology; D014644:Genetic Variation; D007716:Kluyveromyces / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D009656:North America; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013019:South Africa
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D012340:RNA, Ribosomal, 5.8S