Multilocus analysis reveals large genetic diversity in Kluyveromyces marxianus strains isolated from Parmigiano Reggiano and Pecorino di Farindola cheeses.
In the present study, we have analysed the genetic diversity in Kluyveromyces marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola cheesemaking environment. Molecular typing methods inter-RTL fingerprint and mtDNA RFLPs, as well as, sequence diversity and heterozygosity in the intergenic region between KmSSB1 and KmRIO2 genes and analysis of the mating locus were applied to 54 K. marxianus strains. Inter-RTL fingerprint revealed a large degree of genetic heterogeneity and clustering allowed differentiation of K. marxianus strains from different geographical origins. In general, inter-LTR profiles were more discriminating than RFLPs of mtDNA; however our results also indicate that both techniques could be complementary unveiling different degrees of genetic diversity. Sequence analysis of the intergenic region between KmSSB1 and KmRIO2 genes revealed 26 variable positions in which a double peak could be observed in the sequence chromatogram. Further analysis revealed the presence of heterozygous strains in the K. marxianus population isolated from Parmigiano Reggiano. On the other hand, all strains isolated from Pecorino di Farindola were homozygous. Two very different groups of haplotypes could be observed as well as mixtures between them. Phylogenetic reconstruction divided K. marxianus dairy strains into two separate populations. A few heterozygous strains in an intermediate position between them could also be observed. Mating type locus analysis revealed a large population of diploid strains containing both MATa and MATα alleles and few haploid strains, most of them presenting the MATα allele. Different scenarios explaining the presence and maintaining of homozygous and heterozygous diploids as well as hybrids between them in the Parmigiano Reggiano K. marxianus population are proposed. A principal component analysis supported the large differences between K. marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola.
Faculty of BioSciences and Technology for Food, Agriculture and Environment, University of Teramo, Via C.R. Lerici 1, 64023 Mosciano Sant' Angelo, Italy.
Giuseppe
G
Fasoli
Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Ave. Agustín Escardino 7, 46980 Paterna, Valencia, Spain; Department of Genetics, Universitat de València, C/Dr. Moliner, 56100 Burjassot, Valencia, Spain.
Eladio
E
Barrio
Faculty of BioSciences and Technology for Food, Agriculture and Environment, University of Teramo, Via C.R. Lerici 1, 64023 Mosciano Sant' Angelo, Italy.
Rosanna
R
Tofalo
Faculty of BioSciences and Technology for Food, Agriculture and Environment, University of Teramo, Via C.R. Lerici 1, 64023 Mosciano Sant' Angelo, Italy.
Giovanna
G
Suzzi
Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Ave. Agustín Escardino 7, 46980 Paterna, Valencia, Spain. Electronic address: belloch@iata.csic.es.
Carmela
C
Belloch
D002611:Cheese / Q000382:microbiology*; D004272:DNA, Mitochondrial / Q000235:genetics; D014644:Genetic Variation; D007716:Kluyveromyces / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length
D004272:DNA, Mitochondrial
Genetic diversity; IGS KmSSB1-KmRIO2 sequence; Inter-RTL; Italian dairy; Kluyveromyces marxianus; Mating type; mtDNA RFLPs