Browse chromosome features: Click on a 50 kbp segment.The natural habitat of Kluyveromyces lactis is diverse, but many strains were originally isolated from milk-derived products. At present, two varieties in K. lactis have been defined by taxonomists: K. lactis (Dombrowski) van der Walt var. lactis (1986) and K. lactis (Dombrowski) van der Walt var. drosophilarum (1986) . The former can assimilate lactose while the latter does not.
General information, lifestyle, ecological niche
K. lactis is a scientifically and biotechnologically non-Saccharomyces important yeast.
Although it is an ascomycetous budding yeast closely related to S. cerevisiae, K. lactis has become an attractive alternative model owing to distinct metabolic and physiological properties. It is a Crabtree-negative aerobic respiro-fermentative yeast, which can accommodate a wide range of carbon sources such as lactose and other respiratory substrate .
Biogenesis of its respiratory system is not sensitive to glucose repression but K. lactis also ferments glucose to ethanol in aerobic conditions. Industrial interests also stimulate research on K. lactis since it is able to grow to a high cell density and to secrete heterologous proteins efficiently.
Highlights of genetic and genomic results
K. lactis is usually grown in standard yeast medium at an optimal temperature of 28°C. Its life cycle is essentially similar to that of S. cerevisiae, except that diploids are not stable and sporulate rapidly. K. lactis is amenable to genetic studies using conventional techniques such as crossing and tetrads analysis, gene targeting, integrative and replicative transformation.
Electrophoretic karyotyping and genome sequencing distinguishes six chromosomes ranging in size from about 1 to 3 Mb .
The genome size is 10.6 Mb long (without the rDNA) with approximately 5,300 CDS and 162 tRNA genes. Mitochondrial DNA is a circular molecule with a length of about 40 kb . Some strains contain a pair of cytoplasmic linear DNA plasmids, pGKL1 (8.8 kb) and pGKL2 (13.4 kb), conferring the killer phenotype . A 2µ-like plasmid, pKD1 (4757 bp) has been isolated in some K. lactis strains and a variety of plasmid vector systems, including low/high shuttle plasmids, are also available.
- Lachance, M.-A., Current status of Kluyveromyces systematics. FEMS Yeast Research, 2007. 7(5): p. 642-645.
- Wésolowski-Louvel, M., K.D. Breunig, and H. Fukuhara, Kluyveromyces lactis. In: K. Wolf, editor. Non-conventional yeast in biotechnology. Heidelberg: Springer- Verlag, 1996: p. 139-201.
- Breunig, K.D., et al., Regulation of primary carbon metabolism in Kluyveromyces lactis. Enzyme Microb Technol, 2000. 26(9-10): p. 771-780.
- Gonzalez-Siso, M.I., et al., Respirofermentative metabolism in Kluyveromyces lactis: Insights and perspectives. Enzyme Microb Technol, 2000. 26(9-10): p. 699-705.
- van Ooyen, A., et al., Heterologous protein production in the yeast Kluyveromyces lactis. FEMS Yeast Research, 2006. 6(3): p. 381-392.
- Schaffrath, R. and K.D. Breunig, Genetics and molecular physiology of the yeast Kluyveromyces lactis. Fungal Genet Biol, 2000. 30(3): p. 173-90.
- Sor, F. and H. Fukuhara, Analysis of chromosomal DNA patterns of the genus Kluyveromyces. Yeast, 1989. 5(1): p. 1-10.
- Dujon, B., et al., Genome evolution in yeasts. Nature, 2004. 430(6995): p. 35-44.
- Zivanovic, Y., et al., Complete nucleotide sequence of the mitochondrial DNA from Kluyveromyces lactis. FEMS Yeast Research, 2005. 5(4-5): p. 315-322.
- Chen, X.J., et al., Sequence organization of the circular plasmid pKD1 from the yeast Kluyveromyces drosophilarum. Nucleic Acids Res, 1986. 14(11): p. 4471-81.
- Chen, X.J., Low- and high-copy-number shuttle vectors for replication in the budding yeast Kluyveromyces lactis. Gene, 1996. 172(1): p. 131-6.