The genus Kluyveromyces is important in dairy industries and lately the pKD1 plasmid as well as the KARS based vectors have proved to be promising instruments in the physiological studies and genetic engineering of dairy yeasts.
Efficient expression vectors have been developed for the yeasts of industrial importance, in particular, the dairy yeasts.
Research has involved:
structural and functional characterization of the plasmid pKD1 and its derivative vectors;
analysis of the mechanism that gives autonomy and stability to the vectors derived from 2 and pKD1;
study of physiological regulation in Kluyveromyces lactis as a production organism.
The molecular structures of the plasmid pKD1 and of the autonomously replicating KARS sequence from K lactis chromosome were established. Plasmid and host functions important for the stable maintenance of the yeast plasmid were examined. Highly stable forms of pKD1 derived vectors were obtained. The host range of pKD1 was extended to several other species of Kluyveromyces. Shuttle deoxyribonucleic acid (DNA) banks were constructed for Kluyveromyces and Saccharomyces species. By combining the K lactis killer toxin gene sequence and pKD1 derived vectors, performing secretion vectors were obtained. Human interleukin-1 beta could be produced at high levels. To better control the gene expression of K lactis, several promoters were studied; in particular, new knowledge was obtained on the regulation of lactose metabolism and in the alcohol dehydrogenase system.