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Biotechnology (N Y). 1991 Jan;9(1):70-3.

Isolation and characterization of carotenoid hyperproducing mutants of yeast by flow cytometry and cell sorting.

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Department of Food Microbiology and Toxicology, University of Wisconsin, Madison 53706.


The carotenoid pigment astaxanthin (3,3'-dihydroxy-beta,beta-carotene-4,4'-dione) is an important component in feeds of aquacultural animals. It is produced as a secondary metabolite by the yeast Phaffia rhodozyma, and the isolation of rare mutants that produce increased quantities is limited by the lack of genetic selections. As a model system for enriching mutants increased in production of secondary metabolites, we have used quantitative flow cytometry/cell sorting (FCCS) to isolate astaxanthin hyperproducing mutants of the yeast. Experimental conditions were developed that gave a quantitative correlation of fluorescence and carotenoid content. In mutated populations, a 10,000-fold enrichment of carotenoid-overproducing yeasts was obtained. Distinctive differences were detected by FCCS in fluorescence and forward scatter values of mutant and wild-type populations of yeasts. Comparison of wild-type and mutant clones by fluorescence confocal laser microscopy showed that the mutants had more intense fluorescence throughout the cell than the wild-type. Quantitative FCCS is a sensitive method to isolate and characterize carotenoid overproducing mutants and should be useful as a general method for the isolation of mutants increased in other fluorescent metabolites.

[Indexed for MEDLINE]

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