Production of Enriched Biomass by Carotenogenic Yeasts - Application of Whole-Cell Yeast Biomass to Production of Pigments and Other Lipid Compounds

Yeasts are easily grown unicellular eukaryotes. They are ubiquitous microorganisms, occuring in soil, fresh and marine water, animals, on plants and also in foods. The environment presents for yeast a source of nutrients and forms space for their growth and metabolism. On the other hand, yeast cells are continuously exposed to a myriad of changes in environmental conditions. These conditions determine the metabolic activity, growth and survival of yeasts. Basic knowledge of the effect of environmental factors on yeast is important for understanding the ecology and biodiversity of yeasts as well as for control the yeast physiology in order to enhance the exploitation of yeasts or to inhibit or stop their harmful and deleterious activity. The overproduction of some metabolites as part of cell stress response can be of interest to the biotechnology. For instance carotenogenic yeasts are well known producers of biotechnologically significant carotenoid pigments astaxanthin, ┚-carotene, torulen, torularhodin and under stress conditions this carotenoid accumulation was reported to be increased. Knowledge of molecular mechanism of the carotenoid production stimulation can then lead to improvement of such biotechnological process. Red yeasts are able to accumulate not only carotenoids, but also ergosterol, unsaturated fatty acids, Coenzyme Q10 and other, which can contribute to the biomass enrichment. The use of this stressed biomass in feed industry could have positive effect not only in animal and fish feeds because of high content of physiologically active substances, but it could influence nutritional value and organoleptic properties of final products for human nutrition. Yeast biomass, mainly in the form of Saccharomyces cerevisiae, represents the largest bulk production of any single-celled microorganism throughout the world. In addition to use of