Multi-Mutated Breeding Of Resistant Strain Of Saccharomyces Cerevisiae To Chromium With Protoplast And Investigation Of Its Biological Function

Chromium is one of the essential trace elements and the most important component of glucose tolerance factor (GTF). In human bodies, lack of chromium can cause obstacle in metabolism of glucose, lipid and protein, lead to several diseases, such as arteriosclerosis, diabetes, coronary disease, twig neuritis and myopia, etc. In animals, lack of chromium brought on cholesterol and blood sugar increased, growth retarded, immunity decreased, reproduce ability declined and life-span shortened. When chromium was abundant, those symptoms did not appear. Different forms of chromium have different combinability in tissues, which causes different absorptivity. The inorganic chromium was highly toxic and absorbed in very low level while the organic chromium was rapidly and safely absorbed with the absorptivity reaching 10%-25%.In organic chromium preparations, chromium-enriched yeast has higher biological activity, lower toxicity, and lower costs in production than any others. As an important component of the medicament to prevent and treat diabetes, chromium-rich yeast had attracted huge attentions. Besides, the biology active substances in yeast cell had sanitarian effect to organisms, too. Inorganic chromium can be translated into organic chromium by yeast; it's so called the'microorganism element carrier'. So, production of chromium-enriched yeast has great importance in application. As the enrichment ability of chromium in common Saccharomyces cerevisiae is very limited, our purpose of this research is to breed a new strain of Saccharomyces cerevisiae having higher chromium enrichment ability by multi-mutagenesis breeding with protoplast, and then apply it to production.After the original strain Saccharomyces cerevisiae SY8 was haploided, the resistance level was determined to select resistant strains. A strain named SY8-6 whose Cr3+ resistant level was 5mmol/L was obtained. Then it was lysised to get rid of cell wall by snailase. During that, the optimum conditions of forming and regeneration of protoplasts were researched:0.8mol/L NaCl as...