Study On Breeding Of High Hield Chromium-enriched Yeast With Compound Inducing Mutation

Chromium is a necessary trace element in organism being provided with much function. GTF(glucose tolerance factor ) is a required ingredient maintaining natural glucose level in animal blood. But inorganic chromium have a little absorptivity and great toxicity. Yeast can sorb trace element greatly, so can become favorable carrier of it. The yeast can transform inorganic chromium to organic of it, improving its assimilated rate and reduce toxicity. Yeast contain very much protein and VB, so it is favorable microorganism protein feed. A good strain is a key for high yield Cr-enriched yeast, the experiment prepare a over-chromium yeast by compound mutation and search for optimal incubate condition of it.The experiment take Candida tropicalis 1254 as original straits, N+ implantation inducing parameter is energy 20Kev ,dose 0～20×2.6×1014N+/cm2 N+, getting a mutation Y-6 with strong tolerance for Cr+ and stabilization transmissibility by Cr concentration tonsure flab. The results showed that biomass and chromium content increasing from 0.525ug/100mL,562ug/g increasing to 0.905ug/100mL,829ug/g. Through single factor experimentation fish out Y-6 optimal culture condition: optimal culture medium :1% yeast powder, peptone maltose, distilled water, culture medium Cr content 800ug/mL, beginning pH 5.0 ,10% inoculate quantity, temperature 30℃, culturing 24h. Under the condition the preparation for Cr-enriched yeast have optimal effect. This chromium-enriched yeast technique settle a base for industrialization production. The results show N+ implantation is a sort of chromium-enriched yeast breeding method.The results of biological effects that the yeast cell Candida tropicalis were implanted by N+ were as following: implantation can damnify cell, the survival rate cure is a saddle model, namely early decreasing, then increasing, again decreasing at last. SEM indicated that the control were integrity. While the surface of cell be implanted was coarse. Moreover, the damage of ionic etching and phenomenon of dilapidating cell wall could be seen. When implanted dose increased continually, the damage to cells became more and more serious. After culture, the yeast colony and microscopical cell shape is different distinctly.The experiment determine the organic and inorganic Cr-content, and find that the mutated strains Y-6 organic Cr content is 94.6% but original one is 85%, The absorption peaks of organic chromium were at 260 nm by using ultraviolet. The amino-acid analysis show that the former amino-acid content more than the latter, especially the contents of lysine,methio—nine,leucine,isoleucine.