The Preparation Of Copper-Enriched Yeast And Its Application In Rats

Three experiments were conducted to investigate the properties of two yeasts, the suitable conditions for yeast to enrich copper and the utilization effect of copper-enriched yeast in Rats.Exp 1 aims to select the more suitable yeast for preparing copper-adapted yeast by comparing the properties of two species of yeast,Candida sp and Saccharomyces cerevisiae.The trial compared these two yeasts from their growth properties,the effect of different initial pH and copper concentration in medium.The results suggested that Candida sp can adapt lower pH and grow well in 50 mg/L copper condition in comparison with the Saccharomyces cerevisi(?)e,indicating that Candida sp is more suitable to prepare copper-adapted yeast.Exp2 is to improve the capacity of Candida sp to tolerate high copper concentration in culture medium and prepare copper-enriched yeast.Candida sp was cultured in the medium increasingly added 50,100,150,200,250,300,350 and 400 mg/L of copper to improve tolerance to high copper.Then the culture conditions were optimized.The results showed that yeast cultured in sucrose medium with initial pH 5.5,copper concentration 300 mg/L for 60h in medium contained copper 16.65 mg/g.The yeast production was 6.73g/L.Copper-enriched yeast was then produced under production line. The product contained copper and yeast production were 16.47mg/g and 15.05g/L respectively.Exp 3 studied on the utilization of different copper sources for rats.Sixty-six Wistar female rats weighted 60～90g were randomly allotted into 11 treatments with 6 replications each in a simple factorial experimental arrangement design.10,30,60,100 or 250 mg/kg copper either from copper-enriched yeast or copper sulfate were added into the purified basal diet.The trial duration was 10 days after 12-days depletion period.The results suggested that:1) Liver and shinbone copper content were decreased by 51.2% and 17.6%respectively,and ceruloplasmin content in serum was reduced from 80.98U/L to 6.07 U/L after depletion period.2) ADG and ADFI were increased by 2.5%and 3.5% respectively in copper-yeast treatments in comparison with copper sulfate treatments,but there were no significant difference between copper resources and among levels and copper resources×levels for ADG or ADFI.3) There were extremely significant differences on ceruloplasmin,Cu Zn-SOD,liver copper content between copper resources and among copper levels and copper resource×copper level.The conclusion was that two different copper sources had no effect on the growth performance of rats, but copper-enriched yeast at levels of 60 mg/kg and 100 mg/kg had better effects on the copper content in organ and serum biochemical indicators than sulfate copper.The conclusion shown that copper-adapted('andida sp cultured in sucrose medium with initial pH 5.5.copper concentration 300 mg/L and temperature 28～30℃for 60h in sucrose medium can produce copper-enriched yeast product with copper content 16.47 mg/g and higher utilization efficiency.