【作者】 王代刚；

【导师】 陈代文；

【作者基本信息】 四川农业大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 本文通过两个试验研究了酵母菌对微量元素锌的富集和酵母锌的生物学效价。 试验一、研究培养基中pH、锌的添加量对酵母菌生长的影响以及锌的添加量与菌体锌富集量的关系，确定酵母锌的最佳培养条件，并测定了酵母锌中有机锌的含量。结果表明：酵母菌富集微量元素锌的最佳培养条件为：培养基起始pH为5.0，锌的添加量为1×10^-2mol／l。在此条件下28-30℃培养120小时后收获菌体，测得菌体锌含量为51000μg／g风干菌体，同时富集锌的95％为有机锌。 试验二、试验用：30日龄SD（Sprague Dawley）大鼠72只，雌雄各半，以硫酸锌为参比标准物，研究了酵母锌的生物学效价。试验共12个处理，每个处理6个重复，每个重复1只大鼠。以酪蛋白、玉米淀粉和蔗糖为基础的缺锌纯合日粮为基础日粮，在纯合日粮基础上分别添加5、10、20、50、100mg锌／kg饲粮的酵母锌和硫酸锌以及20mg锌／kg饲粮的商品酵母锌构成12种试验日粮。耗竭期13天，大鼠自由采食基础饲粮；补锌期8天，饲喂各试验日粮。试验结束时，屠宰大鼠，采集肝脏、胫骨和血清样品，用于测定肝脏、胫骨和血清锌浓度。结果表明：①随日粮锌水平的增加，大鼠的生长性能和肝脏锌、胫骨锌及血清锌的浓度有提高的趋势；②酵母锌对大鼠生长性能和肝脏锌、胫骨锌及血清锌浓度的影响程度大于硫酸锌；③大鼠对酵母锌的真利用率有高于硫酸锌的趋势；④采用斜率比法，以硫酸锌为参比标准物，以肝脏锌和胫骨锌含量为判定指标时，酵母锌生物学效价分别为112.29％和114.64％。更多还原

【Abstract】 Two expriments were conducted to investigate zinc enrichment by yeast and bioavailibity of yeast-zinc.Experiment 1 was to study the effects of pH and zine concentrat ion in form of ZnSO4 7H20 in cuture media on the biomass of yeast and zinc amount accumulated in yeast in order to establish the optimal cultivation conditions for maximum yeast production and zinc enrichment. Zinc distribut ion in yeast cell and the proportion of organic zinc were also quantified. The results show that the culture medium with pH 5.0 and 1x10-2mol Zn2+/L from ZnSO4 7H2O is optimal for maximum yeast output and zinc enrichment. The yeast, cul ti vated in this medium contains 51000 g zinc /g cell, 95% of which is organic zinc.In Experiment 2, 72 thirty- day-old Sprague Dawley rats with half being malewere used to estimate the bioavailability of yeast zinc producted in Exp. 1. Ratswere allotted randomly into 12 dietary treatments with 6 replicates each. Basal diet(Zn content 6. 99mg/kg) based on casein, corn starch and sucrose was supplementedwith 5,10,20,50 or 100 mg Zn 2+ /kg from ZnSO1 or yeast-zinc, or 20 mg Zn/kg fromcommercial yeast-zinc. All rats were fed with basal diet for 13 days, and then withexperimental diets for 8 days. Feces and urine were col lected during the two periodsto determine the endogenous and total zinc exeretions. At the end of experiment, ratswere killed for determining zinc contents in the serum, liver and tibia. The resultsindicate that zinc supplementation from yeast-zinc tends to improve the growthperformance and zinc concentrations in serum, liver, tibia of rats and trueutilization of zinc compared to those fed diels supplemented zinc. with ZnSO4,When zinc concentration in the liver and tibia is used as an indicator and theresponse to ZnSO4 as reference, the bioavailability of zinc from yeast zinc is112.29% and 114.64% respectively based on slope-ratio of regressions of commonlogarithm values of the level of zinc supplementation to zinc concentrations inthe liver and tibia.更多还原