酵母对硒元素的富集研究和改良策略

<正>硒在自然界中以无机硒和有机硒两种形式存在。与无机硒相比,有机硒具有吸收率高、生物活性强、毒性低、环境污染小等特点。有机硒可由人工合成,也可通过生物转化和生物富集等不同方式生产。目前较为广泛采用的是酵母菌富集法,即利用酵母菌对无机硒进行富集和生物有机化,生产富硒酵母。     

优良酵母菌株的分离和筛选

试验采用麦芽浸粉培养基和秸秆粉培养基,利用平板划线法,从富含酵母菌的青贮饲料和酒糟饲料中分离出酵母菌,经过培养条件的优化,从中筛选出用作反刍动物饲用的优良酵母菌株。试验结果表明,从青贮玉米和大麦啤酒糟中分离得到9号菌株生物产量最高,OD值为2.231,为优良酵母菌株。     

产胡萝卜素酵母菌的筛选

为获得具有开发应用价值的产胡萝卜素的酵母菌株,本研究从自然界中共采集了35个土样,经过富集、涂布、划线分离、种子培养和发酵培养后,采用二甲基亚砜和丙酮以1:3的比例进行破壁提取,并对色素提取物进行紫外扫描定性、定量分析,得到7株酵母菌株符合试验要求,并筛选出胡萝卜素产量最高的菌株,编号为21-1,产量为7.42 mg/L。对此菌株进行无机盐组分单因素试验和正交试验的初步优化,优化后21-1菌株胡萝卜素产量为8.55 mg/L,相比初筛的菌种提高了15.3%。将这7株菌株产胡萝卜素的特征吸收峰与β-胡萝卜素标准品进行对比发现,其中一种含量为β-胡萝卜素。[关键词] 胡萝卜素|酵母菌|发酵优化     

有机硒和无机硒对肉用仔鸡性能的影响

所有各种动物的日粮中都必须加入必需微量元素以保持动物的健康、生长和生化生理功能。谷胱甘肽过氧化物酶含有相当量的硒作为其组成部分,表明了硒这一必需微量元素所具有的生化作用,同时也可据此来监测各种动物的硒状态。人们对于硒在生化系统的作用尚无充分了解,但...     

有机硒同羽毛生长和企业利润的关系

作为对硒源效能评价工作的一部分,必须对鸡的外表进行观察。在春季试验的早期观察到有些肉鸡看来具有较多的羽毛。这一现象是未曾预料到的,其原因尚有待研究。早在１９６６年就已有人报告了硒与鸡的羽毛生长和羽毛发育之间的关系。为了更好地理解硒的这一功能以及理解硒...     

筛选酵母菌提高肉鸡生长速度和品质的研究

在从鸡肠道中成功分离出一株动物内源酵母菌的基础上,对其进行了高密度发酵培养研究,获得了OD680nm为48.1的酵母菌发酵液。通过将酵母菌发酵液饲喂肉鸡,研究了其对肉鸡生长和鸡肉品质的效应。结果表明,每天每只鸡通过饮水饲喂0.5mL酵母菌,在肉鸡的一个饲养周期42天内,每只肉鸡的平均重量比对照组多增重193g,增重率达7.7%,其中公鸡多增重163g,增重率为5.9%;母鸡多增重224g,增重率为9.9%,说明酵母菌对母鸡的增重效果要好于公鸡。同时发现,投喂酵母菌后,可以将肉鸡的料肉比从1.685降低到1.567,降低率达7.0%。进一步研究发现,饲喂酵母菌的鸡肉品质有明显提高,其中粗蛋白含量、总游离氨基酸含量、必需氨基酸含量和风味氨基酸含量分别比对照组提高了4.0%、23.6%、4.2%和32.0%,说明投喂酵母菌不仅可以显著提高肉鸡的生长速度、降低料肉比,而且可以大幅度提高鸡肉的品质和风味。     

益生性酵母菌的筛选与鉴定

采用YPD平板从青海牦牛瘤胃和西藏青稞酒糟中筛选酵母菌,并对其进行形态学、分子生物学特性、生理生化特性和益生特性鉴定.试验结果表明:从青海牦牛瘤胃中筛选到马克斯克鲁雏酵母菌3株,从西藏青稞酒糟中筛选到酿酒酵母菌4株,毕赤酵母菌2株,其中毕赤酵母菌JZ10起酵时间短,环境适应性强,有广泛的药物敏感性且对金黄色葡萄球菌和沙...     

瘤胃酵母菌的筛选及应用研究进展

酵母菌含有丰富的菌体蛋白质和二十多种氨基酸,是动物机体所需优质蛋白质和氨基酸的重要来源,且含有极为丰富的维生素E和B族维生素,有利于满足反刍动物的全价营养需要,促进其生长发育。此外,酵母菌还有平衡瘤胃的微生物区系、减少甲烷等有害气体的产生、稳定瘤胃pH等功能。酵母菌制剂可促进动物的生长发育、改善机体的消化机能、加强动物的免疫力,因而在畜牧业中作为纯天然的饲料添加剂而被广泛应用。该文主要从瘤胃源酵母和酵母菌制剂对反刍动物瘤胃内环境的调控作用、影响机制及其生理功能等方面进行了综述,以期为后续的科研工作和实际生产提供一定的参考依据。     

酵母菌产纤维素酶的发酵条件研究

利用单因素试验和正交设计方法研究秸秆、麸皮、蛋白胨和酵母膏含量及起始pH等不同条件对酵母菌FWZ8-12产纤维素酶的影响。研究结果表明:在这些影响因素中,秸秆添加量对纤维素酶产量影响最大。培养基中秸秆0.8%、麸皮5%、蛋白胨0.25%和酵母膏0.2%,发酵起始pH为6,30℃发酵培养24h后,纤维素酶活力22.45U较优化前提高了1.9倍。     

有机硒和维生素E对母猪生产性能的影响

试验采用随机区组设计,2×2因子设计,在相同的日粮基础上,妊娠期和哺乳期分别添加0.3 mg/kg亚硒酸钠(以硒计)+22 IU/kg VE0、.3 mg/kg酵母硒(以硒计)+22 IU/kgVE0、.3 mg/kg亚硒酸钠(以硒计)+44 IU/kg VE、0.3 mg/kg酵母硒(以硒计)+44 IU/kg VE的日粮。结果表明:妊娠1 d、妊娠60 d、哺乳3 d、哺乳14 d,0.3 mg/kg酵母硒(以硒计)+44 IU/kg VE的日粮获得母猪血清中硒的最高含量。妊娠1 d、妊娠60 d、哺乳3 d、哺乳14 d,各处理母猪血清中抗氧化指标GSH-PX差异不显著。哺乳3 d、哺乳14 d各阶段均反映出0.3 mg/kg酵母硒(以硒计)+44 IU/kg VE的日粮获得乳猪血清中硒的最高含量。不同处理对不同阶段乳猪血清中GSH-PX的含量,哺乳第3 d各处理差异不显著;哺乳14 d添加0.3 mg/kg亚硒酸钠(以硒计)+22 IU/kg VE的处理和0.3 mg/kg酵母硒(以硒计)+44 IU/kg VE处理差异显著(P0.05)。     

酵母对微量元素硒的生物富集及应用

生物富集是指生物体从周围环境中蓄积某种元素或难分解化合物,从而使该物质浓度超过环境中浓度的现象,富集的程度可以用富集系数来表示(王公德,1993)。酵母对许多微量元素如铁、钙、锌、硒、铬及锗等都具较强的富集作用,是一类高效、选择性好、成本低、操作简便的生物富集体。应用酵母富集微量元素有很多优点,除能富集高含量、高吸收率的微量元素外,还可提供相当数量的蛋白质、必需氨基酸、维生素、酶、甘露糖及一些重要的辅助因子等。富集的微量元素有良好的稳定性,便于贮存、运输,并能与饲料中其他成分更好地协同配伍,避免饲料中营养成分…     

利用产朊假丝酵母转化无机硒为有机硒的研究

对富硒酵母进行筛选并对发酵条件进行优化,得到富硒酵母的最适发酵条件:麦芽汁12°Be、培养基加Se量15mg/l、250ml三角瓶装量40ml、初始pH值为6.0、发酵时间40h、温度26℃、转速250r/min,经此培养所得的富硒酵母中的Se含量达到了1451.31μg/g。     

Effects of bacterial organic selenium,selenium yeast and sodium selenite on antioxidant enzymes activity,serum biochemical parameters,and selenium concentration in Lohman brown-classic hens

Veterinary Research Communications - This study compares the effects of sodium selenite, selenium yeast, and enriched bacterial organic selenium protein on antioxidant enzyme activity, serum...     

Brain selenium accumulation in rat pups of selenium supplemented mothers

Selenium is essential for normal mammalian development. Being a component of antioxidant enzyme, glutathione peroxidase, it plays a major role in protecting the cells from free radical damage. The level of glutathione peroxidase was directly related to the amount of selenium present in various tissues and organs. A decrease in selenium leads to various pathological changes in humans as well as in various laboratory animals. The aim of the present study was to understand whether there is an increase in the level of selenium in different brain regions of rat pups whose mothers were supplemented with selenium, either 2 or 4 mg/l of their drinking water throughout the period of their pregnancy. There was a significant increase in the level of selenium in the cerebellum, cortex and hypothalamic and hippocampal tissues of selenium supplemented mothers as compared with those of non-supplemented mothers. The brain stem of these animals did not show any significant difference in the level of selenium. Furthermore, the differences in the level of selenium between the rat pups of 2 mg/l selenium supplemented mothers and 4 mg/l selenium supplemented mothers were not statistically significant. These studies suggest that supplementation of selenium to mothers during the period of their pregnancy can selectively increase the level of this trace element in different brain regions. Further studies are necessary to understand the significance of selective accumulation of selenium in specific brain regions on brain development and function.     

Effect of organic selenium in quail diet on its accumulation in tissues and transfer to the progeny

1. The aim of the present study was to investigate the effects on the eggs and hatchlings (up to 2 weeks post-hatch) of feeding a relatively large amount of so-called organic selenium to breeder quail. 2. Two groups of quail (3 families in each group consisting of 4 females and 1 male) were formed at the beginning of their reproductive period. The quail were fed on a commercial maize-based diet containing 0.096 mg/kg feed-derived selenium (Se), supplemented with 0.2 mg/kg selenite (control group) or 0.5 mg/kg organic selenium in the form of Sel-Plex (Alltech Ltd, USA) for 6 months. Eggs were collected at 6 months of age and Se in the egg yolk, egg white and shell was analysed. Five quail at 1, 7 and 14 d post-hatch were killed to provide samples of liver, brain, breast and leg muscles for Se analysis. After egg collection for analysis and incubation, adult quail were killed and liver, kidney, lung, brain, breast and leg muscles were collected for Se analyses. 3. Inclusion of high doses (0.5 mg/kg) of organic Se in the quail diet was associated with a significant increase in Se concentration in all tissues studied of adult quail as well as in egg yolk, egg albumin and eggshell. 4. Increased Se concentration in the quail egg was associated with increased Se concentration in the liver, breast and leg muscles and brain of newly hatched quail. This difference was shown to be significant for 2 weeks post-hatch. Therefore, it has been suggested that the maternal effect of dietary selenium can be seen beyond the hatching time and more emphasis should be given to this effect in future. 5. It was shown that it is possible to produce Se-enriched quail meat and eggs by adding organic selenium to the diet.     

有机硒在动物体内的营养作用

硒作为动物体内重要的微量元素之一,近几年来已广泛应用于畜禽饲料中。国内外大量研究资料证明,硒在动物体内的代谢过程中以有机硒的形态发生作用,其活性大小与硒结合的组分有关,硒蛋氨酸远比无机硒的利用率高。另外有机硒同无机硒相比,具有吸收率高,生物活性强,毒性小,环境污染小等优点,因而已成为目前硒研究的一个热点。1 有机硒的营养有机硒的最基本作用是参与谷胱甘肽过氧化物酶(GSH-Px)合成,GSH-PX广泛存在于所有动物机体的组织中,起保护细胞膜免受自由基对其膜上的不饱和脂肪酸的过氧化伤害,GSH-PX通过还原型谷胱甘肽(GSH)向氧…     

酵母硒在鸡生产中的应用

本文就酵母硒对鸡生长性能、抗氧化力、免疫力、肉品质、繁殖性能等方面的影响作一综述.     

富硒酵母对肉鸡性能的影响

2000年6月．美国食品与药物管理局（FDA）批准了富硒酵母Sel—PlexTM（SP）作为肉鸡的一种有机硒来源使用。通常,在动物饲料中添加的硒是无机形式的硒酸钠（NaSe）。SP是一种含有多种有机硒化合物的混合物（Kelly等,1995）,主要形式是酵母细胞蛋白成分中的硒代蛋氨酸。SP中的有机硒容易被利用．并可以通过Na^＋-依赖中性氨基酸途径被主动地从肠道中吸收．而亚硒酸盐是被动吸收（Schrauzer,2000）。此外。有报告说,     

The influence of supplements of selenite, selenate and selenium yeast on the selenium status of dairy heifers.

The aim of the study was to define possible differences between selenite, selenate and selenium yeast on various aspects of selenium status in growing cattle. Twenty-four Swedish Red and White dairy heifers were fed no supplementary selenium for 6 months. The basic diet contained 0.026 mg selenium/kg feed dry matter (DM). After the depletion period the animals were divided into 4 groups; group I-III received 2 mg additional selenium daily as sodium selenite, sodium selenate, and a selenium yeast product, respectively. Group IV, the control group, received no additional selenium. The total dietary selenium content for groups I-III during the supplementation period was 0.25 mg/kg DM. After the depletion period the mean concentration of selenium in blood (640 nmol/l) and plasma (299 nmol/l) and the activity of GSH-Px in erythrocytes (610 mukat/l) were marginal, but after 3 months of supplementation they were adequate in all 3 groups. The concentration of selenium in blood and plasma was significantly higher in group III than in groups I and II, but there was no significant difference between groups I and II. The activity of GSH-Px in erythrocytes did not differ between any of the supplemented groups. The animals in the control group had significantly lower concentrations of selenium in blood and plasma and lower activities of GSH-Px in erythrocytes than those in the supplemented groups. The activity of GSH-Px in platelets was also increased by the increased selenium intake. There was no difference in the concentration of triiodothyronine (T3) between any of the groups, but the concentration of thyroxine (T4) was significantly higher in the unsupplemented control group.     

Milk selenium content and speciation in response to supranutritional selenium yeast supplementation in cows

The effects of selenium (Se) yeast supplementation on performance, blood biochemical and antioxidant parameters, and milk Se content and speciation were evaluated. Thirty-six mid-lactation Holstein dairy cows were randomly assigned to 1 of 3 treatments: 1) control (basal diet containing Se at 0.11 mg/kg DM), 2) basal diet + 0.5 mg supplemental Se/kg DM (SY-0.5), and 3) basal diet + 5 mg supplemental Se/kg DM (SY-5). Selenium was supplemented as Se yeast. The trial consisted of a 1-week pretrial period and an 8-week experimental period. Milk somatic cell score decreased with SY-5 supplementation (P < 0.05), but other performance parameters were not affected (P > 0.05). The serum Se concentration increased with the increasing levels of Se yeast supplementation (P < 0.05), however, blood biochemical parameters showed few treatment effects. The antioxidant capacity of dairy cows was improved with Se yeast supplementation reflected in increased serum glutathione peroxidase activity (P < 0.05) and total antioxidant capacity (P = 0.08), and decreased malondialdehyde concentration (P < 0.05). Milk total Se concentration increased with Se dose (P < 0.05). Also, the selenomethionine concentration increased with Se dose from 13.0 ± 0.7 μg/kg in control to 33.1 ± 2.1 μg/kg in SY-0.5 and 530.4 ± 17.5 μg/kg in SY-5 cows (P < 0.05). Similarly, selenocystine concentration increased from 15.6 ± 0.9 μg/kg in control and 18.9 ± 1.1 μg/kg in SY-0.5 to 22.2 ± 1.5 μg/kg in SY-5 cows (P < 0.05). In conclusion, Se yeast is a good organic Se source to produce Se-enriched cow milk with increased Se species including selenomethionine and selenocystine. The results can provide useful information on milk Se species when a high dose Se yeast was supplemented in the cow diet.