硒对蜜环菌的作用规律及其在多糖中的积累

采用不同硒浓度对蜜环菌进行了补硒培养,研究了硒对蜜环菌生长、蜜环菌多糖产率的影响以及蜜环菌对硒的积累。结果表明:浓度为10mg/L以下的硒能够促进蜜环菌的生长,超过该浓度之后,硒对蜜环菌的生长产生阻碍;在所设计的浓度范围内,硒能够促进蜜环菌胞内外多糖的合成和分泌。蜜环菌胞内外多糖中硒质量分数都随着硒处理浓度的增加而增加,但硒积累量变化趋势不尽相同。胞内多糖的硒积累量在硒处理浓度为10mg/L时后趋于稳定;胞外多糖硒积累量在硒处理浓度超过5mg/L后仍有增长趋势。     

硒对蛹虫草菌丝代谢和总抗氧化能力的影响

采用在培养基中添加亚硒酸钠的方法来研究硒对蛹虫草菌丝代谢和总抗氧化能力的影响.结果表明:培养基加硒浓度为1mg/L范围内,对蛹虫草菌丝生长有促进作用,加硒浓度为5mg/L～20mg/L时,对蛹虫草菌丝胞外多糖的分泌有促进作用,当培养基加硒浓度为20mg/L时胞外多糖产量最高:培养基加硒浓度为0mg,L～30mg/L,时,对蛹虫草菌丝提取物总抗氧化能力均有显著的增强作用,当加硒浓度为15mg/L时,蛹虫草菌丝提取物总抗氧化能力达到最大.     

富硒香菇多糖发酵工艺的优化及其抗氧化活性

本试验利用香菇作为载体,Na₂SeO₃为添加的硒源,优化富硒香菇多糖的发酵条件并研究其抗氧化活性。采用单因素试验考察了培养基pH、硒灭菌方式、硒添加时间、硒添加量和发酵时间对富硒香菇多糖的影响,并通过 Box-Benhnken实验设计和响应面分析法确定最优发酵条件。在优化条件下得到富硒香菇多糖,并利用DPPH自由基清除能力研究其抗氧活性。结果表明:当培养基pH调至4.16,发酵至第162 h时,向发酵液中添加7.97 mg/L过滤除菌的Na₂SeO₃溶液,发酵11 d,富硒香菇胞内多糖提取量可达到71.54 mg/100 mL;当培养基pH调至4.01,发酵至第191.5 h时,向培养基中添加6.68 mg/L过滤除菌的Na₂SeO₃溶液,发酵11 d,富硒香菇胞外多糖提取量可达到853.96 mg/100 mL。DPPH自由基清除实验结果表明,抗氧化活性大小依次为富硒香菇胞内多糖 > 香菇胞内多糖 > 富硒香菇胞外多糖 > 香菇胞外多糖。硒的添加不仅促进香菇菌丝的生长及多糖的累积,同时也提高了其抗氧化活性,对DPPH有较好的清除作用。     

姬松茸富硒研究

对食药用真菌姬松茸 (Agaricus blazei HS- 3)的耐硒、富硒能力和生物转化进行了研究。结果表明 :在含硒量为 5～ 1 1 5mg/L的固体培养基上 ,菌丝均能生长。当硒含量为5～ 75mg/L范围内 ,菌丝生长速度较对照明显提高 ,在 85～95mg/L范围内 ,与对照接近。当硒含量达到 1 0 5～ 1 1 5mg/L时 ,菌丝生长受到一定抑制。采用液体深层培养 ,在硒含量为5～ 85mg/L范围内 ,菌丝体中硒含量随培养液中硒浓度增加而增加 ,菌丝体富集硒的范围为 8.5～ 69.0 mg/kg。从硒富集率来看 ,当硒含量为 2 5mg/L时最佳 ,达 7.2 %。此时 ,菌体的氨基酸含量明显高于对照 ,多糖含量也略高于对照。     

姬松茸富硒研究

对食药用真菌姬松茸 （Agaricus blazei HS- 3）的耐硒、富硒能力和生物转化进行了研究。结果表明 :在含硒量为 5～ 1 1 5mg/L的固体培养基上 ,菌丝均能生长。当硒含量为5～ 75mg/L范围内 ,菌丝生长速度较对照明显提高 ,在 85～95mg/L范围内 ,与对照接近。当硒含量达到 1 0 5～ 1 1 5mg/L时 ,菌丝生长受到一定抑制。采用液体深层培养 ,在硒含量为5～ 85mg/L范围内 ,菌丝体中硒含量随培养液中硒浓度增加而增加 ,菌丝体富集硒的范围为 8.5～ 69.0 mg/kg。从硒富集率来看 ,当硒含量为 2 5mg/L时最佳 ,达 7.2 %。此时 ,菌体的氨基酸含量明显高于对照 ,多糖含量也略高于对照。      

硒浓度对小球藻生长、生物富集的影响

研究了硒浓度对小球藻生长的影响,以及硒浓度对小球藻生物富集的影响,并对相关的可能机理进行了讨论.研究发现,高浓度的硒对小球藻生长具有抑制作用,当硒浓度超过1mg/L时会产生抑制作用;当硒浓度增至12mg/L时,发现藻细胞生长几乎停止.小球藻对硒的生物富集随着硒浓度的增加而增加,硒浓度为1mg/L时,藻体的硒含量为9.92μg/g;当硒浓度为8mg/L时,藻体的硒含量达到了83.66μg/g.小球藻富硒培养较适宜的硒添加浓度是4mg/L～8mg/L.     

微量元素与功能性螺旋藻

螺旋藻对微量元素有很强的生物富集作用。研究表明,螺旋藻对Cr、Zn、Se三种微量元素均有明显的富集作用,且它们之间存在吸附竞争;通过富集适量的硒可以促进螺旋藻生长及胞外多糖积累。当培养基中硒(Ⅳ)的浓度为400mg/L以下时,显著促进螺旋藻生物量的增长,但浓度太高对螺旋藻的生长有抑制作用;当硒(Ⅳ)的浓度为300mg/L时,胞外多糖量达到最大值18mg/L,而未添加硒时的分泌量最大为11mg/L。     

外源硒对茎瘤芥硒形态及硒吸收的影响

采用大田实验研究叶面喷施硒(0.0、1.0、2.5 mg/L)对茎瘤芥生长、硒形态、硒吸收和转化的影响。结果表明,叶面喷施1.0 mg/L的硒提高了茎瘤芥的产量,但未达到显著水平(P0.05)。叶面喷硒降低了茎瘤芥硝酸盐含量,在一定程度上增加了茎瘤芥游离氨基酸、VC、还原糖的含量,分别较对照增加了40.41%、13.36%和46.73%。叶面喷施硒后茎瘤芥中全硒和有机硒含量分别较对照增加了46.1%~193.9%和74.0%~271.5%,并且随外源硒质量浓度的升高而显著增加。随硒质量浓度的增加,茎瘤芥有机硒转化率显著提高,1.0、2.5 mg/L硒处理分别较对照增加了19.33%和23.57%。茎瘤芥吸收的硒主要以有机硒的形式存在,茎瘤芥全硒和有机硒含量与外源硒质量浓度呈极显著正相关(P0.01)。     

乳酸菌胞外多糖硒化修饰及其抗氧化活性研究

探讨了乳酸菌胞外多糖硒化修饰的最佳工艺条件,以及硒化胞外多糖的抗氧化活性。通过单因素试验确定反应温度、反应时间、硒化剂添加量的取值范围,再用响应面设计法确定最佳硒化修饰条件。试验结果表明:反应温度、反应时间、硒化剂添加量显著影响乳酸菌胞外多糖硒化的程度,当反应温度50℃、反应时间13.5h、硒化剂添加量0.55mg时硒含量和硒转化率达到最大值。在此条件下,所得硒多糖硒含量169.228μg/g,硒转化率32.37%;硒化后的多糖总抗氧化能力及对羟自由基的清除能力显著增强,而对超氧阴离子自由基的清除能力变化不大。     

虫草与富硒虫草多糖的体外抗氧化活性

采用Fenton法和邻苯三酚自氧化法测定虫草和富硒虫草多糖对.OH、O2-.和H2O2的清除率。结果表明:虫草多糖对O-2.和H2O2的清除能力依次为富硒虫草胞外多糖>富硒虫草胞内多糖>虫草胞外多糖>虫草胞内多糖,而对.OH的清除能力依次为:富硒虫草胞外多糖>虫草胞外多糖>富硒虫草胞内多糖>虫草胞内多糖;当100mg/L多糖溶液添加量分别高于80、40、90μL时,各组多糖对.OH、O2-.和H2O2 3种自由基的抑制率均可高于50%。     

富硒酵母中硒含量的测定

本文报道了一种简便可靠的测定富硒酵母中硒含量的方法。采用双氧水：高氯酸：硫酸＝３：３：１的消化液处理样品,用联苯胺比色法测定样品总硒含量,回收率达９６．９％,变异系数为１．６４。     

Relationship of selenium concentrations in blood of calves to blood selenium of the dam and supplemental selenium

Selenium status of dam, injected Se, and dietary Ca on calf blood Se concentrations were determined in two trials. Blood was collected from heifer calf and dam pairs at parturition. Half of the calves were injected intramuscularly with .0825 mg Se/kg body weight at birth while the other half received no Se injections. The concentration of Se in the blood of the dam had a significant effect on blood Se of calves at wk 0, 1, and 3, whereas injected Se did not significantly affect blood Se concentrations in the calf until wk 10. In a separate trial, whole blood and plasma Se were significantly correlated at birth in calves, but plasma Se was only about one-third the concentration of whole blood. The concentration of dietary Ca in the calf starter did not significantly affect blood Se, but a quadratic relationship was suggested. Plasma Zn in calves was elevated at birth and then declined with age whereas plasma inorganic P increased with age. Early postnatal concentrations of Se in blood of calves are largely a function of the dam; thus, in areas of low Se intakes, Se supplements for the dam are important.     

Soil selenium treatments to ameliorate selenium deficiency in herbage

Sodium selenite, sodium selenate, and sodium selenate in a pill formulation were applied to three soils known to produce Se-deficient herbage ( < 100 μg Se kg^?1 dry matter (DM)). The ability of the salts, applied in spring 1985, to ameliorate Se deficiency was followed over 3 years by taking four harvests each year. Selenate treatment at 10 g Se ha^?1 and selenate prill treatment at 20 g Se ha^?1 produced herbage with Se levels (geometric means) of between 0.57-0.86 and 1.79-1992 mg kg^?1 DM respectively in the first spring harvest after treatment. Selenite was less potent and selenite at 100 g Se ha^?1 produced a response in herbage closely similar to that of selenate at 10 g Se ha^?1. Even at 300 g Se ha^?1 the selenite treatment produced herbage with only 1.00-1.36 mg Se kg^?1 DM at the first harvest. Application of selenate in the prill form at 60 g Se ha^?1 produced herbage potentially toxic to grazing animals with 4.81-4.94 mg Se kg^?1 DM. The addition of fertiliser N to Se-treated plots increased total Se uptake at the first harvest by a factor of 4 and had a small effect on Se concentration. The Se concentration levels in herbage from Se-treated plots declined exponentially (t_1/2 = 21-43 days). On one soil derived from Lower Old Red Sandstone and lava, selenite at 300 g Se ha^?1 gave herbage with Se contents significantly above background (P < 0.05) in all harvests over 3 years.     

土壤施硒对白肋烟含硒量的影响

盆栽试验结果表明,在本试验设定的土壤施硒范围内,白肋烟叶、根、茎的含硒量分别为3.8~210、2.2~57、1.4~42μg/g,呈叶 > 根 > 茎的分布规律,而且均与土壤施硒量呈极显著的正相关;白肋烟叶、茎、根的吸硒量分别为0.208~11.343、0.143~3.682、0.032~1.000 mg/pot,呈现叶 > 茎 > 根的分布规律,亦均与土壤施硒量呈极显著的正相关:叶、茎、根的吸硒量占烟株总吸硒量的比例分别为54.3%~70.8%、20.8%~37.5%、5.5%~9.5%,说明白肋烟的硒积累能力为叶 > 茎 > 根;白肋烟对土壤施硒的回收率为8.9%~18.1%。      

Daily selenium intake in a moderate selenium deficiency area of Suzhou,China

In this study the daily dietary Selenium (Se) intake in Suzhou was investigated to determine whether residents in such a developed region were susceptible to moderate Se deficiency. Concentrations of Se in typically consumed foods in Suzhou were determined. Based on food Se content and the daily per capita consumption, the estimated Se intake in Suzhou was 43.9 ± 3.8 μg day⁻¹. The results revealed that pork and cereals were the major sources of Se daily intake and contributed 24.7% and 22.6% to the daily Se intake, respectively. The Se content in hair of local residents was 389.9 ± 103.6 μg kg⁻¹ for male and 322.9 ± 101.8 μg kg⁻¹ for female. A significant linear correlation between the daily Se intake and the hair Se concentration was established. The hair Se concentration could be used to bioindicate the level of Se intake for longer period.     

Meta-analysis of the effect of oral selenium supplementation on milk selenium concentration in cattle

Soils in many regions of the world have a low Se content. Consequently, forages and crops grown on these soils may provide inadequate dietary Se for humans and grazing animals. Selenium supplementation has been used to enhance Se status and milk Se concentration, but results conflict. Milk Se concentration appears to be a useful indicator of animal and herd Se status, and reflects the responsiveness to supplementation. A systematic review and meta-analysis were carried out to summarize all available scientific evidence for the effect of oral Se supplementation on milk Se concentration in cattle. The literature search was based on electronic and nonelectronic databases. Fixed- and random-effects models of meta-analysis were used, and a meta-regression was carried out to evaluate heterogeneity among studies. Random-effects meta-analysis was performed on 42 studies published between 1977 and 2007. Oral Se supplementation resulted in an average increase in milk Se content of 0.16 (95% confidence interval: 0.117, 0.207) μmol/L, with a significant heterogeneity among studies. Weak publication bias was evident, but it did not change the average effect. The continent where the study was performed, Se source, Se dose, and the interaction between source and dose explained 71% of the between-study variance. On average, American cows supplemented with Se yeast (e.g., 6 mg/h per day) had greater milk Se concentrations (approximately 0.37 μmol/L) 75 d after the beginning of supplementation when compared with those supplemented with inorganic forms of Se. This information provides a basis for tailoring daily animal requirements and for enhancing the Se intake of consumers of dairy products.     

Influence of various selenium sources on selenium concentration in the milk of dairy cows

Selenium (Se) as essential trace element is supplemented in various compounds to rations of food producing animals. In human nutrition the range between Se requirement and upper level is very small (1:3–5). Hence, food of animal origin may contribute to Se supply of humans, but can also offer high amounts of Se and exceed the Se upper level for humans. Therefore the transfer into the milk of inorganic (0.2 and 0.4 mg Se from sodium-selenite) or organic (Se methionine) Se-compounds was tested. Fifteen lactating German Holstein cows were fed diets without supplementation (0.1 mg Se/kg dry matter, DM) or supplemented with inorganic or an organic Se-compound over 3 weeks. Se-supplementation did not significantly influence feed intake, milk yield and composition as well as animal health. Se-concentration of milk increased from 13.3 over 17.6 to 19.7 μg/L in the case of inorganic Se supplementation and from 13.9 over 24.6 to 54.8 μg/L after Se-yeast addition.     

富硒绿茶中锌、硒、铅、铝的溶出研究

目的研究富硒绿茶冲泡过程锌、硒、铅、铝4个元素的溶出,为科学饮茶提供指导。方法通过在实验室模拟茶叶冲泡过程,采用电感耦合等离子体质谱(inductively coupled plasma-mass spectrometry,ICP-MS)测试了不同冲泡时间和不同冲泡次数下茶汤中锌、硒、铅、铝的溶出率。结果锌、硒的溶出在30 min内相对增长较快,并且经3~4次冲泡溶出可溶出部分达80%;铅在5 min内和第1次冲泡溶出可溶出部分达50%以上;铝在整个过程溶出平稳,总溶出率小于10%。结论锌、硒、铅、铝4个元素在不同冲泡时间和不同冲泡次数下溶出性不一致;适度洗茶,可以去除较多铅的可溶性部分,而锌、硒损失较少;长时间浸泡和多次冲泡后,各元素溶出量增加较少。     

Concentrations of selenium in human milk

 Selenium (Se) concentrations in 58 samples of mature human milk from Canarian women were determined by spectrofluorimetry. According to the literature the Se concentrations found fall within the normal limits. The concentration of Se in human milk was compared with that in powdered infant formula and presented significantly lower concentrations in the latter. Babies fed with human milk had an adequate intake of Se. However, babies fed with powdered infant formula consumed only 56% of the requirements recommended by The National Research Council. No changes in Se concentration were observed between lactation stages. Human milk produced in springtime was found to be richer in Se than that produced in the autumn, which could be due to changes in the nutritional habits of the mothers. The mother's age, weight, height and number of previous children were not found to influence the Se levels in the milk. Received: 19 January 1998