碳酸氢铵为氮源对螺旋藻培养的影响

以碳酸氢铵作为氮源,研究在分批培养及流加培养条件下其对螺旋藻生长的影响。结果表明：当培养液中碳酸氢铵浓度小于5mmol/L时,螺旋藻生长正常;碳酸氢铵浓度超过5mmol/L时,螺旋藻生长受到抑制,解体死亡。采用生物量反馈补料的流加策略可以使培养液中螺旋藻生物量达到3.08g/L,产率达到0.26g/(L ·d),藻体中蛋白质及叶绿素含量分别达到65.06%和13.37mg/g,结果证实了碳酸氢铵为氮源高密度培养螺旋藻的可行性。     

极大螺旋藻的硒富集化培养研究

为得到大量含有机硒的极大螺旋藻(Spirulina maxima),以生物量和藻体内硒富集量作为指标,研究不同硒添加量和硒添加方式对极大螺旋藻生长及富硒效果的影响。结果表明,分8d等量(100μL)多次添加100μg/mL Na2SeO3溶液,是最佳添加量和添加方式,可得到生物量为0.903g/L,单位干藻粉有机硒含量为1413.168μg/g的富硒极大螺旋藻。     

极大螺旋藻培养及生物富硒条件的优化

为获得高富硒量的极大螺旋藻,在硒添加方式为8d等量多次添加800μg/mL Se(Ⅳ)的前提下,通过单因子试验研究了初始pH值、光照强度、NaHCO3浓度和NaNO3浓度对富硒极大螺旋藻生物量和硒富集效果的影响.在光照20001x∶50001x= 12h∶ 12h条件下,通过L9 (34)正交试验确定了NaHCO3浓度12.8g/L、NaNO3浓度2.5g/L、pH值9.8为极大螺旋藻生物富硒的最佳条件,得到了生物量为2.517g/L,总硒含量为2.843mg/g(干重)的富硒极大螺旋藻.     

利用膜光生物反应器培养和预采收钝顶螺旋藻的条件

为降低钝顶螺旋藻培养和采收成本,利用膜光生物反应器(MPBR)进行钝顶螺旋藻培养和预采收的条件研究实验。实验结果表明:当生物量达到1.8 g/L时可进行微藻采收;初始藻液质量浓度为1.828 g/L时,MPBR中最大体积浓缩系数为2,最佳稀释率为0.08 d-1,藻产品质量浓度可达3.319 g/L;获得1 g微藻生物量,MPBR中可节约水、氮、磷的量分别为0.301 L、0.248 g、0.053 g。与传统光生物反应器(PBR)相比,MPBR能够降低微藻培养和采收的成本。     

生产纯净水废水培养螺旋藻技术

以钝顶螺旋藻(Spirulina platensis)869藻株为实验材料,在不同营养条件下,用纯净水生产废水培养螺旋藻,同时和AB培养基作对照比较。实验结果显示:在每升纯净水生产废水中添加0.5g K2HPO4,8 g NaHCO3、VB12浓度为0.15μg/L,作为改良废水(1),在改良废水(1)的基础上,再按照AB培养基配方添加As液和PIV液,作为改良废水废水(2),在光强强度4 000 lx、温度24.8℃,光暗周期为12 h∶12 h的条件下培养7 d,钝顶螺旋藻液的吸光度值分别能够达到1.713和1.886,此时对应的生物量是1.601 g(DW)/L和1.766 g(DW)/L。同样条件下用AB培养基进行培养,藻液的吸光度为1.802,生物量是1.688 g(DW)/L,显示出用废水培养螺旋藻的可行性。     

螺旋藻混合营养培养中碳源分析

对螺旋藻混合营养培养过程中无机碳HCO3-和有机碳源葡萄糖进行详细的检测及分析,结果表明:在培养3d时各组所添加的葡萄糖基本用完,培养9d时,葡萄糖浓度为3.0g/L组培养液HCO3-含量最低.同时优选了螺旋藻混合营养培养的NaHCO3添加量,研究发现NaHCO3含量对螺旋藻混合营养细胞积累有很大的影响,NaHCO3的浓度在8.4g/L～16.8g/L时基本对螺旋藻生物量的积累没有太大的影响.     

功能性富锌螺旋藻加工技术的研究

比较了活体螺旋藻、死体螺旋藻和螺旋藻粉吸附Zn2+能力大小以及不同pH值、Zn2+浓度和藻浓度对螺旋藻粉吸附Zn2+的影响。结果表明:螺旋藻粉吸附Zn2+能力大于死体螺旋藻和活体螺旋藻,在pH值为6,螺旋藻粉浓度为1g/L,锌浓度为0.06g/L时,可达到最大吸附率50%,为提高螺旋藻的营养价值和商业价值提供了理论依据。     

光强和CO2体积分数对不同生长时期的钝顶螺旋藻生长和固碳的交互影响

为了提高钝顶螺旋藻生长过程中的比生长速率和固碳速率,对钝顶螺旋藻延迟期、对数期前期、对数期后期和稳定期,光强和CO2体积分数两个主要环境因子进行优选。实验结果表明:钝顶螺旋藻在1 L三角瓶中培养时,在温度30℃,光周期16/8下,延迟期适宜的光强3 000Lux,无需通入CO2;对数期前期适宜的光强为4 000 Lux,需补通15%CO2;对数期末适宜的光强为5 000 Lux,需补通15%CO2;稳定期适宜的光强低于3 000 Lux,无需补加CO2。分四个时期调控培养条件进行钝顶螺旋藻的连续培养,最大生物量和固碳速率均高于对照组,达到4.126 g/L和58.231 mg/(L·h)。     

螺旋藻混合营养培养基配方的优化研究

采用单因素试验和L9(34)正交试验研究螺旋藻混合营养培养过程中碳源NaHCO3、氮源NaNO3、磷源K2HPO4的最佳配比。结果表明:当葡萄糖浓度为3 g/L时,NaHCO3 8.4 g/L、NaNO32.0 g/L、K2HPO4 0.1 g/L即可满足螺旋藻碳、氮、磷营养的需求,干质量达到1.60 g/L。     

分次加硒法培养高富硒量螺旋藻及其对藻体光合色素和蛋白质含量影响的研究

在螺旋藻生长的不同阶段分次添加无机硒(Na2SeO3)进行富硒处理。设置11个实验组,分别从第1天至第10天分次加硒,观察不同硒处理组中螺旋藻对无机硒的富集转化及其光合色素、蛋白质的变化情况。结果表明,在螺旋藻生长的第7、8、9三天分次加硒(实验组7),可获得硒产率1743.06μg/L、有机硒比率为86.85%的高富硒量螺旋藻,与对照相比,其硒含量增加150倍,生物量也明显提高(1.34g/L,对照组为1.18g/L);该实验组藻体中的硒主要分布在水溶性蛋白质中,占总硒含量的60.51%,占有机硒含量的69.67%;螺旋藻主要营养物质藻蓝蛋白(PC)、别藻蓝蛋白(APC)、类叶黄素、β-胡萝卜素含量也有不同程度的增加,表明此富硒方法是螺旋藻高值化处理的有效途径。     

抗氧化剂对螺旋藻流加培养的影响

研究了抗氧化剂Na2S2O3对螺旋藻流加培养的影响,结果表明,当Na2S2O3浓度为0.2 g/L时干质量达到最大值11.14 g/L,是对照的1.75倍,抗氧化效果明显.在此浓度下叶绿素含量及藻胆蛋白含量均达到最大值,并且藻液无污染.     

生长因子对螺旋藻混合营养生长及藻胆蛋白含量影响的研究

本文考察了维生素B12(VB12)、精氨酸(Arg)和萘乙酸(NAA)三个生长因子对螺旋藻混合营养培养的影响,并对藻体干重(DW)及藻胆蛋白(PCP)的含量进行检测。实验结果表明:VB12对螺旋藻生长以及藻胆蛋白的积累均有较大影响,NAA对螺旋藻生长影响较大,而Arg对螺旋藻中藻胆蛋白含量影响较大;在单因素实验的基础上,利用响应面法(RSM)确定三个生长因子的最佳水平:VB12、Arg和NAA水平配比为0.08、45、0.3mg/L,此时藻体干重与藻胆蛋白含量分别增加了20.2%和31.9%;以VB12、Arg和NAA为自变量,建立了藻体干重和藻胆蛋白为响应值的二次多项式数学模型。     

Noncompetitive inhibition by L-cysteine and activation by L-glutamate of the iron-oxidizing activity of a mixotrophic iron-oxidizing bacterium strain OKM-9

A mesophilic, mixotrophic iron-oxidizing bacterium strain OKM-9 uses ferrous iron as a sole source of energy and L-glutamate as a sole source of cellular carbon. Uptake of L-glutamate into OKM-9 cells is absolutely dependent on ferrous iron oxidation. Thus, the Fe(2+)-dependent L-glutamate uptake system of strain OKM-9 is crucial for the bacterium to grow mixotrophically in iron medium with L-glutamate. The relationship between iron oxidation and L-glutamate transport activities was studied. Iron oxidase containing cytochrome a was purified 9-fold from the plasma membrane of OKM-9. A purified iron oxidase showed one rust-colored band following disc gel electrophoresis after incubation with Fe(2+). The Fe(2+)-dependent L-glutamate transport system was also purified 14.5-fold from the plasma membrane using the same purification steps as for iron oxidase. Fe(2+)-dependent L-glutamate and L-cysteine uptake activities of OKM-9 were 0.36 and 0.24 nmol/mg/min, respectively, when a concentration of 18 mM of these amino acids was used as a substrate. Both uptake activities were completely inhibited by potassium cyanide (KCN), suggesting that cytochrome a in the iron oxidase is involved in the transport process. The iron-oxidizing activity of strain OKM-9 was activated 1.7-fold by 80 mM L-glutamate. In contrast, the activity was noncompetitively inhibited by L-cysteine. The Michaelis constant of iron oxidase for Fe(2+) was 12.6 mM and the inhibition constant for L-cysteine was 41.6 mM. A marked inhibition of iron oxidase by 50 mM L-cysteine was completely reversed by the addition of 60 mM L-glutamate. The results suggest the possibility that iron oxidase has a binding site for L-cysteine and the cysteine first bound to the iron oxidase was replaced by the added L-glutamate.     

Production and rapid extraction of lutein and the other lipid-soluble pigments from Chlorella protothecoides grown under heterotrophic and mixotrophic conditions

Chlorella protothecoideswas successfully cultivated under mixotrophic and heterotrophic conditions. The maximum biomass concentrations of the alga grown at an initial glucose concentration of 40 g/l in the light and in the dark were 22.4 g/l and 17.2 g/l dry cells, respectively. A mechanical method using a new model of dispersing instrument, Ulta-Turrax T25, was developed for the extraction of the pigments from C. protothecoidescells. Lutein and the other lipid-soluble pigments were separated well by an HPLC system. The contents of lutein, α-carotene, β-carotene, chlorophyll a and chlorophyll b extracted by the mechanical method from the heterotrophic and mixotrophic C. protothecoidescells were 4.43, 0.32, 0.94, 43.76, 9.14 and 6.48, 0.55, 0.66, 56.75, 9.78 mg/g dry cells, respectively. The recoveries of the five pigments through the mechanical extraction were 97.5–99.6%. In contrast, no chlorophylls a and b were obtained through the alkali extraction.     

不同碳氮组合对三角褐指藻兼养生长及脂质积累的影响

为了探讨兼养培养中不同碳氮组合对三角褐指藻(P.tricornutum)生长及脂质积累的影响,以葡萄糖为碳源,氯化铵为氮源,以不同的碳氮组合兼养培养P.tricornutum,用干重法测定P.tricornutum的生物量,三氯甲烷-甲醇法提取脂质,并采用GC分析脂肪酸组成。结果表明,兼养生长中P.tricornutum基于氯化铵消耗的细胞得率系数随着葡萄糖质量浓度的增加而降低,降低了对氮源的需求;在碳氮组合为葡萄糖质量浓度0.5 g/L,氯化铵浓度1.0 mmol/L的条件下,P.tricornutum生物量达最高,为1.25 g/L,脂质含量可达44.6%,不同碳氮组合对P.tricornutum脂质多不饱和脂肪酸(PUFA)和二十碳五烯酸(EPA)含量的影响不显著。     

盘扣文化

盘扣是中国传统的文化元素,其种类繁多,样式各异,寓意丰富,是劳动人民智慧与艺术的结晶。盘扣是由"结"发展而来的,随着时代的变迁,其功能性与装饰性不仅在服装上得到完美呈现,还不断出现在其他产品上,其独特的设计带有浓厚的时代感、强烈的视觉冲击力及艺术美感。将传统的民族文化元素与现代时尚进行结合,注定盘扣的未来不平凡。     

Influence of yeast culture on ruminal microbial metabolism in continuous culture

A continuous culture study was conducted to evaluate the effect of two different yeast cultures on ruminal microbial metabolism. The treatments were a) control lactation ration, b) yeast culture 1 (YC1, Diamond-V XP) and c) yeast culture 2 (YC2, A-Max), both fed at an equivalent of 57 g/head per day. The results showed that both yeast culture products increased dry matter (DM) digestion, propionic acid production, and protein digestion compared with the control. Yeast culture 1 demonstrated an increase in molar percentage of propionic acid, a reduction in acetic acid, and a lower mean nadir (daily low) pH compared with YC2. Ruminal cultures treated with YC digested more protein and contributed less bypass N than control. Supplementing YC2 resulted in a tendency for higher microbial N/kg DM digestion than YC1. Yeast culture 1 resulted in production of rumen microbes containing less protein and more ash than YC2. These results support previous research findings that yeast culture does influence microbial metabolism, and specific yeast cultures may have different modes of action.     

'Working' culture: exploring notions of workplace culture and learning at work

This article is based on research into the practical problem of masculinity and learning and practising safety in the mining industry. The research began with a post-structural analysis of gendered subjectivity in miners' yarns but argues that a concept of 'culture' is needed to elucidate a middle-level relationship between individual workers and the organisation. Concepts of 'culture', however, are problematic in this context because they have been used uncritically in organisational literature. The author explores the enactment of a concept of 'culture' through an ethnographic study of mine workers. It was found that workplace cultures are characterised by violence and aggression, risk taking, and competitiveness, which impact on learning and practising safety. In emergent understandings of culture in this study the author suggests that 'culture' can be reconceptualised in order to involve workers in their own cultural analysis and to articulate the relationship between the complex, collective, and contested nature of contemporary workplaces and the learning that takes place there. Such a cultural analysis enables the possibility of identifying sites of change and 'culture' as a concept that can be mobilised as a technology for workers to intervene in their own workplace practices.