氮源类型和水平对3株球状绿藻生长、油脂和花生四烯酸积累的影响

【背景】缺刻叶球藻(Lobosphaera incisa Reisigl)是一种单细胞球状绿藻,是已知花生四烯酸(Arachidonic acid,AA)含量最丰富的植物资源之一。然而目前其分类和命名仍然较为混乱。【目的】明确3株球状绿藻(SAG2468、SAG2043、H4301)的分类地位及在不同氮源(硝酸钠、尿素、碳酸氢铵、碳酸铵、硝酸铵、氯化铵和硫酸铵)和氮浓度(18mmol/L,3mmol/L)条件下油脂和AA积累的特性。【方法】通过分子系统学和形态观察的方法对3株球状绿藻进行分类界定;采用干重法、重量法和气相色谱分析的方法分别对其生物量、油脂含量、脂肪酸组成及AA含量进行测定。【结果】3株球状绿藻均隶属于叶球藻属(Lobosphaera),SAG2468原定名为缺刻缘绿藻(Parietochloris incisa),现修订为缺刻叶球藻(Lobosphaera incisa),与H4301为缺刻叶球藻的不同地理株系。SAG2043原定名为双隔蚁形藻(Myrmecia bisecta),现修订为双隔叶球藻(Lobosphaera bisecta)。3株微藻在高氮(18 mmol/L)和低氮(3 mmol/L)浓度的硝酸钠和尿素培养条件下均可良好生长,铵盐对藻细胞生长普遍有抑制作用,且浓度越高抑制作用越显著。低氮胁迫能显著促进油脂和AA的积累(P0.05),SAG2043在3 mmol/L硝酸钠条件下油脂和AA产率最高,分别为142.15mg/(L·d)和35.51mg/(L·d),明显高于另外2株微藻(P0.05)。此时SAG2043对应获得的生物量为4.9 g/L,油脂含量为43.49%,AA含量高达干重的10.86%,占总脂肪酸含量的31.75%。【结论】SAG2043是一株更具AA开发潜力的微藻。     

光径及氮浓度对缺刻缘绿藻生长、油脂和花生四烯酸积累的影响

以缺刻缘绿藻(Parietochloris incisa)为实验材料, 采用BG-11培养基, 分别在2种氮浓度和3种不同光径(LP)的柱状和平板光生物反应器中进行培养, 并探究其生长、油脂和花生四烯酸(AA)的积累规律。结果显示: 在两种光生物反应器中, 光径越小, 越有利于缺刻缘绿藻的生长。其中, 最大生物量均在17.6 mmol/L氮浓度时获得, 分别为5.09 g/L(2.5 cm-柱状)和2.98 g/L(3.0 cm-平板); 而最高油脂和AA绝对含量则均在1.0 mmol/L氮浓度和最大光径处获得, 分别为39.23%、13.21%(6.0 cm-柱状)和40.74%、11.33%(5.0 cm-平板); 另外, 两种光生物反应器中的最大油脂单位体积产率分别可以达到216.39 mg/(L·d)(17.6 mmol/L; 2.5 cm-柱状)和135.93 mg/(L·d)(1.0 mmol/L; 1.5 cm-平板); 而最高的AA单位体积产率均在1.0 mmol/L低氮条件, 最大光径处达到最大, 分别为21.65 mg/(L·d)(6.0 cm-柱状)和19.42 mg/(L·d)(5.0 cm-平板)。因此, 根据实际生产需要, 在1.0 mmol/L低氮条件下, 选择6.0 cm光径的柱状光生物反应器或5.0 cm光径的平板光生物反应器, 培养缺刻缘绿藻生产AA, 能有效降低生产成本。     

光强和氮源及其浓度对缺刻缘绿藻生长、油脂和花生四烯酸积累的影响

对缺刻缘绿藻（Parietochloris incisa（Reisigl） S.Watanabe）在不同光强和氮源及其浓度条件下的生长状况及油脂和花生四烯酸（AA）的积累规律进行了研究。结果显示,缺刻缘绿藻在3种氮源条件下均能较好地生长。在高氮浓度条件下,增大光强能显著提高缺刻缘绿藻的生物量并促进油脂和AA的积累。缺刻缘绿藻在300 μmol·m^-2·s^-1光强、8.8 mmol·L^-1NaNO₃条件下生物量达到最大（4.17 g·L^-1）。油脂含量在100 μmol·m^-2·s^-1光强、1.0 mmol·L^-1氮浓度下达到最高,分别为41.17%（NaNO₃）、42.04%（NH₄HCO₃）和39.96%（CO（NH₂）₂）。AA绝对含量在300 μmol·m^-2·s^-1光强、2.9 mmol·L^-1 NaNO₃条件下达到最高,占细胞干重的16.44%。油脂和AA产率,在300 μmol·m^-2·s^-1光强、以NaNO₃为氮源的条件下达到最大,分别为134.6 mg·L^-1·d^-1（1.0 mmol·L^-1）和35.85 mg·L^-1·d^-1（2.9 mmol·L^-1）。综合考虑成本等因素,选择NH₄HCO₃（5.9 mmol·L^-1）和CO（NH₂）₂（2.9 mmol·L^-1）为氮源、在300 μmol·m^-2·s^-1高光强下培养缺刻缘绿藻进行AA的生产为最优方案。     

光强及氮浓度对丝状绿藻双星藻生长及生化组成的影响

[背景]环境因子和营养因子对微藻的生长和生化组成都有显著的影响,其中光强和氮浓度是最重要的两个条件。[目的]研究不同光强和初始氮浓度对丝状绿藻-双星藻(Zygnema sp.)生长及生化组成的影响。[方法]采用改良的BBM培养基,设置了两组光强[100μmol/(m^2·s)和300μmol/(m^2·s)]和6种初始氮浓度(3、6、9、12、15和18 mmol/L)在柱状光生物反应器中对双星藻进行培养。[结果]在高光强条件下[300μmol/(m^2·s)],12 mmol/L初始氮浓度最有利于双星藻生物质的积累,其最高生物量可以达到6.60 g/L,而初始低氮浓度(3 mmol/L)则促进了油脂和脂肪酸的积累,油脂最高含量占干重的32.13%,且脂肪酸组成主要包括棕榈酸(C16:0)、油酸(C18:1)、亚油酸(C18:2)和亚麻酸(C18:3),其中油酸含量最高达到总脂肪酸含量的55.01%;在低光强条件下[100μmol/(m^2·s)],初始氮浓度为18 mmol/L时,总蛋白质和总碳水化合物的含量达到最高,分别占干重的16.35%和37.70%,而总脂含量仅占干重10.16%。[结论]光强和初始氮浓度对双星藻生长具有较大影响,通过调节光强和初始氮浓度可有效提高双星藻目标代谢产物的积累。     

塔玛亚历山大藻对氮和磷的吸收及其生长特性

参照塔玛亚历山大藻(Alexandrium tamarense)赤潮爆发时的物理条件,以f／2加富的人工海水为培养基,设定了不同的氮、磷水平,研究了在室内批量培养条件下,塔玛亚历山大藻对无机氮、磷的吸收和无机氮、磷对塔玛亚历山大藻细胞生长的影响．结果表明,3种氮浓度条件下,塔玛亚历山大藻的比生长速率几乎没有差异,但低氮(0．0882mmol·L-1)条件下,藻细胞的生物量最低;中氮(0．882mmol·L-1)条件下,藻细胞具有最大的生物量,分别比高氮(2．646mmol·L-1)和低氮下增加44．7％和53．6％．随着培养基中磷浓度的升高,藻细胞生物量也升高,在高磷(0．108mmol·L-1)条件下达到最大值17200cell·ml-1,但在中磷(0．036mmol.L-1)条件下藻细胞具有最大的比生长速率．藻细胞对氮、磷的吸收速率与生长状态有密切关系,氮、磷限制条件下生长的藻细胞对氮、磷有快速的吸收．研究显示,低的N／P比有利于塔玛亚历山大藻的生长分裂,对数生长后期适当补氮则有利于其生物量的积累．     

营养盐初始组合浓度对类波氏真眼点藻生长和油脂积累的影响

为了研究培养基中主要营养元素氮、磷、硫初始组合浓度对类波氏真眼点藻(Eustigmatos cf.polyphem D.J.Hibberd)生长、油脂积累和脂肪酸组成的影响,分别以NaNO_3、K_2HPO_4、MgSO_4为氮、磷、硫源,设置不同的营养盐初始组合浓度对其进行培养,采用干重法、重量法、气相色谱分析法、元素分析仪等依次对生物量、总脂、脂肪酸组成和细胞内元素含量进行测定。结果显示,氮、磷、硫三者的初始组合浓度变化对类波氏真眼点藻的生长和油脂积累具有明显的影响,9 mmol/L NaNO_3、0.92 mmol/L K_2HPO_4、0.3 mmol/L MgSO_4营养条件下其生物量达到最大值,为9.19 g/L;低氮、低磷胁迫或二者共同胁迫均促进其油脂积累,但低硫胁迫对油脂的积累影响不大,最大油脂含量出现在3 mmol/L NaNO_3、0.029 mmol/L K_2HPO_4、0.3 mmol/L MgSO_4条件下,为68.7%(DW)。此外,类波氏真眼点藻富含棕榈油酸,占总脂肪酸含量的最大值达60.88%。选择合理的氮、磷、硫初始组合浓度能够有效促进其生长或油脂及棕榈油酸的积累。     

氮胁迫对埃氏小球藻生长及油脂积累的影响

以生长快、可除污的埃氏小球藻株系SXND-25为试材,研究不同氮浓度培养条件对其生物量和油脂产量的影响,以期建立优化培养体系利用该株小球藻生产优质生物燃油。以硝酸钠为氮源、BG11培养基中的氮浓度为基准(1.5 g/L),设置氮浓度梯度对小球藻进行培养。通过光密度测定、尼罗红染色、转酯化法抽提油脂和GC分析,对小球藻生物量、油脂含量及脂肪酸组分进行分析。结果显示,培养8 d时,在氮浓度为1.5 g/L时,生物量达到最大,干重为3.4 g/L,而油脂含量仅为28.24%,油脂产量为0.96 g/L;在氮浓度为0 g/L时生物量最小,干重为0.49 g/L,而油脂含量最高,为44.57%,油脂产量为0.22 g/L;在氮浓度为0.75 g/L时,干重为3.2 g/L,油脂含量为40.36%,油脂产量最高为1.3 g/L,是标准氮浓度下油脂产量的1.4倍。0.75 g/L氮浓度下连续培养8 d,藻油脂肪酸组成更适于制取优质生物柴油。综合生物量、油脂含量及脂肪酸组成等指标,确定0.75 g/L氮浓度为该埃氏小球藻株系规模化培养以生产优质生物燃油的优化参数。     

囊状黄丝藻在不同初始氮浓度条件下特殊的油脂积累规律

对不同初始氮浓度条件下囊状黄丝藻(Tribonema utriculosum SAG22.94)的生长状况、油脂含量和脂肪酸组成与含量进行研究。结果显示,囊状黄丝藻在氮浓度为3.0 mmol/L时,获得生物质浓度最高,为6.39 g/L;氮浓度为18.0 mmol/L时获得总脂和总脂肪酸含量最高,分别为细胞干重的44.62%和42.21%;上述3个指标单位体积的产率均在氮浓度3.0 mmol/L时达到最高值,分别为0.538、0.209和0.206 g·L~(-1)·d~(-1)。在4种初始氮浓度条件下,囊状黄丝藻油脂和脂肪酸含量可随着氮浓度增加而增加。脂肪酸含量分析结果显示,该藻的主要脂肪酸为豆蔻酸(C14∶0)、棕榈酸(C16∶0)、棕榈油酸(C16∶1ω7)、花生四烯酸(C20∶4ω6)和二十碳五烯酸(C20∶5ω3,EPA)。其中棕榈油酸含量最高,占总脂肪酸含量的36.53%~50.08%。研究结果表明囊状黄丝藻在不同初始氮浓度条件下具有特殊的油脂积累规律,是一株具有重要应用价值的产油丝状微藻。     

Different responses of biomass allocation and leaf traits of Dodonaea viscosa to concentrations of nitrogen and phosphorus

调整叶性状和生物量分配格局是植物适应环境变化的主要途径, 研究车桑子(Dodonaea viscosa)幼苗生物量分配与叶性状对氮磷浓度的响应对认识车桑子在氮磷浓度变化下的适应策略具有重要意义。该研究通过砂培法, 测定不同氮浓度(3、5、15、30 mmol·L^-1)与不同磷浓度(0.25、0.5、1、2 mmol·L^-1)下车桑子幼苗的生长、生物量分配、叶性状的响应特征及其相互关系。结果表明: 高浓度氮(30 mmol·L^-1)促进了车桑子幼苗生长、叶片氮含量和生物量积累, 其余氮添加条件(3、5、15 mmol·L^-1)下车桑子幼苗各性状无显著差异, 但相比高氮水平, 其生物量积累和叶片氮含量显著降低, 根冠比和氮利用效率显著增加。随着磷添加浓度的增加, 车桑子幼苗生物量显著增加, 低磷条件(0.25、0.5 mmol·L^-1)限制了车桑子幼苗生长和生物量积累, 其根冠比和磷利用效率均没有发生显著变化, 但比叶面积和叶/茎生物量比例显著增加, 叶干物质含量显著降低。氮处理下, 叶片氮含量与根冠比显著负相关; 磷处理下, 叶片氮含量与比叶面积显著正相关。同时, 氮处理下, 车桑子幼苗株高、基径、总生物量等生长性状均与根冠比显著负相关, 与叶片氮含量显著正相关, 表明根冠比和叶片氮含量的调整在车桑子适应氮限制中发挥重要作用; 而磷处理下, 株高、基径、总生物量与比叶面积显著负相关, 与叶干物质含量显著正相关, 表明叶片结构性状的调整在车桑子适应低磷环境中具有重要意义。该研究表明, 车桑子幼苗生物量分配和叶性状及性状间的权衡策略对氮、磷的响应具有明显差异性, 在今后的研究中, 应关注氮和磷对植物性状影响的差异性。     

车桑子幼苗生物量分配与叶性状对氮磷浓度的响应差异

调整叶性状和生物量分配格局是植物适应环境变化的主要途径, 研究车桑子(Dodonaea viscosa)幼苗生物量分配与叶性状对氮磷浓度的响应对认识车桑子在氮磷浓度变化下的适应策略具有重要意义。该研究通过砂培法, 测定不同氮浓度(3、5、15、30 mmol·L^-1)与不同磷浓度(0.25、0.5、1、2 mmol·L^-1)下车桑子幼苗的生长、生物量分配、叶性状的响应特征及其相互关系。结果表明: 高浓度氮(30 mmol·L^-1)促进了车桑子幼苗生长、叶片氮含量和生物量积累, 其余氮添加条件(3、5、15 mmol·L^-1)下车桑子幼苗各性状无显著差异, 但相比高氮水平, 其生物量积累和叶片氮含量显著降低, 根冠比和氮利用效率显著增加。随着磷添加浓度的增加, 车桑子幼苗生物量显著增加, 低磷条件(0.25、0.5 mmol·L^-1)限制了车桑子幼苗生长和生物量积累, 其根冠比和磷利用效率均没有发生显著变化, 但比叶面积和叶/茎生物量比例显著增加, 叶干物质含量显著降低。氮处理下, 叶片氮含量与根冠比显著负相关; 磷处理下, 叶片氮含量与比叶面积显著正相关。同时, 氮处理下, 车桑子幼苗株高、基径、总生物量等生长性状均与根冠比显著负相关, 与叶片氮含量显著正相关, 表明根冠比和叶片氮含量的调整在车桑子适应氮限制中发挥重要作用; 而磷处理下, 株高、基径、总生物量与比叶面积显著负相关, 与叶干物质含量显著正相关, 表明叶片结构性状的调整在车桑子适应低磷环境中具有重要意义。该研究表明, 车桑子幼苗生物量分配和叶性状及性状间的权衡策略对氮、磷的响应具有明显差异性, 在今后的研究中, 应关注氮和磷对植物性状影响的差异性。     

Relationships of Starch Concentration with Specific Leaf Weight and Mineral Concentrations in Potato Leaves Under Varied CO2 and Temperature

Foliar concentrations of starch and major nutrients N, P, K, Ca, and Mg along with specific leaf weight (SLW) were determined in the potato (Solaruan tuberosum L. ) cvs "Denali", "Norland” and "Russet Burbank" grown for 35 days under the CO2 concentrations of 500, 1 000, 1 500 and 2 000 μmol' mol-l at both 16 and 20 ℃ air temperature. The starch concentration, pooled from the three cuhivars, increased with increasing CO2 concentration at both 16 and 20 ℃, and was consistently higher at 16 ℃ than at 20 ℃. The SLW (g·m-2) was positively related to the foliar starch concentration on the basis of leaf area or dry weight. The concentrations of N, P, Ca, and Mg in leaves were negatively related to starch concentration under 14% starch on a dry weight basis. Above 14%, there was no significant relationship between nutrient and starch concentrations. The similar patterns were seen when the SLW and nutrient concentrations were expressed on a starch-free basis. In contrast, the leaf concentration of K was not closely related to the starch concentration. The results indicated that the changes in SLW and concentrations of N, P, Ca, and Mg in potato leaves only partially resulted from the changed starch concentration.     

A method for concentrating dilute solutions of macromolecules

A simple, inexpensive acrylate polymer which has a capacity to absorb 170 ml of water per g has been developed. It can be used to concentrate dilute solutions of macromolecules such as proteins, nucleic acids, and carbohydrates. The polymer absorbs only low-molecular-weight substances such as glucose, sucrose, and inorganic salts. It can replace the various conventional concentration methods. No special device or electricity is needed for the concentration. The inexpensive polymer, molded in the form of rods, can be very conveniently used as “disposable concentration sticks.”     

Smoking does not influence cadmium concentrations in blood and urine in relatively high levels of environmental cadmium areas in Japan

We examined how the influence of smoking on blood and urinary cadmium (Cd) concentrations was modified by the level of environmental Cd. We measured blood and urinary Cd concentrations of 1134 men over 50 yr of age in three areas in Japan that were exposed to different levels of environmental Cd. Analysis of variance was used to compare Cd concentrations in blood and urine of smokers with those of nonsmokers living in the three areas. Correlation coefficients between the number of cigarets smoked per day or smoking indices (the number of cigarets smoked per day multiplied by the number of years smoked) and blood and urinary Cd concentrations were calculated. No significant difference in Cd concentrations between smokers and nonsmokers was observed in areas where the average Cd concentration in blood was over approx 2.4 ng/g, 2.0 μg/L in urine, and 2.3 μg/g creatinine in urine, respectively. Therefore, it was suggested that an influence of smoking on blood and urinary Cd concentrations was not observed in areas exposed to relatively high levels of environmental Cd.     

Antifungal activity of essential oils and their combinations in in vitro and in vivo conditions

Natural additives are in demand for the control of microbial growth in foods. Several natural compounds including essential oils (EOs) are being explored for food uses. In the present investigation, the antifungal activity of cinnamaldehyde, eugenol, peppermint and clove EOs and their combinations was evaluated against 12 species of Aspergillus, Fusarium, Penicillium and Rhizopus in in vitro and tomato fruit system (in-vivo). The EOs were able to inhibit complete growth of tested fungi at or below 0.6% level and 80?μL of EOs (except peppermint oil) in in vitro condition and tomato system, respectively. The fractional inhibitory studies showed either additive or indifferent effect by combining eugenol and peppermint, and indifferent or antagonist effect by combining the cinnamaldehyde and clove in both in vitro and in vivo studies. The findings may be useful for application of these EOs in foods, but their effects on organoleptic quality of foods need to be investigated.     

过氧化钙的净水增氧效果评估

过氧化钙作为一种新型净水剂,其净水和增氧效果尚未确定.通过研究过氧化钙对海水的化学需氧量、pH值以及氨氮的影响,从水化学的角度确定过氧化钙用量与主要水质指标变化的关系;通过过氧化钙对卤虫孵化和细菌计数,来确定过氧化钙用于净化水质的安全浓度和有效浓度,从而指导水产养殖实践中的实际用量.实验结果表明,施加0.1%的过氧化钙既可以显著降低海水中的化学需氧量和氨氮含量,提高溶解氧和pH值,同时可有效抑制细菌的繁殖,而且对卤虫孵化也是安全的.     

亚热带米老排和杉木细根分解过程中养分与微生物群落组成的变化

对福建南平峡阳林场19年生米老排和杉木人工林的细根进行为期12个月的分解试验,研究不同树种分解过程中养分和微生物群落组成的动态变化,为理解亚热带不同人工林树种地下养分循环过程提供科学依据.结果表明: 米老排细根养分磷(P)、钾(K)初始含量显著高于杉木.分解过程中,两个树种细根P、K含量均显著降低,而细根氮(N)含量显著增加,且杉木细根N含量变化滞后于米老排.在分解过程中,杉木细根镁(Mg)含量无显著变化;米老排细根Mg含量变化显著,且在分解8个月时显著小于杉木.在分解过程中,真菌与细菌比值均显著表现为先升高后降低,且分解12个月时米老排细根真菌/细菌显著高于杉木.冗余分析表明,N(解释37.2%)、K(解释14.5%)含量和C/N(解释14.8%)是影响杉木细根分解过程中微生物群落组成变化的主要养分因子,而Mg(解释35.9%)和K(解释17.6%)含量则是米老排细根分解时影响微生物群落组成的主要养分因子.研究表明,在不同树种中,除了N之外,Mg等其他养分元素也可能是影响根系分解的重要因子.     

Iodine status in Danish pregnant and breastfeeding women including studies of some challenges in urinary iodine status evaluation

Denmark was previously iodine deficient with regional differences. Moderate iodine deficiency appeared in West Denmark and mild iodine deficiency in East Denmark and also Danish pregnant and breastfeeding women suffered from iodine deficiency. The Danish mandatory iodine fortification of salt was introduced in the year 2000 and has increased iodine intake in the Danish population. However, median urinary iodine concentration in the general population and in pregnant and breastfeeding women is still below the level recommended, corresponding to mild iodine deficiency. Certain characteristics may challenge the evaluation of urinary iodine status in pregnancy and during breastfeeding. This review also addresses methodological challenges related to spot urine sampling conditions and the use of iodine supplement and discusses the use of non-pregnant population groups as a proxy for iodine intake in pregnant women.     

松嫩平原草甸三种植物叶片N、P化学计量特征及其与土壤N、P浓度的关系

测定了松嫩平原草甸3种主要植物羊草(Leymus chinensis)、芦苇(Phragmites communis)和尖叶胡枝子(Lespedeza hedysaroides)叶片全氮、全磷浓度,并分析了它们与土壤全氮、全磷浓度的关系.结果表明:3种植物叶片全氮浓度种间差异显著(P＜0.05),而全磷浓度种间差异不显...     

High concentration biotherapeutic formulation and ultrafiltration: Part 1 pressure limits

High therapeutic dosage requirements and the desire for ease of administration drive the trend to subcutaneous administration using delivery systems such as subcutaneous pumps and prefilled syringes. Because of dosage volume limits, prefilled syringe administration requires higher concentration liquid formulations, limited to about 30 cP or roughly 100–300 g L^?1 for mAb's. Ultrafiltration (UF) processes are routinely used to formulate biological therapeutics. This article considers pressure constraints on the UF process that may limit its ability to achieve high final product concentrations. A system hardware analysis shows that the ultrafiltration cassette pressure drop is the major factor limiting UF systems. Additional system design recommendations are also provided. The design and performance of a new cassette with a lower feed channel flow resistance is described along with 3D modeling of feed channel pressure drop. The implications of variations in cassette flow channel resistance for scaling up and setting specifications are considered. A recommendation for a maximum pressure specification is provided. A review of viscosity data and theory shows that molecular engineering, temperature, and the use of viscosity modifying excipients including pH adjustment can be used to achieve higher concentrations. The combined use of a low pressure drop cassette with excipients further increased final concentrations by 35%. Guidance is provided on system operation to control hydraulics during final concentration. These recommendations should allow one to design and operate systems to routinely achieve the 30 cP target final viscosity capable of delivery using a pre‐filled syringe. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:113–124, 2017