木薯固定化酵母酒精发酵技术的研究进展

现有的研究表明,木薯固定化酵母酒精发酵技术生产酒精相对于游离酵母发酵具有明显的优越性。本文综述了木薯固定化细胞酒精发酵技术的研究进展,主要包括菌种,载体的选择,酵母固定化方法,固定化酵母生物反应器以及木薯固定化酵母酒精发酵工艺等。     

Thermobifida fusca海藻糖合成酶基因的克隆表达及发酵优化

将来源于嗜热单孢菌(Thermobifida fusca)的海藻糖合成酶基因进行克隆表达,构建重组菌E.coli BL 21(DE3){pET-24a(+)/Tres}。并对基因工程菌的发酵产酶条件进行优化,得到最优培养基成分为:甘油12 g/L,酵母粉24 g/L,蛋白胨12g/L,磷酸盐浓度60mmol/L,Zn2+2mmol/L。最佳培养条件为:装液量20 ml(250 ml摇瓶),发酵2 h后25℃诱导并添加终浓度为0.4 mmol/L的IPTG。优化后的最终发酵酶活达到28.6 U/ml,为未优化前的3.4倍,是目前国内报道大肠杆菌摇瓶发酵产海藻糖合成酶的最高表达水平,为该酶的工业化生产奠定了基础。     

酵母生长过程的热谱研究

报道了用自制的 DDC- 型补偿式数字精密量热系统 ,对酵母细胞生长繁殖过程的热效应进行了跟踪监测 ,获得了过程的热谱图 .对比分析用量热法获得的酵母生长过程的热谱图和用传统记数法获得的酵母生长过程的生长曲线 ,两者是一致的 .同时通过对热谱图的进一步分析 ,可得到比生长曲线更多的酵母生长繁殖过程的微观信息 ,不仅为研究酵母的酵化和能量代谢过程提供了理论依据 ,而且从量热学角度为研究酵母生长过程提供了一种新的方法     

生物表面活性剂合成的促产因子研究进展

生物表面活性剂是微生物产生的一类具有表面活性的代谢产物,与化学表面活性剂相比,具有高效、低毒、易降解的优点。本文综述了氨基酸、酵母提取物、金属离子和有机酸作为促产因子时,对生物表面活性剂产量、结构和同系物组成影响的研究进展,并对其促产机理进行了归纳总结,最后对此领域的研究进行了展望。     

酒糟生产酵母培养物的固态发酵工艺研究

提出了利用酒糟制备酵母培养物,既可以作为饲料蛋白,又可以作为动物益生因子。确定了最佳发酵工艺条件。     

重组毕赤酵母(Pichia pastoris)高产Lunasin的发酵工艺优化

Lunasin是一个最初从大豆中分离,具有43个氨基酸的多肽,具有抗高血压,抗氧化活性,预防癌症,抗炎和降胆固醇的活性。为了实现Lunasin的高效生产,对重组毕赤酵母GS115 LN诱导阶段甲醇补料策略(溶氧反馈补料,指数-恒速补料)以及诱导温度进行了优化,并且在此基础上对双碳源(山梨醇、甘露醇)和甲醇混合补料策略以及复合氮源与甲醇混合补料策略进行了优化。研究表明,最优补料策略以及诱导温度分别为指数-恒速补料、24℃,最终在流加1%大豆蛋白胨以及0.02%天冬氨酸条件下,Lunasin表达量最高,达到3.27 g/L,是单一甲醇诱导的1.27倍。     

日粮添加酵母产品对断奶仔猪肠道功能、血清和回肠黏膜氨基酸含量的改善作用

断奶与仔猪肠道和免疫功能障碍有关,日粮中添加酵母产品能改善肠道黏膜结构和刺激断奶仔猪免疫系统。研究旨在验证日粮补充酵母产品可以通过改善断奶仔猪肠道功能和营养水平以达到调节免疫球蛋白产生的目的。选取21日龄断奶仔猪18头,随机分配到3个处理组,对照组饲喂基础日粮,另外两组分别在基础日粮中添加酵母产品1.2 g·kg-1或添加硫酸粘杆菌素(抗生素)20 mg·kg-1,试验期为14 d。日粮补充酵母产品或抗生素均显著提高了断奶仔猪十二指肠和回肠黏膜中分泌型Ig A(SIg A)以及血清总蛋白、Ig G和Ig M的含量(P<0.05)。与对照组相比,饲喂添加酵母产品日粮的仔猪血清中异亮氨酸、亮氨酸、苯丙氨酸、脯氨酸含量显著升高(P<0.05),并且回肠黏膜中精氨酸、组氨酸、亮氨酸、赖氨酸、色氨酸、缬氨酸、丝氨酸、谷氨酸、谷氨酰胺和脯氨酸的含量也显著增加(P<0.05),随着氨基酸(AA)含量的增加,仔猪回肠碱性磷酸酶活性和AA转运蛋白的表达均显著增加(P<0.05)。结果表明,酵母产品通过改善肠道功能和营养物质水平可增强断奶仔猪免疫球蛋白的产生,说明酵母菌产品可能成为断奶仔猪日粮中抗生素的一种替代品。     

二级曝气生物滤池中碳、氮代谢特性的研究

采用以高分子生物载体为填料的二级曝气生物滤池处理生活污水,研究了进水有机负荷和NH3-N负荷对系统处理效果的影响.结果表明,在水温为18-25℃、pH值为5.8-7.4、气水比为3.5:1时,对COD的去除率与进水有机负荷呈正相关,硝化率同有机负荷及NH3-N负荷呈负相关,且主要取决于前者.当有机负荷为2.75-3.90kg/(m3.d)时,对C0D的去除率可高达98%;当有机负荷为0.77-1.48kg/(m3.d)时,硝化率可达93.3-98.1%,对TN的平均去除率达39.4%.降低进水有机负荷可解除高负荷所导致的硝化抑制作用,使硝化的起始点提前,提高峭化率,显示出单独驯化的硝化滤池在去除NH3-N上的优势.硝化菌受反冲洗的影响大于异养菌,反冲洗6h后系统可基本恢复时COD和NH3-N的去除效果.     

寒冷地区厌氧塘的底泥特性及蓄积量预测

准确预测厌氧塘的底泥沉积量对于保证其稳定运行有重要意义，为此对寒冷地区厌氧塘底泥的成因及降解进行了分析，并建立了较为可行的底泥蓄积量预测模型，在实测数据的基础上，得出了齐齐哈尔和安达市的厌氧塘蓄积量修正系数，同时分析了其污泥特性。     

基于聚集指数测度的上海市流动人口分布特征分析

提出以"聚集指数"来描述流动人口聚集程度的方法:利用上海市五普数据对流动人口空间聚集特征进行分析, 揭示了上海市流动人口空间分布特征.分析结果表明,上海流动人口空间分布特征为"环状"与"放射状"相叠合:而社会空间分布特征是流动人口集聚空间与城市户籍居民中的劳动者阶层、初中以下人群、25-44岁年龄群体在空间分布上存在较高的相关性, 即流动人口进入城市进一步加剧了城市社会阶层、教育程度、年龄结构等社会因子的分异程度.     

从集聚到紧凑：香港港铁站域空间居住建筑分布特征研究

站点周边居住建筑的密度直接影响乘坐轨道交通的总量,轨道站域范围内居住建筑分布的整体比重与轨道交通分担出行的比例相关。针对香港74个港铁站域空间居住建筑形态特征的研究重点分析了居住单元的分布情况,站域范围的居住建筑的密度与港铁乘坐量密切相关;站域空间范围的分布情况与非轨道站影响区域的比较发现,以轨道站为核心的居住建筑集聚特征是支持香港轨道系统高效率的重要空间特征之一。围绕轨道站的居住建筑集聚能够通过居民出行活动的集聚引导商业和社会服务设施分布密度的提高,是促进紧凑空间形态的形成的基本动力。归纳在轨道系统建设、站域空间发展的不同阶段影响紧凑形态形成的各类因素,有利于合理制定以轨道站为导向的紧凑城市空间形态策略。     

Accumulation of nitrous oxide in aerobic groundwaters

N₂O concentrations in the groundwaters collected in the Kanto District and Nagano Prefecture in Japan and five counties in New York State were determined. These N₂O data were obtained from the water samples from wells, springs and seepages from soils in forests and cropping fields. The N₂O concentrations in all samples greatly exceeded those of atmospheric equilibration. The average concentration of 690 nM N₂O is one order of magnitude larger than that in deep ocean. All groundwaters of the present study were aerobic with a high level of NO₃⁻, but with the absence of NO₂⁻ and NH₄⁺, and with a very low level of dissolved organic carbon. These characteristics suggest that the nitrate respiration in the aquifers is of little significance for the production of N₂O.

ΔN₂O/NO₃⁻ molar ratios in the groundwaters were between 10⁻⁴ and 10⁻² (Δ indicates the excess gas over that which would be in equilibrium). This supports the above view since the observed N₂O yield agrees with that reported for the production during an ammonia oxidation. If nitrification was indeed a major mechanism for the production of groundwater N₂O, subsequent release of N₂O from the aquifers that are polluted with nitrogen may deserve more close attention as a potential source of atmospheric N₂O via diffusion and discharge.     

南美亚诺斯盆地油气成藏条件与成藏模式

南美亚诺斯盆地是南美甚至世界范围内重要的富油气盆地,通过对亚诺斯盆地油气成藏条件的分析,并结合盆地内构造演化、沉积作用影响,揭示了亚诺斯盆地内油气成藏特征,建立了油气成藏模式。亚诺斯盆地经历了古生代被动大陆边缘、中生代弧后裂谷、新生代前陆盆地3个构造演化期,发育多套烃源岩及储盖组合,圈闭类型多样,油气分布复杂,具有良好的勘探开发前景。盆地油气成藏具有远距运移,混源充注,断砂立体,持续输导,阶梯式捕集成藏的特点;主力产层渐新统卡沃内拉组表现为近灶优先捕集形成中深层大中型构造油气田,远灶接替捕集形成浅层小型复合型油气田的油气分布规律。取得的认识对亚诺斯盆地进一步的油气发现具有重要的借鉴意义。     

Metabolic activity in cores of lake-bottom sediments

The catabolic activity of various levels of lake-bottom sediment cores (from 0 to 10 at 2.5-cm intervals) was measured by the production of ¹⁴CO₂ from radioactively-labelled substrate at in situ temperatures. All levels of sediment were found to possess activity, which decreased with core depth, except the 7.5- and 10.0-cm levels of the March core. This lack of activity was shown to be due to the relatively low in situ temperature for the March core. An anabolic activity profile indicated that a considerable degree of anabolism occurred at various core levels. It was also found that the non-biological binding that occurred at the different core levels decreased with core depth, which may be related to the measured decrease in particulate matter with core depth. The addition of soluble nitrogen to the July sediment core resulted in an increased nitrogen concentration in the sediment and a concomitant increase in catabolic activity.     

Intracellular interaction and biotransformation of arsenite in rats and rabbits

The accumulation of arsenic with time in tissues of rats and rabbits was determined by neutron activation analysis (NAA). Rats showed a steady increase in the As-concentrations with age, whereas in rabbits it was nearly the same for adults and in young animals. The metabolism of arsenic was studied in both animal species after i.p. injection of 50/μg As/kg b.w. as ⁷⁴As labelled arsenite. Eight tissues, as well as blood and urine, were analysed for ⁷⁴As content after 16 and 48 hours. The binding of ⁷⁴As to hematic and intracellular components and the chemical forms of arsenic in tissues and urine were investigated. In the plasma and the RBC-fraction of the rabbit, the As concentration decreased during the first two days, while in the rats it only disappeared from the plasma, but was retained in the RBC-fraction. Liver, kidney and lung of rabbits with the highest As concentrations at 16 and 48 hours showed a rapid clearance of As in the first 48 hours. In the corresponding tissues of the rats, the rate of decline was significantly lower, due to the higher binding of ⁷⁴As to tissue constituents. Poor binding of As to plasma proteins was seen in rabbits while in rats it was totally bound to this fraction. In the RBC, liver and kidney cytosols, however, the affinity of As for intracellular proteins was higher in both animal species but characterized by a rate of binding different between the two animal species. The amount of dimethylarsinic acid (DMA) in the tissues was significantly lower in the rat than in the rabbit, reflecting the total amount of diffusible arsenic, which was also much lower in the tissues of rats than in rabbits.