乳酸发酵动力学研究进展

对乳酸发酵过程中几种典型的发酵过程动力学,如游离细菌进行乳酸发酵动力学、海藻酸钙固定化米根霉的发酵动力学、转盘反应器固定化米根霉的发酵动力学以及聚氨酯固定化米根霉的发酵动力学进行了阐述。     

PVA共固定化双菌种发酵海藻酒的研究*

采用PVA为载体共固定化酿酒酵母和产香酵母发酵海藻,酿造海藻酒。对游离细胞与固定化细胞的分批发酵和连续发酵的动力学进行了研究并建立了相应的发酵动力学方程。实验结果表明：酿酒酵母和产香酵母二种菌种菌量的最佳配比为4：l,发酵温度20℃．共固定化细胞分批发酵和连续发酵凝胶粒的充填系数分别为0．25和0．5,游离混合细胞的发酵时间为7d。共固定化细胞连续发酵稀释速率0．12／h,其发酵时间为0.5d左右。经160d连续发酵实验,PVA固定化细胞粒子的机械强度良好。     

PVA共固定化双菌种发酵海藻酒的研究

采用ＰＶＡ为载体共固定化酿酒酵母和产香酵母发酵海藻,酿造海藻酒。对游离细胞与固定化细胞的分批发酵和连续发酵的动力学进行了研究并建立了相应的发酵动力学方程。实验结果表明：酿酒酵母和产香酵母二种菌种菌量的最佳配比为４∶１,发酵温度２０℃,共固定化细胞分批发酵和连续发酵凝胶粒的充填系数分别为０２５和０５,游离混合细胞的发酵时间为７ｄ,共固定化细胞连续发酵稀释速率０１２／ｈ,其发酵时间为０５ｄ左右。经１６０ｄ连续发酵实验,ＰＶＡ固定化细胞粒子的机械强度良好。     

固定化酵母酒精发酵动力学性质的初步研究

用固定化细胞连续发酵生产酒精是酒精发酵工艺的重大改革,有关这方面的研究已有许多报道,部分已完成了中试。不过、到目前为止,固定化酵母酒精发酵动力学性质方面的研究只有少数报道。本文用海藻酸钠固定化酵     

陶瓷载体固定化酵母发酵动力学研究

固定化细胞和固定化酶一样,作为固液两相的非均相催化反应系统,其反应速度无疑受到内外扩散的影响。世界各国的化学工程学者在固定化酶反应动力学方面研究得较多,固定化细胞反应动力学研究虽有些报道,但主要集中在以海藻酸钙为载体的固定化系统,且载体形状为球形颗粒。对于其他材料的不同形状颗粒载体的固定化细胞动力学研究报道较少。陶瓷作为固定化细胞载体是我们研究的一种固定化细胞的新型载体,在机械强度,孔径大小,细胞与之结合牢固度及其稳定活性,再生性能方面有其特有的优越性^[10]。为了给在生产实践中使用这种新型载体提供理论依据,本文采用球型陶瓷和拉西环陶瓷为载体固定化酵母,对它们的发酵动力学进行了比较研究。     

固定化对酵母细胞发酵产ATP能力的影响

通过试验对酵母菌细胞的固定化方法及固定化酵母细胞在发酵生产ATP方面的应用进行了探讨。综合固定化颗粒的性能指标(粒径、弹性和机械强度)和发酵产ATP的能力,通过正交试验对酵母菌细胞的包埋条件进行了优化,确定了固定化酵母细胞的较优组合为聚乙烯醇3.5%、海藻酸钠2%、CaCl23%及交联时间6h,发酵后ATP含量最高,达到0.716g/L。进一步发酵条件的试验证实,固定化能提高酵母菌细胞对温度适应范围,延长发酵生产周期,从而提高菌体的利用率。     

固定化根霉发酵生产脂肪酶

以聚氨酯为少根根霉固定化载体,对固定化后的细胞连续重复批次发酵进行了研究。优化了重复批次发酵培养基组成。在取代发酵液40mL,取代培养基组成为全脂豆粉3%,花生油0.5％条件下,固定化菌体摇瓶实验可连续使用140h,重复9批次。酶的时空产率提高6倍。5L发酵罐小试固定化菌体可连续发酵6批次。固定化细胞连续发酵,大大缩短了发酵的时间,酶的时空产率获得大幅提高。     

固定化酵母乙醇发酵及固化小球微生态的研究

比较了SA-PVA-SiO₂固定化酿酒酵母和游离酿酒酵母的乙醇发酵能力,采用批次发酵试验研究固定化酿酒酵母的发酵稳定性。结果表明,SA-PVA-SiO₂固定化酿酒酵母的发酵速度比游离酿酒酵母快,发酵周期短;发酵稳定性很好,30℃,橡胶塞、90 r/min摇床培养24 h时,乙醇体积分数均在3%~3.5％之间,连续发酵14批次后,固化小球的形态依然完好,不发粘。通过扫描电镜对酿酒酵母包埋微生态环境进行了分析,图像表明固定化小球的内部环境非常有利于酵母细胞的厌氧发酵产乙醇,充分证明了SA-PVA-SiO₂固定化酿酒酵母乙醇发酵的优越性。     

固定化酵母反应动力学的研究

本文采用微分反应器初速度法对以海藻酸钙为载体的固定化酵母的耗糖动力学进行了研究。测得了固定化酵母的表观动力学常数,并进一步求得了固定化酵母的本征动力学常数。实验结果表明,固定化酵母的表观动力学常数显著受内外扩散的影响,其本征动力学常数与 游离酵母的动力学常数比较,也有较大的不同。此外,对内扩散对反应动力学的影响进行了理论分析和实验验证。     

固定化米根霉生产L－乳酸的研究

开发了利用聚氨酯泡沫为载体固定化米根霉生产Ｌ－乳酸的新工艺。确定了固定化细胞发酵条件：葡萄糖浓度为５０ｇ／ｌ,载体立方体边长为４～８ｍｍ,载体量为２０ｃｍ３／７０ｍｌ培养基,固定化细胞制备培养时间为２４ｈ．利用固定化细胞发酵产酸速率是游离菌的３倍以上,对糖转化率达７７．７０％,与理论转化率相近。该固定化细胞应用在反复间歇发酵中可稳定１０批次以上。     

Échinodermes de l'Ordovicien supérieur (Ashgill) de Sardaigne et d'Algérie

Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.     

果实膨大期喷布磷酸二氢钾对三月红荔枝果实贮藏性的影响

在三月红荔枝(Litchi chinensis cv.Sanyuehong)果实膨大期对树冠喷施0.2%磷酸二氢钾(KP)水溶液,以探讨磷酸二氢钾对荔枝果实贮藏性的影响。结果表明:(1) KP处理的果实在贮藏期前17d,失重率及果肉可溶性固形物、酸、VitC、花色素苷等指标的变化趋势与对照基本相似;(2) KP处理的果肉可溶性蛋白质含量变化与对照有明显差异,而果皮的可溶性蛋白质含量在贮藏期前10d变化动态与对照一致,此后呈相反的变化趋势;(3)果皮POD活性显著高于果肉,KP处理和对照的果肉POD活性在贮藏第3d后、果皮POD活性在第17d前分别具有相似变化趋势;(4)果肉中CAT活性在贮藏第3~17d期间都显著或极显著高于果皮,KP处理和对照果肉、果皮CAT活性动态变化均为单峰曲线。     

A reassessment of the relations in Malaysia between ants (Crematogaster) on trees (Leptospermum and Dacrydium) and epiphytes of the genus Dischidia (Asclepiadaceae) including 'ant-plants'

Three species of epiphytic Dischidia have been investigated in terms of their relationship to ants on trees. Two species, D. parvifolia and D. astephana , are associated with ants and trees in montane areas. A clear association has been found between ants of the genus Crematogaster and the tree Leptospermum flavescens. This relationship is complex and probably both organisms benefit from the association. The ants live in tunnels in the wood of the major branches and the trunk, and the entire tree is occupied by one ant colony. Trees occupied by ants are maintained by the ants substantially clear of epiphytes other than the two species of Dischidia. The potential benefits to the tree and to the ants of this association are noted. The roots of D. astephana and D. parvifolia penetrate into the cavities of these ant nests and presumably gain nutrients from waste in the ant nests. Both Dischidia species are effectively scavenging upon the waste material from the ant-tree association. The leathery dome-shaped leaves of D. astephana are not vital to the development of the scavenging habit as D. parvifolia has lens-shaped leaves, but may offer some advantage to D. astephana by the uptake of nutrients from waste deposited by the ants under the dome-shaped leaves by interception of stem flow and by uptake of gaseous waste. Ants do not nest under these leaves. Seeds of these species of Dischidia are taken by ants into the central woody area of the ant nest where they germinate. Both Leptospermum and Dischidia can be visualized as showing adaptations to a nutient-deficient tropical montane environment. These adaptations are discussed as is the need for reassessment in this genus of the term 'ant-plant', and the need for wider recognition of the 1ant-tree' relationship between Crematogaster and Leptospermum.     

The influence of mass,volume and density on the frequency of recovery of fossil hominid hand and wrist bones

A study of the mass, volume and density of each of the wrist and hand bones of male and female human skeletons was undertaken. It was found that the mass and volume (i.e. size) of the bones are well correlated with the relative frequencies of preservation ofAustralopithecus and earlyHomo wrist and hand bones from fossil hominid sites in Africa. In general, the larger the bone, the greater its preservation frequency. In contrast to findings on bovid bones, the density of hand and wrist bones is not well correlated with the frequency of such bones recovered from these sites. These findings may be explained in terms of the agents of deposition of the bones, the physical nature of the deposit, and the methods of extraction of the fossils from the deposit.     

An Ultrastructural Study on the Development of Egg- apparatus in Rice Embryo Sac

The development of the egg-apparatus (consisted of an egg cell and two synergids) of rice ( Oryza sativa L. ) was studied at the uhrastructural level. The walls of the egg cell and synergids, immediately after their formation, possessed numerous plasmodesmata. Plasmodesmata were also present on walls between the egg cell and synergids. During the enlargement phase of the egg cell and synergids, the walls at the tip region began to loosen and vesiculate. By the time the embryo sac became mature, the part of the wall of the egg cell and synergids, facing the chalaza, disappeared. Consequently, the tip regions of the egg cell and synergids were only protected by a plasma membrane. When the embryo sac reached full maturity, the upper and middle region of the wall of the synergids broke up into pieces. At that time one synergid began to degenerate. Plasmodesmata persisted at the hook region of the wall of both the egg cell and synergids. Most plastids in the egg cell contained starch grains that persisted throughout the period of the embryo sac development. Starch grains in the plastids of the synergids appeared only before the time when the two polar-nuclei moved into the region above the egg-apparatus. They then disappeared and did not appear again until the embryo sac had reached full maturity. The size and location of the vacuoles in the egg cell were different from those in the synergids. The time of formation was also different. Vacuoles in the egg cell formed late in comparison with the synergids. Vacuoles in the chalazal region of the egg cell (especially at the early stage of the embryo sac development) were much larger than those in the micropylar region. Vacuoles in the synergids tended to concentrate mainly in the chalazal region. There was a peak period of lipid formation in the two synergids. The peak appeared when the embryo sac neared maturity. At the early stage of development, the nuclei of the synergids were elliptical in shape and were situated at the central region near the micropyle. The shape of the nuclei at the late stage of development became less regular and tended to move more towards the micropylar region. Changes in the uhrastructure of the egg cell and synergids of rice appeared to be closely related to the metabolic processes controlling the embryo sac formation and development.     

Germination and development of Mimosa pilulifera in petroleum-contaminated soil and bioremediated soil

In 2000 there was an oil spill at the Getúlio Vargas Refinery (REPAR/PETROBRÁS) in Paraná, Brazil. Nearly five years after contamination and the use of bioremediation, a study was carried out to identify the effects of the contaminated soil and the bioremediated soil on the germination and initial growth of Mimosa pilulifera seedlings. The experiment consisted of three treatments: petroleum-contaminated soil, bioremediated soil and uncontaminated soil, with five repetitions each. The following measurements were taken after 30, 60 and 90 days of planting: the percentage of germination, biomass and leaf area of the eophylls, biomass and length of the shoot and the roots in addition to the shoot/root ratio. The percentage of germination and the root biomass were not affected by the contaminated soil or by the bioremediated soil. On both the contaminated soil and the bioremediated soil biomass and leaf area of the eophyll were reduced. Plant length and shoot biomass were lower in the contaminated soil. Furthermore, the effect of the contaminated soil and the bioremediated soil was greater in the shoot than in the root system, since the bioremediation reduced the toxicity of the petroleum-contaminated soil.     

略论棕榈科与新分出的省藤科的系统分类、演化、区系地理及主要的经济用途

棕榈科原省藤亚科因其子房壁及外果皮被倒生、螺旋状排列的鳞片所覆盖,而区别于其他亚科,因而独立分出成一新科--省藤科。作者讨论了棕榈科的祖先种可能在石炭纪时,自原始裸子植物开以顿目在分化、衍生出苏铁目祖先种的进化干上,于白垩纪时分化出的一个分支。在棕榈科的祖先种出现不久后,在其进化的分支上,于白垩纪后期又分化出一旁支,成为棕榈科的姊妹科--省藤科的祖先种。从两祖先种分别再分化、衍生出现今分布地球上该二科的属与种。两科、尤其前者是被子植物、尤其是单子叶植物中最原始的类群之一。作者还提出棕榈科象牙椰亚科与贝叶棕亚科是该科最原始或较原始的两类群;槟榔亚科和腊材榈亚科是较进化的两类群;而水椰亚科祖先种可能源于象牙椰亚科的祖先种,但又演化为该科最进化与特化的类群。省藤科省藤亚科略比鳞果榈亚科原始。作者讨论了两科为泛热带分布的科,指出两科的"现代分布区"在南北两半球热带地区,少数种还延伸分布到两半球暖亚热带、甚至达中亚热带地区,分布区边缘最北达日本中部、中国长江流域及黄河下游的南部,美国加利佛尼亚州与佛罗里达州和地中海北部;最南达智利中部和新西兰南部;而"现代分布中心"在热带与暖亚热带的亚洲,中、南美洲,大洋洲及非洲的东、南、西部;但分布区的"密集中心"则在热带亚洲、热带中及南美洲、南太平洋群岛及非洲东南部。作者还介绍了近50年我国南方引种驯化成功的两科植物近400种(见^*图谱),其中少数为耐寒的种类,有的种已引种到长江流域或更北的地区。引种的大部分种都有其重要的经济用途,包括:1. 食用,如淀粉和树液可制"西米"或制糖,酿酒、醋或作饮料;果或种子榨油,供食用或工业用;某些种的嫩芽作蔬菜,甚至种子代咖啡饮用;2. 药用,有消炎、止血、活血、驱虫、抗癌等用;3. 建筑、工艺与日用品,包括不少种的树干供建普通房子、桥梁、小船;少数种可提制工业用蜡;许多种的纤维制高级缆绳和编织品;还制工艺品与日用品等;4. 代表热带景观的园林工程、绿化及美化环境的观赏树和人行道树及建造园林景观生态类型的树种等。     

Food availability and growth rate in natural populations of the brown trout (Salmo trutta) in Corsican streams

The rivers of the island of Corsica, whose catchment areas are on crystalline rock, have low salt contents and their invertebrate fauna is qualitatively and quantitatively poorer than on the European mainland. The growth rate of trout in Corsica was analysed on samples from of six coastal rivers: the Tavignano, the Fium Orbo and the Golo on the west coast, the Prunelli, the Taravo and the Rizzanese on the east coast. Mesological data — conductivity, temperature, calcium content and altitude and biological data — biomass and linear growth rate of the trout, and density of benthic invertebrates — were collected at each of the sampling station.Analysis of variance of the size of three year old trout revealed three groups of rivers. The first includes the Tavignano, the Rizzanese and the Taravo, where the highest linear growth rates were recorded; the second consists of the Golo and the Prunelli, and the third, of the Fium Orbo. Principal component analysis gave two main axes on the basis of temperature and benthic invertebrate density for the first, and trout biomass for the second. Linear regression showed that benthic invertebrate density accounted for 75% of size variance of three year old trout. Evidence of the limiting role of the trophic factor is provided.     

Recent advances and prospects in Prunus virology

The stone fruit genus Prunus, within the family Rosaceae, comprises more than 230 species, some of which have great importance or value as ornamental or fruit crops. Prunus are affected by numerous viruses and viroids linked to the vegetative propagation practices in many of the cultivated species. To date, 44 viruses and three viroids have been described in the 9 main cultivated Prunus species. Seven of these viruses and one viroid have been identified in Prunus hosts within the last 5 years. This work addresses recent advances and prospects in the study of viruses and viroids affecting Prunus species, mostly concerning the detection and characterisation of the agents involved, pathogenesis analysis and the search for new control tools. New sequencing technologies are quickly reshaping the way we can identify and characterise new plant viruses and isolates. Specific efforts aimed at virus identification or data mining of high‐throughput sequencing data generated for plant genomics‐oriented purposes can efficiently reveal the presence of known or novel viruses. These technologies have also been used to gain a deeper knowledge of the pathogenesis mechanisms at the gene and miRNA expression level that underlie the interactions between Prunus spp. and their main viruses and viroids. New biotechnological control tools include the transfer of resistance by grafting, the use of new sources of resistance and the development of gene silencing strategies using genetic transformation. In addition, the application of next generation sequencing and genome editing techniques will contribute to improving our knowledge of virus–host interactions and the mechanisms of resistance. This should be of great interest in the search to obtain new Prunus cultivars capable of dealing both with known viruses and viroids and with those that are yet to be discovered in the uncertain scenario of climate change.     

Manipulation of xylem transport affects Zn and Mn transport into developing wheat grains of cultured ears

Zinc and manganese loading into developing wheat grain is little understood at present. The objective of this work was to investigate factors that may affect the rate of transport of Zn and Mn into developing wheat grain of cultured ears. Ears 18-22 days post-anthesis were cultured in solutions containing labelled Zn and Mn. The effect of additions of Cu, Fe, citrate, malate and EDTA to the culture solution was observed. The effect of humidity and awn removal as well as the sucrose status of the ears on Zn and Mn transport was also investigated. The effect of high concentration of Zn and Mn on [¹⁴C]-sucrose transport was determined. High humidity almost completely blocked transport of Zn and Mn into the grain. Awn removal reduced the transport of Zn and Mn to the lemma but not the grain. When the ears were depleted of sucrose (by maintaining them in the dark prior to labelling) transport of Zn and Mn to the grain was reduced compared to ears cultured with sucrose. The presence of Cu reduced the loading of Zn into the grain. There was little effect of Cu on Mn transport or Fe on either Zn or Mn transport. High concentrations of Zn and Mn in the culture solution did not affect [¹⁴C]-sucrose loading into the grain but loading of Zn and Mn was limited at high concentrations suggesting membrane saturation. This study demonstrates that sucrose status and humidity clearly influence the transport of Zn and Mn into the grain, and that other ions may influence Zn and Mn transport.