高山红景天细胞悬浮培养生长和营养成分摄取动力学及其…

探讨了高山红景天细胞悬浮培养过程中生长及主要营养成分摄取的动力学，计算了碳源，氮源对生物量的得率系数，通过对细胞基本元素组成的分析，建立了细胞生长的基本计量方程，并从理论上测算出得率系数和呼吸商，最后，从碳平衡及氧平衡方程建立了细胞生长速率，底物摄取速率与Ｏ２消耗速率及ＣＯ２排出速率之间的关联式。     

Fe3+对赤潮异弯藻生长和光合作用的影响

用人工海水APSW以f／2营养加富，在总铁浓度为0—1000nmol L^-1的范围内，考察了总铁浓度对赤潮异弯藻(Heterosigma akashiwo)生长和光合作用的影响．结果发现，当铁浓度小于10nmol L^-1时，最大藻细胞密度与比生长速率均受到明显限制．补铁后受铁限制的细胞得到缓解，表明铁是藻细胞生长的重要限制因子．当铁浓度大于100nmol L^-1时，最大细胞密度与比生长速率不再受铁限制，但其光合作用活性有所改变．在铁限制下细胞的光饱和光合作用速率Pm，暗呼吸速率Rd，表观光合作用效率a与铁丰富细胞相比都有所减小，而光补偿点Ic及饱和光强Ik增大．图5表1参11     

不同氮磷水平下中肋骨条藻对营养盐的吸收及光合特性

研究了不同氮、磷水平下中肋骨条藻(Skeletonema costatum)对营养盐的吸收动力学、生长和光合作用特性，结果表明，培养基中氮或磷浓度的改变对中肋骨条藻比生长速率影响不大，各种条件下藻细胞的比生长速率约为1．51—1．60d^-1，其中，藻细胞在低氮条件下的比生长速率略高，为1．60d^-1；低氮和低磷条件下藻细胞稳定期的生物量明显下降，分别比中氮和高氮下减少了27％和41％，而比中磷和高磷减少了64％和65％,低营养源(低氮或低磷)状态下生长的藻细胞具有较低的单位细胞表示的光饱和的光合作用速率(Pm^cell)和光合效率(α^crll)。尽管在低氮或低磷条件下生长的藻细胞单位叶绿素a的含量较低，但具有较高的活性，以单位叶绿素a表示的光饱和的光合作用速率(Pm^chla)和光合效率(α^chla)均与高氮或高磷条件下生长的藻细胞相当，这可能是不同氮、磷水平下比生长速率差异不大的原因．中肋骨条藻细胞对氮和磷吸收的适当比值(N／P)为0．8-2．6．图3表4参17     

欧洲红豆杉细胞培养的研究

从欧洲红豆杉（Ｔａｘｕｓｂａｃｃａｔａ）的嫩茎及什叶诱导出愈伤组织，并对之进行了愈伤组织培养及细胞悬浮培养研究；利用ＨＰＬＣ方法测定了培养物合成紫杉醇的能力．探索了提高培养细胞生长率及紫杉醇含量的一些措施．结果表明，欧洲红豆杉愈伤组织及悬浮培养细胞的生长速率已分别达到０．２７ｇ·Ｌ－１·ｄ－１和０．３５ｇ·Ｌ－１·ｄ－１，紫杉醇含量分别为０．００３１％和０．０１７％。     

灵芝深层发酵生产胞外多糖和灵芝酸的动力学分析

利用Sigmoidi函数构建了灵芝深层发酵生产胞外多精和灵芝酸的非结构动力学模型,并根据Boltzmann拟合求解出模型参数,模型预测值能够较好地吻合实验所测值.细胞最大比生长速率цmax为4.63x10-2 h-1,葡萄糖最大比消耗速率qs,max为6.70x10-2 h-1,胞外多糖最大比合成速率qEPs,max为4.65x10-3h-1,灵芝酸最大比合成速率qGA,max为9.09xlO-4 h-1.灵芝胞外多糖的合成与细胞的生长呈现部分偶联关系;灵芝酸的合成与细胞的生长呈现偶联关系,偶联系数αGA为0.020 4 g g-1.胞外多糖对葡绚糖的最大得率系数(YEPS/S)为O.214 g g-1;灵芝发酵40～80 h代谢碳流迅速从菌体自身生长迁移至胞外多糖合成,用于合成胞外多糖的最大碳流为23.60/0.     

三种载体上生物膜硝化作用动力学初步研究

通过测定水中COD、：NH4^ —N、NO2^-—N及NO3^-—N的浓度变化，研究了淹没式废水处理装置中沸石、活性炭和沙粒3种载体上硝化作用生物膜的动力学过程和反硝化作用。结果表明，3种载体上生物膜降解有机物(以COD表示)的过程可用一级动力学方程描述，反应速率常数分别为：沙粒0．0848h^-1、活性炭0．1187h^-1、沸石0．1334h^-1。3种载体上生物膜去除氨态氮的过程则可用零级动力学方程描述，反应速率常数分别为：沙粒-0．7743h^-1、活性炭-0．9886h^-1、沸石-1．0714h^-1．附着于沙上的生物膜去除亚硝酸盐氮的过程也可用零级动力学方程描述，反应速率常数为-0．6057h^-1，水中硝酸盐氮浓度较高时，载体沸石和活性炭上可能附着生长反硝化菌。图5表2参15。     

紫花苜蓿品种间根系发育过程分析

从根系发育角度分析了不同紫花苜蓿品种在甘肃黄土高原丘陵沟壑区的适应性．研究表明：品种间侧根发生总数差异较大，Ameristand201和Sandili均为14个，陇东苜蓿(Longdong)仅为6个，65％的侧根发生于营养生长阶段；品种间主根生长，根系体积、根系生物量的积累在各个生育期的表现分为3种类型，Ameristand201，Sandili，Ameri-graze401在整个生育期内的生长速率较快，且速率基本保持一致；陇东苜蓿，Derby，Sitel在整个生育期内生长速率较慢，但在盛花期(7月中旬)后，生长速率急剧增加；Goldenempress，Defi，Algonqiun介于前两者之间．从根系发育过程分析，Amefistand201，Sandili，Amerigraze401对黄土高原丘陵沟壑区的季节性降水反映相对迟钝，在干旱半干旱生境中具有较好的适应性．     

大气化学非均相反应摄取系数的测定

摄取系数是表征大气非均相反应的重要物理化学参数,也是大气颗粒物表面摄取气体能力的重要量化指标.本文综述了摄取系数的主要概念、主要测定方法和影响因素,以NaCl与NO2非均相反应为例,讨论了用漫反射傅立叶转换红外原位反应器扩散实验方式测定反应摄取系数的方法和误差,分析了气体扩散深度与红外穿透厚度对测定结果的影响,并测定了初始反应摄取系数.     

阿特拉津降解菌的生长规律及降解特征的实验

应用了从农药厂阿特拉津生产车间污泥中分离出的菌种AT菌，进行了菌种生长曲线的测定，求得AT菌的对数期代时为3．87d，生长速率为0．258d^-1；不同基质浓度的降解实验表明，在农药污染质阿特拉津的低浓度体系中，AT菌降解阿特拉津的反应符合一级动力学模式，属于米氏方程曲线的第一阶段的情形，并拟合出关系式V＝0．064S。     

聚苯乙烯泡沫中六溴环十二烷(HBCD)释放速率测定方法

本研究构建了适用于测定材料中半挥发性有机物释放速率的新型释放池装置,采用此释放池装置测定发泡聚苯乙烯(EPS)泡沫板中六溴环十二烷(HBCD)在60℃条件下的释放速率,并建立了HBCD的挥发释放模型.3种主要的HBCD非对映体(α-HBCD、β-HBCD和γ-HBCD)的释放行为并不存在明显差异;HBCD在吹扫气体中的浓度在前12 d逐渐增加,然后趋于稳定状态.HBCD在吹扫气体和释放池内壁间存在分配平衡,指数方程可以很好描述HBCD在释放池内壁的吸附水平与其在吹扫气体中浓度水平之间的关系.EPS在60℃条件下HBCD的释放速率为246.5 ng·m~(-2)·d~(-1).释放模型模拟结果表明,HBCD在60℃条件下的释放主要依赖于其材料-气相分配系数K和对流传质系数h_m,基本不受内部扩散系数D值的影响.     

The rapid response of the marine diatom Skeletonema costatum to changes in external and internal nutrient concentration

A nitrogen-deficient batch culture of the marine diatom Skeletonema costatum, when resupplied with a mixture of nitrate and ammonium, showed an initial enhanced nitrate uptake rate leading to a large internal concentration (pool) of nitrate. Following this initial nitrate uptake event, nitrate uptake ceased, and nitrate assimilation was inhibited until the ammonium present was used. At this point, nitrate uptake resumed and nitrate assimilation began. No internal ammonium pool was observed during nitrate utilization, but a large nitrate pool remained throughout the utilization of external nitrate. The internal nitrate pool decreased rapidly after exhaustion of nitrate from the culture medium, but growth of cellular particulate nitrogen continued for about 24 h. A mathematical simulation model was developed from these data. The model cell consisted of a nitrate pool, ammonium pool, dissolved organic nitrogen pool, and particulate nitrogen. It was found that simple Michaelis-Menten functions for uptake and assimilation gave inadequate fit to the data. Michaelis-Menten functions were modified by inclusion of inhibitory and stimulatory feedback from the internal pools to more accurately represent the observed nutrient utilization.     

稀土对沙田柚叶片营养和果实品质与产量的效应

试验结果表明,适量施用稀土可提高沙田柚树体对营养元素的吸收,促进养分平衡,从而可提高沙田柚座果率和产量,而且对柚果还有增糖降酸的效果。因此,适时适量施用稀土对提高沙田柚产量和品质均有积极的意义。     

Temperature tolerance of embryos and larvae of five bivalve species under simulated power plant entrainment conditions: a synthesis

Upwelling effects of subsurface water on phytoplankton growth were evaluated by 9 simulated culture experiments of coastal upwelling. Particular attention was paid to the effects of nutrient enrichment on the surface phytoplankton by the upwelling of nutrient rich subsurface water and of the exposure of the subsurface phytoplankters to surface radiation. The following are the results obtained: the lag period of phytoplankton growth was inversely related to water temperature; the maximum yield of phytoplankton was proportional to the amounts of available initial nutrients; the specific growth rates of phytoplankton were a function of both the initial nutrient concentrations and water temperature; and the maximum specific growth rate was simply proportional to water temperature. According to the relations found, a simple equation is presented for the estimation of phytoplankton growth in a given upwelling. Succession of species in the phytoplankton assemblage in upwelled water mass was also taken into consideration.     

螺旋藻培养与动力学模型

在内循环气升式光生物反应器中,就螺旋藻细胞在不同碳源培养其中的生长行以及藻细胞对光能和碳源的利用特性进行了初步研究,结果表明,向培养体系中通入气体流量1％的CO2,有助于提高经式培养的细胞终浓度和稳定培养体系的PH环境;改进的Lambert-Beer定律可较好地描述细胞浓度及光程对光衰减的综合影响,引入平均光强和平均比消光量概念,探讨了细胞比生长速率与它们之间的关系;藻液中总碳量随细胞浓度的上升呈指数关系减少,藻细胞对碳源的得率系数在批式 不同时期之间存在差异。图12参9     

Nutrient uptake kinetics and growth of zooxanthellae maintained in laboratory culture

Growth characteristics and nutrient uptake kinetics were determined for zooxanthellae (Gymnodinium microadriaticum) in laboratory culture. The maximum specific growth rate (_max) was 0.35 d^-1 at 27 °C, 12 hL:12 hD cycle, 45 E m^-2 s^-1. Anmmonium and nitrate uptake by G. microadriaticum in distinct growth phases exhibited Michaelis-Menten kinetics. Ammonium half-saturation constants (K_s) ranged from 0.4 to 2.0 M; those for nitrate ranged from 0.5 to 0.8 M. Ammonium maximum specific uptake rates (V_max) (0.75 to 1.74 d^-1) exceeded those for nitrate (0.14 to 0.39 d^-1) and were much greater than the maximum specific growth rate (0.35 d^-1), suggesting that ammonium is the more significant N source for cultured zooxanthellae. Ammonium and nitrate V_max values compare with those reported from freshly isolated zooxanthellae. Light enhanced ammonium and nitrate uptake; ammonium inhibited nitrate uptake which was not reported for freshly isolated zooxanthellae, suggesting that physiological differences exist between the two. Knowledge of growth and nutrient uptake kinetics for cultured zooxanthellae can provide insight into the mechanisms whereby nutrients are taken up in coral-zooxanthelae symbioses.Contribution No. 1515 from the University of Maryland Center for Environmental and Estuarine Studies, Chesapeake Biological Laboratory, Solomons, Maryland 20688-0038, USA     

Dynamics and physiology of saxitoxin production by the dinoflagellatesAlexandrium spp.

Toxin content (fmol cell^–1) and a suite of elemental and macromolecular variables were measured in batch cultures of the dinoflagellatesAlexandrium fundyense, A. tamarense andAlexandrium sp. from the southern New England region, USA. A different perspective was provided by semicontinuous cultures which revealed sustained, steady-state physiological adaptations by cells to N and P limitation. Two types of variability were investigated. In batch culture, changes in nutrient availability with time caused growth stage variability in toxin content, which often peaked in mid-exponential growth. A second type of variability that could be superimposed on growth stage differences is best exemplified by the high toxin content of cells grown at suboptimal temperatures. Calculations of the net rate of toxin production (R _tox ; fmol cell^–1 d^–1) for these different culture treatments and modes made it possible to separate the dynamics of toxin production from cell division. Over a wide range of growth rates, cells produced toxin at rates approximating those needed to replace losses to daughter cells during division. The exception to this direct proportionality was with P limitation, which was associated with a dramatic increase in the rate of toxin production as cells stopped dividing due to nutrient limitation in batch culture. Growth stage variability in batch culture thus reflects small imbalances (generally within a factor of two) between the specific rates of toxin production and cell division. N limitation and CO₂ depletion both affect pathways involved in toxin synthesis before those needed for cell division; P limitation does the opposite. The patterns of toxin accumulation were the same as for major cellular metabolites or elemental pools. The highest rates of toxin production appear to result from an increased availability of arginine (Arg) within the cell, due to either a lack of competition for this amino acid from pathways involved in cell division or to increased de novo synthesis. There were no significant changes in toxin content with either acclimated growth at elevated salinity, or with short term increases or decreases of salinity. These results demonstrate that toxin production is a complex process which, under some conditions, is closely coupled to growth rate; under other conditions, these processes are completely uncoupled. Explanations for the observed variability probably relate to pool sizes of important metabolites and to the differential response of key biochemical reactions to these pool sizes and to environmental conditions.     

作物地上部氨排放及对大气氮沉降的吸收

为研究作物地上部分氨排放以及对大气氮沉淀的吸收情况,以水稻(Oryza saliva L.)品种武运粳7号和小麦(Triticumaestivum L.)品种扬麦15为例.在盆栽条件下,利用~15N同位素示踪技术,采用探索性的研究方法,初步分析了水稻成熟期植株NH_3排放和小麦植株直接吸收的大气沉降氮.结果表明,土培的水稻品种武运粳7号地上部植株成熟期排放氨氮(NH_3-N)量约占当季总施氮(N)量的(0.50±0.21)%;收获后水稻植株不同部位~(15)N丰度值以根部最高,茎叶次之,籽粒最低,这与植株体内养分的运移顺序变化一致;贫化~(15)N小麦砂培试验测定的包括植株直接吸收在内的大气氮沉降数量为N(14.8±4.3)kg·hm~(-2),低于国外类似方法以其它作物作为研究对象的测定结果.     

Nutrient starvation effects on the allelochemical potency of Alexandrium tamarense (Dinophyceae)

Batch culture experiments were performed to investigate potential effects of nutrient starvation on the allelochemical potency of the toxic dinoflagellate Alexandrium tamarense. Triplicate cultures with reduced nitrate (−N) or phosphate (−P) seed were compared to nutrient-replete (+N+P) cultures. Total depletion of the dissolved inorganic limiting nutrient, reduced cell quotas, changed mass ratios of C/N/P and reduced cell yield clearly indicate that treatment cultures at stationary phase were starved by either N or P, whereas growth cessation of +N+P cultures was probably due to carbon limitation and/or a direct effect of high pH. Pulsed addition of the limiting nutrient allowed −N and −P cultures to resume growth. Lytic activity of A. tamarense as quantified by a Rhodomonas bioassay was generally high (EC₅₀ around 100 cells mL⁻¹) and was only slightly modulated by growth phase and/or nutrient starvation. Lytic activity per cell increased with time in both +N+P and −P cultures but not −N cultures. P-starved stationary-phase cells were slightly more lytic than +N+P cultures, but this difference may be due to increased cell size and/or accumulation of extracellular compounds. In conclusion, only slight changes but no general and major increase in lytic activity in response to nutrient starvation was observed.     

Carbon and nitrogen metabolism by Monochrysis lutheri: Measurement of growth-rate-dependent respiration rates

Dark respiration rates were measured and carbon-excretion rates calculated for a nitrate-limited population of the marine chrysophyte Monochrysis lutheri grown in continuous culture at 20°C on a 12 h light-12 h dark cycle of illumination and over a series of 4 growth rates. A significant (P<0.05) positive correlation was found between dark respiration rate and growth rate. From a simple linear fit to the data, the respiration rate at maximum growth rate was estimated to be roughly 10.5% of the maximum gross-carbon-production rate, and more than three times higher than the extrapolated respiration rate at zero net-growth rate. Carbon-excretion rates showed no significant correlation with growth rate, and averaged less than 5% of the maximum gross-carbon-production rate. Mean cell nitrogen to carbon ratios were correlated in a virtually linear manner (r=0.994) with growth rate, and at a given growth rate were consistently higher than nitrogen to carbon ratios for the same species grown on continuous light. A comparison of carbon and nitrogen quotas as a function of growth rate for M. lutheri and other species suggests that the increase of cellular nitrogen at high growth rates under nitrate-limited growth conditions may be associated with the storage of cellular protein or amino acids rather than the presence of an inorganic nitrogen reservoir. The maximum nitrate uptake rate per cell during the day changed very little over the range of growth rates studied, and was comparable to the maximum uptake rate found for cells grown on continuous light. However, the cell nitrogen quota increased steadily with growth rate, causing a reduction in the maximum specific-uptake rate of nitrate during the day at high growth rates. The dark nitrate-uptake capacity of the population was clearly exceeded by the supply rate at the two higher growth rates, leading to a buildup of nitrate during the night which amounted to as much as 21% of the particulate nitrogen in the growth chamber by morning.Hawaii Institute of Marine Biology Contribution No. 478.     

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading enrichment history

Effect of nitrogen on mixed culture PHA production was reconsidered. Enrichment history of PHA accumulating culture was discussed. Higher PHA content and biomass growth were achieved in presence of nitrogen. Enrichment strategy toward higher PHA accumulation was investigated. Microbial community succession in PHA accumulation phase was investigated. In most of the operating strategies for mixed microbial cultures polyhydroxyalkanoate (PHA) production, moderate organic loads and low nitrogen concentrations are used, however, the real waste streams contain variable concentrations of carbon and nitrogen. To evaluate the effect of enrichment history on PHA producer and production the various carbon and nitrogen levels were utilized during the accumulation phase. Different operating strategies were applied in three sequencing batch reactors (SBRs) subjected to aerobic dynamic feeding. The maximum PHA production of the enriched cultures under nutrient excess, limitation and starvation (Cmol/Nmol ratio of 8, 40 and ∞, respectively) was evaluated in batch assays. A higher PHA content and biomass growth were achieved in the nutrients presence in comparison to the nutrient starvation condition. The cultures from the SBR treated under short sludge retention time, high organic loading rate, short cycle length (SBR#3) and nutrient excess reached the maximum PHA content (54.9%) and biomass increase (38.9%). Under nutrient limitation, the negative biomass growth was observed under nutrient starvation because of the sampling loss. The succession of microbial communities in SBRs and batch assays was analyzed using terminal restriction fragment length polymorphism. The SBR#3 had the best overall PHA production performance considering its high PHA content and productivity in all nutrient content, it indicates that nitrogen has a substantial impact on PHA yield especially when high organic loading rate enrichment history is involved.