基于遗传算法的麦角固醇分批发酵动力学参数估算

把遗传算法应用于求解麦角固醇分批发酵动力学模型参数,能进一步提高麦角固醇分批发酵过程状态变量的计算值与实验值的吻合程序,在计算机上对动力学模型进行了拟合,模拟值与实验值对比显示,该动力学模型能很好地反映麦角固醇分批发酵过程。     

麦角固醇高产菌株的构建及其培养优化条件的研究

通过初筛、单倍体分离、诱变及酵母菌种间原生质体融合技术构建了2株麦角固醇产量明显提高的优良菌株YEF-21和YEF-29。并对YEF-21的培养优化条件进行了研究。结果表明在优化的实验条件下YEF-21的生物量及麦角固醇含量的综合值分别为原始亲株YE227和YE180的1.54和1.55倍。经遗传稳定性分析,没有发现标记基因的分离现象,从而证明获得的融合菌株是遗传稳定的,是具有一定实际应用价值的麦角固醇高产菌株。     

用酵母生产麦角固醇发酵工艺的研究

研究了培养基中氮源、盐、温度、ｐＨ对酵母合成麦角固醇的影响。当选择复合氮源,蔗糖浓度为１０％～１２％,温度为３０℃,ｐＨ为５．５时,麦角固醇合成量相对于初始培养基提高了３倍。在２Ｌ发酵罐中探讨了蔗糖浓度、通气量对麦角固醇合成的影响,结果表明,高浓度蔗糖及大通气量对麦角固醇合成有一定抑制作用。通过流加蔗糖可显著地提高酵母麦角固醇合成量。     

Rhizopus delemar菌固态发酵生物量测定及其脂肪酶合成特征

研究了Rhizopus delemar菌固态发酵曲中麦角固醇的提取及其高效液相色谱（HPLC）测定方法。结果表明,固态曲中麦角固醇分离提取以1：25（w/v)的丙酮回流浸提2.0h为最佳,HPLC测定麦角固醇的条件为：HypersilC-8柱。甲醇/水（85/15,v/v)为流动相,流速为1.0mL/min,紫外检测波长为282nm。柱温为30℃。依据HPLC的分析测定,确定了麦角固醇与菌丝体间的定量关系,并以此为基础。测定了Rhizopus delemar菌固态发酵过程中的生物量变化。得到了生长曲线,发现当发酵培养至60h时固态曲中的生物量达到最大值为0.18g菌丝体/g干曲,而该菌所合成的脂肪酶的活力在48h达到最大值。     

真菌生物量指示剂麦角固醇的分离及测定方法*

麦角固醇作为真菌细胞膜的重要组成成分,结构稳定,可作为真菌生长的指示物质。综述了表征真菌生物量的麦角固醇的分离及测定方法,其中麦角固醇的萃取方法有传统的皂化回流法、快速物理萃取、超声波萃取、超临界流体萃取等,测定方法有高效液相色谱法、气相色谱-质谱法、液相色谱-质谱法、薄层色谱法等。并对这些方法的应用及在堆肥过程中运用麦角固醇估计真菌生物量的可行性进行了展望。     

麦角固醇产生菌Torullopsis famata优化发酵条件的研究

从12株产麦角固醇的酶母菌株中,筛选出一株麦角固醇产量较高的酵母菌（无名球拟酵母Torullopsis famata）,并对其产麦角固醇的条件进行了研究,结果表明：麦角固醇发酵的最佳条件为以蔗糖及复合氨源（黄豆粉＋NaNO3）为C、N源,温度28℃,pH5.5,装量250ml三角瓶装20ml,时间96h。麦角固醇的含量可达细胞干重的1.80%,平均产量可达74mg/100ml。     

影响酵母细胞麦角固醇的发酵控制参数的分析

研究了麦角固醇发酵过程中的参数。比较了溶氧、OUR、Ph和残糖浓度与酿酒酵母的生物量和麦角固醇含量的关系 ,并研究了这些参数之间的内在联系。研究表明 ,溶氧能比较准确地反映酵母的生长状况 ,是发酵过程中的一个较好的控制参数。将溶氧控制在 12 %左右能有效提高单位体积发酵液中的麦角固醇的产量。     

麦角固醇高产菌的选育

采用一种改进的测定麦角固醇的方法对167株不同种属的醇母菌细胞的麦角固醇含量进行了分析,从中获得两株麦角固醇含量比生产菌高2—3倍的菌株。研究了培养条件等对细胞麦角固醇含量及细胞生物量的影响。     

微生物麦角固醇的研究进展

麦角固醇是真菌细胞膜的重要组成成分,它在确保膜结构的完整性、与膜结合酶的活性、膜的流动性、细胞活力以及物质运输等方面起着重要作用。麦角固醇生物合成途径中的几个关键环节还是抗真菌药物的作用靶位,对其生物合成的研究将为抗真菌药物的筛选及其作用机制的研究提供重要的理论基础川。麦角固醇经UV照射可转化为维生素VDZ,VDZ是一种重要的药品．自从Taret首次从麦角中分离得到麦角固醇以来,随后便开展了对其来源、性质、分离、测定、高产株的选育及其发酵条件等的研究［‘－‘］。近年来一些研究者对麦角固醇生物合成途径进行…     

真菌生物量指示剂麦角固醇的分离及测定方法

麦角固醇作为真菌细胞膜的重要组成成分,结构稳定,可作为真菌生长的指示物质。综述了表征真菌生物量的麦角固醇的分离及测定方法,其中麦角固醇的萃取方法有传统的皂化回流法、快速物理萃取、超声波萃取、超临界流体萃取等,测定方法有高效液相色谱法、气相色谱-质谱法、液相色谱-质谱法、薄层色谱法等。并对这些方法的应用及在堆肥过程中运用麦角固醇估计真菌生物量的可行性进行了展望。     

Production and consumption of nitric oxide by denitrifying bacteria under anaerobic and aerobic conditions

Abstract: Pseudomonas aeruginosa, P. stutzeri and Azospirillum brasilense showed highest NO production rates and NO consumption rate constants when anaerobically grown cells were tested under anaerobic conditions. Aerobic assay conditions resulted in 20–75-fold lower NO production rates. NO consumption rate constants, however, decreased by less than a factor of four. NO consumption activity was observed even in aerobically grown P. aeruginosa , provided the assay was done under anaerobic conditions. Obviously, NO consumption was less O₂-sensitive than NO production so that compensation between production and consumption occurred at lower NO mixing ratios under aerobic than under anaerobic conditions.     

三种典型赤潮藻产生与消耗二甲基硫化物的速率估算

采用抑制剂加入法估算了中肋骨条藻、棕囊藻和东海原甲藻在不同生长期内二甲基硫化物的产生与消耗速率.结果表明:颗粒态二甲基巯基丙酸(DMSPp)和颗粒态二甲亚砜(DMSOp)在3种藻类的不同生长期内均为净消耗,溶解态二甲基巯基丙酸(DMSPd)和溶解态二甲亚砜(DMSOd)的含量受藻类产生与细菌病毒消耗控制,在藻类不同生长期内存在不同的产生与消耗速率,而二甲基硫(DMS)在3种藻不同生长期内均为净产生.同一种藻在不同生长期内以及不同藻在相同生长期内二甲基硫化物的产生与消耗速率均存在较大差异,表明藻类的生理状态和种间差异均对二甲基硫化物的产生与消耗速率产生影响.     

Ecosystem Subsidies to Swedish Food Consumption from 1962 to 1994

Analysis of food consumption and agricultural production trends in Sweden has focused on domestic food production levels and yields, overlooking human dependence on ecosystem support. We estimate the ecosystem areas appropriated (ArEAs) for agricultural production (crop and animal feed production and grazing in arable land and marine production for fishmeal used in animal feed) to satisfy Swedish food consumption needs from 1962 to 1994. The total agroecosystem areas worldwide supporting Swedish food consumption (that is, domestic production less exports plus imports) have declined by almost one-third since the 1960s as a result of consumption changes and agricultural intensification. By 1994, Swedish consumption of domestic food crops was halved and consumers relied on agricultural areas outside Sweden to satisfy more than a third (35%) of food consumption needs. Surprisingly, 74% of manufactured animal feed ArEAs were from imported inputs. Moreover, marine ArEAs equal to 12% of the total appropriated areas were needed to support fishmeal usage in animal feed. The results show that domestic agricultural areas do not support Swedish food consumption and that the bulk of manufactured feed used in animal products’ production in Sweden is supplied by ecosystems of other nations. These are hidden subsidies of nature, not explicit in Swedish national agricultural policy. Sweden must recognize its high level of dependence on the capacity of ecosystems of other nations to supply its food needs. Ignorance of ecosystem support may increase vulnerability.     

乳酸链球菌肽发酵动力学的研究

提出了在恒定不同pH的发酵条件下,乳酸链球菌SM526的菌体生长、底物消耗、乳酸及Nisin产生的动力学模型。菌体生长、乳酸及Nisin产生用逻辑方程描述,而底物消耗是菌体生长和乳酸产生速率的函数。模型表明,乳酸链球菌SM526菌体生长和乳酸产生的最佳pH为7．0,而Nisin产生的最佳pH却为6．5。     

Heat Production by the Denitrifying Bacterium Pseudomonas fluorescens and the Dissimilatory Ammonium-Producing Bacterium Pseudomonas putrefaciens during Anaerobic Growth with Nitrate as the Electron Acceptor

The heat production rate and the simultaneous nitrate consumption and production and consumption of nitrite and nitrous oxide were monitored during the anaerobic growth of two types of dissimilatory nitrate reducers. Pseudomonas fluorescens, a denitrifier, consumed nitrate and accumulated small amounts of nitrite or nitrous oxide. The heat production rate increased steadily during the course of nitrate consumption and decreased rapidly concomitant with the depletion of the electron acceptors. A mean experimental enthalpy change value of −800 kJ/mol of nitrate and a mean growth yield value of 33 g (dry weight)/mol of nitrate consumed were obtained for different concentrations of nitrate. For Pseudomonas putrefaciens, a dissimilatory ammonium producer, the nitrate consumption resulted in an accumulation of nitrite and nitrous oxide. Nitrite consumption commenced after depletion of the nitrate; consequently, two phases were noted in the heat production rate curve during growth. A mean experimental enthalpy change value of −810 kJ/mol of nitrate was obtained for different concentrations of nitrate.     

Thermogenesis of white adipocytes: a novel method allowing long-term microcalorimetric investigations

A microcalorimetric method was developed to facilitate long-term assessment of energy balance in isolated fat cells. White rat adipocytes were primary cultured in glass ampoules with a matrix of agar-gel. Heat production was measured continuously over 3 days with an LKB BioActivityMonitor. In order to assist interpretation of the microcalorimetric measurements, glucose consumption and lactate and pyruvate production were determined in parallel cultures. Heat production, glucose consumption and lactate production were in an apparent steady state throughout the study whether employing aerobic (94 pW, 0.50 and 0.44 pmol/cell. h, respectively) or partial anaerobic experimental conditions (39 pW, 0.41 and 0.57 pmol/cell.h, respectively). However, oxygen availability influenced the apparent heat production and glucose and lactate metabolism. With partial anaerobiosis a 59% lower heat production, an 18% lower glucose consumption and a 30% higher lactate production than by employing aerobic experimental conditions were observed.     

Characteristics of CHO-K1 cell culture producing two types of recombinant soluble thrombomodulin

Recombinant CHO-K1 cells, expressing human soluble thrombomodulin, were cultured in a serum-free medium and characteristics of the culture associated with glucose and lactate were investigated. In 3 L fermentor (3LFM) cultures, the cell density was found to have a proportional relationship with the volumetric glucose consumption rate, and the specific glucose consumption rates were constant at about 0.2 mg/(10⁶ cells·d) despite many differences in the culture conditions. Thus, it was concluded that the glucose consumption rate is little influenced by the condition of the cells or the culture conditions, and that the cell density can be estimated by the glucose consumption rate calculated from glucose measurement. Two types of thrombomodulin (rsTMα and rsTMβ) were produced, in which rsTMβ possesses chondroitin-4-sulfate and has greater anticoagulant activities than rsTMα. Therefore, it is important to investigate the rsTMα and rsTMβ production properties, and to determine the optimal culture conditions for high rsTMβ production. The most important factor to increase the production of rsTMβ relative to rsTMα (the β/α ratio) was effective aeration. Moreover, a lower ratio of lactate production/glucose consumption (the L/G ratio) with sufficient oxygen, high glucose concentration, and a longer medium exchange interval contributed to a higher specific rsTMβ production rate. Since there was a linear relationship between the production rate of each type of rsTM and the overall rsTM production rate per liter, it is expected that the rsTMα and rsTMβ production rates may be able to be estimated from the overall rate and the rsTMβ production increased by increasing the overall rsTM production with a lower L/G ratio.     

Metabolic activities of Listeria monocytogenes in the presence of sodium propionate, acetate, lactate and citrate

The effects of sodium propionate, acetate, lactate and citrate on cell proliferation, glucose and oxygen consumption, and ATP production in Listeria monocytogenes were investigated in growing and resting cells. Media pH was 6.7-6.8. Growth inhibition increased while glucose consumption continued in the presence of ≥ 1% propionate, ≥ 3% acetate and ≥ 5% lactate in broth during incubation at 35°C, indicating that glucose consumption was uncoupled from cell proliferation. Acetate and propionate were the most effective antilisterials, whereas citrate (5%) was only slightly inhibitory. Of the four salts, only lactate supported growth, oxygen consumption and ATP production. While concentrations of 1 and 5% propionate, acetate and citrate did not have an effect on oxygen consumption, they inhibited ATP production. ATP production in the presence of the four salts was consistently lower at pH 6.0 than at neutral pH. Lactate served as an alternative energy source for L. monocytogenes in the absence of glucose but became toxic to the organism in the presence of the carbohydrate.     

Trends in greenhouse gas emissions from consumption and production of animal food products – implications for long-term climate targets

To analyse trends in greenhouse gas (GHG) emissions from production and consumption of animal products in Sweden, life cycle emissions were calculated for the average production of pork, chicken meat, beef, dairy and eggs in 1990 and 2005. The calculated average emissions were used together with food consumption statistics and literature data on imported products to estimate trends in per capita emissions from animal food consumption. Total life cycle emissions from the Swedish livestock production were around 8.5 Mt carbon dioxide equivalents (CO₂e) in 1990 and emissions decreased to 7.3 Mt CO₂e in 2005 (14% reduction). Around two-thirds of the emission cut was explained by more efficient production (less GHG emission per product unit) and one-third was due to a reduced animal production. The average GHG emissions per product unit until the farm-gate were reduced by 20% for dairy, 15% for pork and 23% for chicken meat, unchanged for eggs and increased by 10% for beef. A larger share of the average beef was produced from suckler cows in cow–calf systems in 2005 due to the decreasing dairy cow herd, which explains the increased emissions for the average beef in 2005. The overall emission cuts from the livestock sector were a result of several measures taken in farm production, for example increased milk yield per cow, lowered use of synthetic nitrogen fertilisers in grasslands, reduced losses of ammonia from manure and a switch to biofuels for heating in chicken houses. In contrast to production, total GHG emissions from the Swedish consumption of animal products increased by around 22% between 1990 and 2005. This was explained by strong growth in meat consumption based mainly on imports, where growth in beef consumption especially was responsible for most emission increase over the 15-year period. Swedish GHG emissions caused by consumption of animal products reached around 1.1 t CO₂e per capita in 2005. The emission cuts necessary for meeting a global temperature-increase target of 2° might imply a severe constraint on the long-term global consumption of animal food. Due to the relatively limited potential for reducing food-related emissions by higher productivity and technological means, structural changes in food consumption towards less emission-intensive food might be required for meeting the 2° target.     

Effect of monovalent cations on glutamate metabolism in rat brain]

Glutamate oxidation in vitro via deamination and transamination during gramicidin C-induced transport of K+ and Na+ in rat nervous tissue mitochondria was studied. An increase in ammonium production, i.e. in glutamate oxidation due to deamination, was shown to occur with maximal increase of oxygen consumption in the presence of cations. It was found that 1.5 mM Na+ activate oxygen consumption by 15% and accelerate ammonium production from glutamate (by 17%). No changes in aspartate production were observed. 15 mM K+ increase oxygen consumption by 29% and ammonium production by 11% during a decrease in aspartate production as compared to glutamate oxidation in the presence of a lower (10 mM) concentration of K+ in the samples.