组正交超饱和设计在发酵罐手工清洗方法开发中的应用

目的 开发一种适用于发酵罐手工清洗方法.方法 采用组正交超饱和设计方法(15个因素2个水平),试验因素包括9个实际影响发酵罐清洗因素和6个假因素;评价指标为发酵罐清洗后淋洗水电导率与总有机碳(total organic carbon,TOC)含量;通过标准最小二乘法拟合试验结果获得较优清洗条件,从而建立发酵罐手工清洗方...     

On the determination of optimal thermal enclosures

The paper presents a method for a quantitative study of the influence of the diurnal air temperature cycle, the incidence of solar energy on exposed surfaces and transmission through glass areas, the longwave radiation exchange with the surroundings, and the energy exchange resulting from natural ventilation. The thermal response of a room in a typical concrete office building with glass areas facing south in the northern hemisphere is treated in detail by means of a digital computer program sufficiently general to handle a large variety of problems. For the first time the influence of programmed natural ventilation can be determined in advance. The design of optimal thermal enclosures can be achieved through the technique of exhaustive analysis using methods described in this paper.

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Zusammenfassung Es wird über eine Methode für die quantitative Untersuchung der Einflüsse des tÄglichen Gangs der Lufttemperatur, der Sonnenenergieaufnahme an den bestrahlten OberflÄchen und durch die Glasfenster, des langwelligen Strahlungsaustausches mit der Umgebung und des Energieaustausches durch die natürliche Ventilation berichtet. Das thermische Verhalten eines Raumes in einem typischen Beton-Bürohaus mit südlich orientierten GlasfensterflÄchen auf der nördlichen Halbkugel ist ausführlich durch das digital Rechenmaschinenprogramm untersucht worden, das genügt, um eine ausführliche Anzahl verschiedener Probleme zu behandeln. Zum erstenmal kann der Einfluss der programmierten natürlichen Ventilation vorausbestimmt werden. Der Entwurf eines thermisch optimalen eingeschlossenen Raumes kann durch die hier beschriebenen erschöpfenden Analysen gegeben werden.

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Resume Ce mémoire présente une méthode qui permet d'étudier quantitativement l'influence des facteurs suivants: Le cycle diurne de la température de l'air, l'angle d'incidence de l'énergie solaire sur les parois qui y sont exposées, la transmission de la chaleur à travers des surfaces de verre, les échanges d'énergie avec le milieu ambiant par rayonnement calorifique sur ondes longues et, enfin, les échanges d'énergie par ventilation naturelle. On étudie en détail les conditions thermiques d'une chambre située dans un bâtiment de béton pourvu de parois de verre exposées au sud, le tout étant situé à une latitude boréale. Cette étude est effectuée au moyen d'un programme d'ordinateur digital suffisament général pour s'appliquer à la solution de nombreux problèmes de transmission de chaleur. On montre, pour la première fois, que l'on peut déterminer d'avance l'influence d'une ventilation naturelle programmée. L'établissement de l'optimum thermique des intérieurs peut se faire par une analyse très poussée, c'est à dire à l'aide des méthodes décrites dans cette étude.

     

Ethanol fermentation characteristics of Thermoanaerobacter ethanolicus

Thermoanaerobacter ethanolicus is an extreme thermophilic non-spore forming ethanol-producing anaerobic bacterium. Minimum nutrient requirements and optimum growth conditions have been established. An optimum yeast extract-glucose ratio for ethanol yield has also been determined. Initial medium pH, optimally 7.5–8.0, significantly affected the amount of ethanol formed. Maximum specific growth rate was found to be 0.22 h^?1at pH 7.5 and 69°C. Ethanol concentration up to 11 g l^?1at pH 7.5 and 69°C was used to characterize ethanol inhibition. The growth kinetics of T. ethanolicus were characterized in terms of environmental parameters. Substrate utilization, ethanol formation and inhibition by both sugar and ethanol were also quantified.     

The fermentation of L-sorbose by Gluconobacter melanogenus. I. General characteristics of the fermentation

Growing cultures, washed cells, and cell-free preparations of Gluconobacter melanogecnus IFO 3293 converted L -sorbose to 2-keto-L -gulonic acid, to D -sorbitol (which was metabolized further) and to 5-keto-D -fructose.     

Continuous determination of protease during the fermentation using the autoanalyzer adm 300

A method for automatic determination of proteolytic activity during fermentation is described. Therefore the autoanalyzer ADM 300 of the PRUEFGERAETEWERK MEDINGEN F.R.G. is connected to a fermenter. After filtration of the biomass, the culture filtrate is diluted and then incubated with casein solution. (0.75%, pH 8.0, 55°C) low moleculare cleavage products are separated from higher molecular ones by dialysis. The absorbence is measured at 600 nm after addition of alkaline copper tartrate and FOLIN solution. By use of different dilution rates, a range of 0–32 units ml^?1 may be measured. The coefficient of variation is 5.5.     

Micromethod for the quantitative determination of succinic acid in the fermentation media

Summary A rapid and accurate method is described for the determination of succinic acid allowing direct application of the fermentation broth filtrate to TLC plate. Subsequent chromatographic separation on silica gel thin-layer and detection of succinic acid by a copper salt reagent, permits quantitative densitometric evaluation of succinic acid in the concentration range from 10 to 40 g. The quantitative analyses are reproducible and the assay has a coefficient of variation of 3.2%.     

Turnover characteristics in continuous l-lysine fermentation

The turnover characteristics of a microbial bioreactor were comparatively investigated as a closed (batch) and a continuous stirred tank reactor (CSTR) open system, using a 2-l fermentor. Corynebacterium glutamicum (ATCC 21544) was chosen as the microorganism since it has the ability to produce l-lysine. Parameters measured were l-lysine production rates, glucose consumption rates and biomass production rates as a function of dilution rate, bioreactor volume and biomass concentration. The modes of microbial cell behaviour under steady-state and transition-state conditions were examined. Investigations on scaling properties of the CSTR system were also aimed at comparing scaling or allometry of metabolic rates in organisms that are also open energy dissipative systems.This investigation was first presented at the 10th Dechema-Jahrestagung der Biotechnologen, 1–3 June 1992, Karlsruhe, Germany     

Dynamic measurement of the volumetric oxygen transfer coefficient in fermentation systems

A rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient, k_La, in fermentation systems. The method consists of tracing the dissolved O₂ concentration of the fermentation broth during a short interruption of the aeration. The O₂ concentration trace thus obtained can be analyzed to determine the values of k_La. Additional experiments on prolonged O₂ starvation, carried out to find the limitation of the technique, suggest that O₂ uptake rate will vary if a prolonged (2–10 min.) O₂ starvation occurs.     

Dynamic analysis of lactic acid fermentation in membrane bioreactor

In this paper, a mathematical model for the lactic acid fermentation in membrane bioreactor is investigated. This novel theoretical framework could result in an objective criterion on how to control the substrate concentration in order to keep a sustainable and steady output of lactic acid. Firstly, continuous input substrate is taken. The existence and local stability of two equilibria are studied. According to Poincaré-Bendixson Theorem, we obtain the conditions for the globally asymptotical stability of the equilibrium. Secondly, impulsive input substrate is also considered. Using Floquet's theorem and small-amplitude perturbation, we obtain the biomass-free periodic solution is locally stable if some conditions are satisfied. In a certain limiting case, it is shown that a nontrivial periodic solution emerges via a supercritical bifurcation. Finally, our findings are confirmed by means of numerical simulations.     

Dynamic process control versus steady-;state fermentation

Process control strategies, e.g. the steady-;state fermation, which do not consider the cell-;state distribution of cell populations, cause a decrease of yield coefficient connected to an increase of heat-;production coefficient. Contrary to this, the dynamic process control adapts the carbon-;substrate supply to the different repetitive cell-;population states during fermentation. In order to recognize the different states, the cell population is synchronized. The optimum period ofchanging carbon-;substrate supply was found to be dependent on the cell-;doubling time. Dynamic process control causes a higher yield coefficient as well as a lower heat-;production coefficient compared to the steady-;state fermentation.     

Effect of monensin on fermentation characteristics of the artificial rumen.

Addition of monensin (Rumensin, Eli Lilly and Co.) to an artificial rumen immediately depressed the digestion of roughage and of roughage/concentrate (50:50) feeds. Methane and propionate production were affected only with the roughage/concentrate feed.     

Rapid determination of the thermal nociceptive threshold in diabetic rats

Painful diabetic neuropathy (PDN) is characterized by hyperalgesia i.e., increased sensitivity to noxious stimulus, and allodynia i.e., hypersensitivity to normally innocuous stimuli¹. Hyperalgesia and allodynia have been studied in many different rodent models of diabetes mellitus². However, as stated by Bölcskei et al, determination of "pain" in animal models is challenging due to its subjective nature³. Moreover, the traditional methods used to determine behavioral responses to noxious thermal stimuli usually lack reproducibility and pharmacological sensitivity³. For instance, by using the hot-plate method of Ankier⁴, flinch, withdrawal and/or licking of either hind- and/or fore-paws is quantified as reflex latencies at constant high thermal stimuli (52-55 °C). However, animals that are hyperalgesic to thermal stimulus do not reproducibly show differences in reflex latencies using those supra-threshold temperatures^3,5. As the recently described method of Bölcskei et al.⁶, the procedures described here allows for the rapid, sensitive and reproducible determination of thermal nociceptive thresholds (TNTs) in mice and rats. The method uses slowly increasing thermal stimulus applied mostly to the skin of mouse/rat plantar surface. The method is particularly sensitive to study anti-nociception during hyperalgesic states such as PDN. The procedures described bellow are based on the ones published in detail by Almási et al⁵ and Bölcskei et al³. The procedures described here have been approved the Laboratory Animal Care and Use Committee (LACUC), Wright State University.     

Dynamic characteristics of transient responses

Transient responses of signaling molecules are seen in a wide variety of cellular processes that are mediated by distinct molecular mechanisms. Although transient responses might intuitively be thought to depend on the absolute concentration of growth factors or the intensity of stimulation, we here introduce that some transient responses are prompted by temporal rate of increase of stimulation, rather than intensity of stimulation, by three independent mechanisms. These include the Ras system with fast activation and slow inactivation, the ERK-dependent negative feedback loop system, and the receptor degradation system, all of which can be commonly seen in various signaling networks. In addition, we show the distinct transient and steady state characteristics of these systems.     

Dynamic modeling of lactic acid fermentation metabolism with Lactococcus lactis

A dynamic model of lactic acid fermentation using Lactococcus lactis was constructed, and a metabolic flux analysis (MFA) and metabolic control analysis (MCA) were performed to reveal an intensive metabolic understanding of lactic acid bacteria (LAB). The parameter estimation was conducted with COPASI software to construct a more accurate metabolic model. The experimental data used in the parameter estimation were obtained from an LC-MS/ MS analysis and time-course simulation study. The MFA results were a reasonable explanation of the experimental data. Through the parameter estimation, the metabolic system of lactic acid bacteria can be thoroughly understood through comparisons with the original parameters. The coefficients derived from the MCA indicated that the reaction rate of L-lactate dehydrogenase was activated by fructose 1,6-bisphosphate and pyruvate, and pyruvate appeared to be a stronger activator of L-lactate dehydrogenase than fructose 1,6-bisphosphate. Additionally, pyruvate acted as an inhibitor to pyruvate kinase and the phosphotransferase system. Glucose 6-phosphate and phosphoenolpyruvate showed activation effects on pyruvate kinase. Hexose transporter was the strongest effector on the flux through L-lactate dehydrogenase. The concentration control coefficient (CCC) showed similar results to the flux control coefficient (FCC).     

Energy supply of the okapi in captivity: fermentation characteristics of feedstuffs

A variety of feeds are used in the nutrition of browsing ruminants. During digestion trials on okapis, feedstuffs of different facilities were sampled and the Hohenheim gas test was used as in vitro fermentation method to quantify their fermentative behavior. Forty‐six feeds were analyzed (7, fruit and vegetable; 11, energy concentrates and pelleted compounds; 13, forage; 9, browse leaf; 6, small and large twig samples). Gas production of these samples was recorded after 2, 4, 6, 8, 10, 12, and 24 hr of fermentation. Browse leaf samples were additionally analyzed with a tannin‐binding agent (polyethylene‐glycol) to assess limiting effects of condensed tannins. Metabolizable energy (ME) was estimated from 24 hr gas production according to standard regressions. Vegetables and particularly fruits were found to yield very high gas productions during the first 2 hr of fermentation, whereas unmolassed beet pulp was found to have a more even distribution of gas production/energy release over total fermentation time. Feeds like rolled oats or bread were evaluated to yield very high energy contents of >14 MJ ME/kg dry matter (DM). Alfalfa (Medicago sativa) hay had a comparable fermentation pattern to fresh browse samples, characterized by a high fermentation rate. In conclusion, energy‐rich constituents for captive ruminant diets should not include larger amounts of vegetables and especially fruits, due to their very fast fermentation during the initial phase of fermentation and the connected risk of rumen acidosis. Energy‐concentrates like beet pulp (unmolassed) showed moderate fermentation characteristics and energy content and are well suited as a component of zoo ruminant diets. Energy‐concentrates with very high energy densities (>13 MJ ME/kg DM) like bread or rolled oats are not suitable for a diet that is intended to promote long feeding times. Various aspects are involved in the decision for appropriate forage for browsing ruminants; based on fermentation pattern, alfalfa hay seems to be a reasonable substitute for browse leaves. Zoo Biol 0:1–16, 2006. © 2006 Wiley‐Liss, Inc.