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排序方式: 共有105条查询结果,搜索用时 15 毫秒
1.
D. R. J. Grootjen R. G. J. M. van der Lans K. Ch. A. M. Luyben 《Biotechnology Techniques》1990,4(3):149-154
Summary In some fermentations micro-aerobic conditions are desirable. The controlled addition of trace amounts of oxygen may be achieved by bubble free oxygen supply using silicon membrane tube, operated in dead-end mode. The small oxygen uptake rate is accurately determined with this self-constructable device. 相似文献
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In Part I of this series,(1) we derived a model and made simulations for a multistage fluidized bed reactor (MFBR). It was concluded that the MFBR can be an attractive alternative for a fixed bed reactor when operated with a deactivating biocatalyst. In Part II of this series, the design of a laboratory-scale MFBR and its evaluation to investigate the practical feasibility of this reactor type, will be described. Experiments with a duration as long as 10 days were carried out successfully using immobilized glucose isomerase as a model reaction system. The results predicted by the model are in good agreement with the measured glucose concentration and biocatalyst activity gradients, indicating perfect mixing of the particles in the reactor compartments.The diameters of the biocatalyst particles used in the experiments showed a large spread, with the largest being 1.7 times the smallest. Therefore, an additional check was carried out, to make sure that the particles were not segregating according to size. Particles withdrawn from the reactor compartments were investigated using an image analyzer. Histograms of particle size distribution do not indicate segregation and it is concluded that the particles used have been mixed completely within the compartments. As a result, transport of biocatalyst is nearly plug flow. 相似文献
4.
1. The responsiveness of adenylate cyclase and enzyme secretin for secretin and the C-terminal octapeptide of pancreozymin has been investigated in particulate fractions of the pancreas of five different species. 2. The adenylate cyclase is sensitive to the C-terminal octapeptide of pancreozymin in all species investigated. 3. The enzyme is much more sensitive to secretin in rat and cat than in mouse and rabbit, whereas with guinea pig intermediate values are obtained. 4. The enzyme secretion is stimulated by secretin in pancreatic fragments of rat and cat, but not in those of mouse and rabbit. 5. These results suggest that in species where secretin stimulated enzyme secretion, it does so by stimulating the adenylate cyclase system. 相似文献
5.
W. J. Groot H. S. Soedjak P. B. Donck R. G. J. M. van der Lans K. Ch. A. M. Luyben J. M. K. Timmer 《Bioprocess and biosystems engineering》1990,5(5):203-216
Extraction can successfully be used for in-situ alcohol recovery in butanol fermentations to increase the substrate conversion. An advantage of extraction over other recovery methods may be the high capacity of the solvent and the high selectivity of the alcohol/water separation. Extraction, however, is a comprehensive operation, and the design of an extraction apparatus can be complex. The aim of this study is to assess the practical applicability of liquid-liquid extraction and membrane solvent extraction in butanol fermentations. In this view various aspects of extraction processes were investigated.Thirty-six chemicals were tested for the distribution coefficient for butanol, the selectivity of alcohol/water separation and the toxicity towards Clostridia. Convenient extractants were found in the group of esters with high molar mass.Liquid-liquid extraction was carried out in a stirred fermenter and a spray column. The formation of emulsions and the fouling of the solvent in a fermentation broth causes problems with the operation of this type of equipment. With membrane solvent extraction, in which the solvent is separated from the broth by a membrane, a dispersion-free extraction is possible, leading to an easy operation of the equipment. In this case the mass transfer in the membrane becomes important.With membrane solvent extraction the development of a process is emphasized in which the extraction characteristics of the solvent are combined with the property of silicone rubber membranes to separate butanol from water. In the case of apolar solvents with a high molar mass, the characteristics of the membrane process are determined completely by the solvent. In the case of polar solvents (e.g. ethylene glycol), the permselectivity of the membrane can profitably be used. This concept leads to a novel type of extraction process in which alcohol is extracted with a water-soluble solvent via a hydrophobic semipermeable membrane. This extraction process has been investigated for the recovery of butanol and ethanol from water. A major drawback in all processes with membrane solvent extraction was the permeation of part of the solvent to the aqueous phase.The extraction processes were coupled to batch, fed batch and continuous butanol fermentations to affirm the applicability of the recovery techniques in the actual process. In the batch and fed batch fermentations a three-fold increase in the substrate consumption could be achieved, in the continuous fermentation about 30% increase. 相似文献
6.
Plasmonics - This study shows development of highly sensitive and stable localized surface plasmon resonance (LSPR)-active U-bent glass and polymeric optical fiber (GOF and POF) sensor probes by a... 相似文献
7.
Hoeks FW Boon LA Studer F Wolff MO van der Schot F Vrabél P van der Lans RG Bujalski W Manelius A Blomsten G Hjorth S Prada G Luyben KCh Nienow AW 《Journal of industrial microbiology & biotechnology》2003,30(2):118-128
Foam disruption by agitation—the stirring as foam disruption (SAFD) technique—was scaled up to pilot and production scale
using Rushton turbines and an up-pumping hydrofoil impeller, the Scaba 3SHP1. The dominating mechanism behind SAFD—foam entrainment—was
also demonstrated at production scale. The mechanistic model for SAFD defines a fictitious liquid velocity generated by the
(upper) impeller near the dispersion surface, which is correlated with complete foam disruption. This model proved to be scalable,
thus enabling the model to be used for the design of SAFD applications. Axial upward pumping impellers appeared to be more
effective with respect to SAFD than Rushton turbines, as demonstrated by retrofitting a 12,000 l bioreactor, i.e. the triple
Rushton configuration was compared with a mixed impeller configuration from Scaba with a 20% lower ungassed power draw. The
retrofitted impeller configuration allowed 10% more broth without risking excessive foaming. In this way a substantial increase
in the volumetric productivity of the bioreactor was achieved. Design recommendations for the application of SAFD are given
in this paper. Using these recommendations for the design of a 30,000 l scale bioreactor, almost foamless Escherichia coli fermentations were realised.
Electronic Publication 相似文献
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W. J. Groot C. M. Sikkenk R. H. Waldram R. G. J. M. van der Lans K. Ch. A. M. Luyben 《Bioprocess and biosystems engineering》1992,8(1-2):39-47
The productivity of a fermentation is proportional to the biomass concentration. The productivity can therefore be increased by retention of the cells in the fermentor. In this study microfiltration was used for cell retention in a fermentation of glucose to ethanol by baker's yeast. Compared to a system without cell retention the productivity could be increased 12-fold to 55 kg/m3 h at a biomass concentration of 135 kg/m3. Maximal ethanol concentrations of 76 kg/m3 were obtained at conditions of growth. At zero growth conditions in the integrated system the ethanol concentration could be increased to about 115 kg/m3, and could be produced for at least 10 hours. The fermentation results in the integrated system could be described reasonably well with a mathematical model based on a different linear inhibition kinetics for growth and substrate consumption. 相似文献
10.
Dukka B KC 《BMC structural biology》2009,9(1):12-9