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M. J. van der Werf S. Hartmans W. J. J. van den Tweel 《Applied microbiology and biotechnology》1995,43(4):590-594
Pseudomonas pseudoalcaligenes can only form d-malate from maleate after incubation of the cells with a solvent or a detergent. The effect of the detergent Triton X-100 on d-malate production was studied in more detail. The longer the cells were incubated with Triton X-100, the higher was the d-malate production activity, until the maximal malease activity was reached. Incubation of P. pseudoalcaligenes cells with Triton X-100 also resulted in an increase in the protein concentration of the supernatant, indicating that cell lysis had occurred. The rate at which the d-malate production activity increased was dependent on the Triton X-100 concentration and on the cell density. Also the rate at which lysis occurred depended on the Triton X-100 concentration. 相似文献
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Isolation of 5-oxoprolinase from a prokaryote 总被引:1,自引:0,他引:1
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The new medium MDSS2N, free of any animal protein supports cell growth and production of various viruses 总被引:1,自引:0,他引:1
O.-W. Merten H. Kallel J.-C. Manuguerra M. Tardy-Panit R. Crainic F. Delpeyroux S. Van der Werf P. Perrin 《Cytotechnology》1999,30(1-3):191-201
The development of media free of serum and animal or human proteins is of utmost importance for increasing the safety of biologicals
produced for therapy and vaccination. In order to reduce the risk of contamination, we have modified the serum free medium
MDSS2, a very efficient serum free medium for the production of various biologicals including experimental vaccines using
different cell lines (Merten et al., 1994), by replacing the animal derived products by plant extracts. The new serum and
animal protein free medium (MDSS2N) can be efficiently used for biomass production of various cell lines. These cells grow
equally well or better in this new serum-free medium than in the old formulation (MDSS2):
• BHK-21/BRS cells, adapted to MDSS2N, showed an overall specific growth rate of 0.0197 h-1 (μ_max = 0.0510±0.0058 h-1), whereas
those cultivated in MDSS2 grew with an average specific growth rate of 0.0179 h-1 (μ_max = 0.0305±0.0177 h-1).
• Vero cells grew with an average specific growth rate of 0.0159 h-1 and 0.0153 h-1 in MDSS2 and MDSS2N, respectively. Very
similar growth rates were obtained in microcarrier cultures in stirred tank reactors: the specific growth rates were 0.0161
h-1 and 0.0166 h-1 for MDSS2 and MDSS2N cultures, respectively.
• For MDCK cells, when cultured on microcarriers in bioreactors, a higher average specific growth rate was observed in MDSS2N
than in MDSS2; values of 0.0248 h-1 and 0.0168 h-1, respectively, were obtained.
The capacity of MDSS2N to support the production of different viruses was equally evaluated and it could be established that
for certain viruses there are no or insignificant differences between MDSS2N and MDSS2 (influenza and polio virus), whereas,
the production of rabies virus is somewhat reduced in MDSS2N when compared to MDSS2. The use of MDSS2N for cell culture and
the production of various viruses is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Sensitivity Analysis of Environmental Process Modeling in a Life Cycle Context: A Case Study of Hemp Crop Production 下载免费PDF全文
Andrianandraina Anne Ventura Tristan Senga Kiessé Bogdan Cazacliu Rachida Idir Hayo M. G. van der Werf 《Journal of Industrial Ecology》2015,19(6):978-993
The aim of this article is to develop a methodological approach allowing to assess the influence of parameters of one or more elementary processes in the foreground system, on the outcomes of a life cycle assessment (LCA) study. From this perspective, the method must be able to: (1) include foreground process modeling in order to avoid the assumption of proportionality between inventory data and reference flows; (2) quantify influences of foreground processes’ parameters (and, possibly, interactions between parameters); and (3) identify trends (either increasing or decreasing) for each parameter on each indicator in order to determine the most favorable direction for parametric variation. These objectives can be reached by combining foreground system modeling, a set of two different sensitivity analysis methods (each one providing different and complementary information), and LCA. The proposed method is applied to a case study of hemp‐based insulation materials for buildings. The present study will focus on the agricultural stage as a foreground system and as a first step encompassing the entire life cycle. A set of technological recommendations were identified for hemp farmers in order to reduce the crop's environmental impacts (from –11% to –89% according to the considered impact category). One of the main limitations of the approach is the need for a detailed model of the foreground process. Further, the method is, at present, rather time‐consuming. However, it offers long‐term advantages given that the higher level of model detail adds robustness to the LCA results. 相似文献
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John Michael Hardman Wopke van der Werf Suzanne E. Blatt Jeffrey L. Franklin Richard Karsten Holger Teismann 《Experimental & applied acarology》2013,60(2):181-203
Successful biological control of mites is possible under various conditions, and identifying what are the requirements for robust control poses a challenge because interacting factors are involved. Process-based modeling can help to explore these interactions and identify under which conditions biological control is likely, and when not. Here, we present a process-based model for population interactions between the phytophagous mite, Tetranychus urticae, and its predator, Typhlodromus pyri, on apple trees. Temperature and leaf nitrogen concentration influence T. urticae rates of development and reproduction, while temperature and rate of ingestion of prey and pollen influence T. pyri rates of survival and reproduction. Predator and prey population dynamics are linked through a stage structured functional response model that accounts for spatial heterogeneity in population density throughout the trees. T. urticae biomass-days (BMD’s), which account for sizes of larvae, nymphs and adults, indicate level of mite-induced leaf damage. When BMD’s exceed 290 per leaf, there are economic losses. When BMD’s exceed 350 per leaf, T. urticae population growth is curbed and eventually the population decreases. Simulations were run to determine which conditions would lead to current year economic loss and increased risk of loss in the following year, i.e. where more T. urticae than T. pyri are present at the end of September. Risk was high with one or more of the following initial conditions: a high prey: predator ratio (10:1 or more); a low to intermediate (0.04–0.2 T. urticae per leaf) initial density; T. urticae with a higher initial proportion of adult females than T. pyri; and a delayed first detection of mites, whether in late July, or sometimes in late June, but not in early June. Warm summer weather, higher leaf nitrogen and T. urticae immigration into trees were also risk factors. Causes for these patterns based on biological characteristics of T. urticae and T. pyri are discussed, as are counter measures which can be taken to reduce risk. 相似文献
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P. Grijpma J. J. M. Belde D. C. van der Werf 《Entomologia Experimentalis et Applicata》1987,45(3):219-255
Artificial diets were reviewed and two tested. The highest level of survival to the adult stage (72%) was obtained on a modified diet of Odell & Rollinson (1966). Rearing required 61 days for males and 70 days for females. Wing deformation occurred in 16% of the adults. The sex ratio ( : ) was 0.80. Average pupal weight was 281 mg for males and 368 mg for females. Females averaged 102 eggs (range 80–125 eggs). Neonates from field-collected egg masses started hatching on 6 December; frost was not necessary for hatching. Hatching could be postponed until at least 10 November of the following year by storing egg masses at-2°C. L. monacha can be maintained continuously in the laboratory.
Zusammenfassung Eine Massenvermehrung der Nonne, Lymantria monacha (L.), trat in 1984 auf 500 ha Pinus sylvestris bei Budelerbergen (S.O. der Niederlande) auf und betraf 1985 eine Fläche von 2800 ha. Obwohl die Vermehrung durch eine Luftapplikation mit Dimilin 25 bekämpft werden konnte, wurden Untersuchungen begonnen zur Entwicklung von für die Umwelt sicheren Bekämpfungsmethoden, besonders die Anwendung von Virosen. Das Ziel bestand in der Virusproduktion in künstlichen Raupenzuchten. Die Nonne wurde bisher mit verschiedenen für andere Insektenarten oder speziell für diesen Zweck entwickelten künstlichen Nährböden gezüchtet. Da die Zusammensetzung dieser Nährböden und die Zuchtmethoden nicht veröffentlicht waren und da wenige Details über die Raupenentwicklung vorlagen, wurden modifizierten Nährböden von McMorran sowie von Odell & Rollinson für die Massenzucht der Nonne geprüft.相似文献
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