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1.
Synthesis of poly(3-hydroxyalkanoates) by mutant and recombinant Pseudomonas strains 总被引:1,自引:0,他引:1
Gjalt W. Huisman Eric Wonink Gertjan de Koning Hans Preusting Bernard Witholt 《Applied microbiology and biotechnology》1992,38(1):1-5
We have studied the accumulation kinetics and physical characteristics of the poly(3-hydroxyalkanoates) (PHAs) formed by several Pseudomonas strains, mutants and recombinants. Although PHA synthesis generally begins only after an essential nutrient such as N, P, S or Mg becomes limiting, we have identified at least one strain (P. putida KT2442) that begins producing PHA during the exponential growth phase. This PHA is chemically and physically identical to that produced by P. oleovorans GPol, the strain in which we first identified PHA. Analysis of the PHA formed by a mutant strain defective in PHA degradation (P. oleovorans GPo500) revealed that the molecular mass (Mw), the monomer composition and thermal characteristics were similar to that of the PHA of the wild-type parent strain P. oleovorans GPo1. The pha locus of P. oleovorans encodes enzymes that are involved in PHA biosynthesis and degradation. It has been subcloned to study the two PHA polymerases separately in a PHA– mutant (GPp104) derived from P. putida KT2442. The recombinant strains accumulated lower PHA levels than the wild-type strains, and the Mw of these polymers were lower than those produced by the wild-type P. oleovorans and parent strain. The monomer composition of the two PHAs formed by the two PHA polymerases differed, indicating that the PHA polymerases have different substrate specificities for the incorporation of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomers into PHA. Despite these differences, the PHAs formed were essentially indistinguishable from wild-type PHAs with respect to their thermal characteristics.Correspondence to: B. Witholt 相似文献
2.
Bruno Notarnicola Gjalt Huppes Nico W. van den Berg 《The International Journal of Life Cycle Assessment》1998,3(5):289-300
LCA aims to help direct decisions in an environmentally sustainable direction. It indicates the environmental effects of choices
and evaluates these against this background. Approaches to evaluation in LCA differ substantially, related to the way of modelling
environmental effects and to the way these effects are combined into an overall judgement on alternative options. Several
approaches are now operational, which are linked to different paradigms in decision making. It is shown that the choice of
paradigm is quite decisive on the outcome of the analysis. Also within similar paradigms, different methods now operational
may lead to different outcomes. These latter differences may be alleviated more easily than those related to paradigmatic
choices, as they are partly a matter of refinement, and they partly result from legitimate differences in subjective priorities.
The more basic paradigmatic differences can hardly be bridged. The practical relevancy of the subject is proven by applying
different operational methods to one case, showing widely differing outcomes. The paradigm behind evaluating environmental
effects is either values based, directly or through policy decisions, or economics based, as individual preferences measured
in the monetary terms of willingness-to-pay. Accordingly, the different methods are “policy-oriented” or “monetary”. It may
be doubted if the differences between these can be overcome in standardisation. 相似文献
3.
Reinout Heijungs Arjan de Koning Sangwon Suh Gjalt Huppes 《Journal of Industrial Ecology》2006,10(3):147-158
Integrated product policy, according to the European Union, requires reliable data on the impact of consumer products along their life cycles. We argue that this necessarily requires the development of an information tool for hybrid analysis, combining aspects of life-cycle assessment and input-output analysis. A number of requirements in the development of such a hybrid information tool are identified, mainly concerning data and computational structure. For the former, some important points of attention are discussed, whereas for the latter, operational formulas are developed. 相似文献
4.
5.
Previous studies suggest that, besides the maldigestion of lactose in the small intestine, the colonic processing of lactose might play a role in lactose intolerance. beta-Galactosidase is the bacterial enzyme which catalyzes the first step of lactose fermentation in the colon. We propose a practical method to differentiate and identify bacteria with beta-galactosidase activity in faeces which combines a colony-lift filter assay with X-gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside) as substrate for differentiation and the fluorescent in situ hybridization technique for identification. The method was applied to faeces from lactase non-persistent subjects. After 28 subjects had undergone one glucose and two lactose challenges, consistent intolerant (n=5) and tolerant (n=7) groups were defined according to their symptom scores. Of the 28 faecal samples, 80.6% (mean, SD: 12.1, range: 47.8-100%) of the total cultured bacteria were found to possess beta-galactosidase activity, which indicates that the bacterial beta-galactosidase is abundant in the colon. The tolerant and intolerant groups did not differ in the percentage or composition of the bacteria with beta-galactosidase activity or beta-galactosidase activity in faeces. Results suggest that the percentage or composition of the bacteria with beta-galactosidase activity in faeces do not play a role in lactose intolerance. 相似文献
6.
Aminov RI Walker AW Duncan SH Harmsen HJ Welling GW Flint HJ 《Applied and environmental microbiology》2006,72(9):6371-6376
Phylogenetic analysis was used to compare 16S rRNA sequences from 19 cultured human gut strains of Roseburia and Eubacterium rectale with 356 related sequences derived from clone libraries. The cultured strains were found to represent five of the six phylotypes identified. A new oligonucleotide probe, Rrec584, and the previous group probe Rint623, when used in conjunction with a new helper oligonucleotide, each recognized an average of 7% of bacteria detected by the eubacterial probe Eub338 in feces from 10 healthy volunteers. Most of the diversity within this important group of butyrate-producing gut bacteria can apparently be retrieved through cultivation. 相似文献
7.
Enzyme optimization: moving from blind evolution to statistical exploration of sequence-function space 总被引:2,自引:0,他引:2
Directed evolution is a powerful tool for the creation of commercially useful enzymes, particularly those approaches that are based on in vitro recombination methods, such as DNA shuffling. Although these types of search algorithms are extraordinarily efficient compared with purely random methods, they do not explicitly represent or interrogate the genotype-phenotype relationship and are essentially blind in nature. Recently, however, researchers have begun to apply multivariate statistical techniques to model protein sequence-function relationships and guide the evolutionary process by rapidly identifying beneficial diversity for recombination. In conjunction with state-of-the-art library generation methods, the statistical approach to sequence optimization is now being used routinely to create enzymes efficiently for industrial applications. 相似文献
8.
Extensive Set of 16S rRNA-Based Probes for Detection of Bacteria in Human Feces 总被引:13,自引:3,他引:10
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Hermie J. M. Harmsen Gerwin C. Raangs Tao He John E. Degener Gjalt W. Welling 《Applied microbiology》2002,68(6):2982-2990
For the detection of six groups of anaerobic bacteria in human feces, we designed seven new 16S rRNA-based oligonucleotide probes. This set of probes extends the current set of probes and gives more data on the composition of the human gut flora. Probes were designed for Phascolarctobacterium and relatives (Phasco741), Veillonella (Veil223), Eubacterium hallii and relatives (Ehal1469), Lachnospira and relatives (Lach571), and Eubacterium cylindroides and relatives (Ecyl387), and two probes were designed for Ruminococcus and relatives (Rbro730 and Rfla729). The hybridization conditions for the new probes were optimized for fluorescent in situ hybridization, and the probes were validated against a set of reference organisms. The probes were applied to fecal samples of 11 volunteers to enumerate their target bacterial groups. The Phasco741 and Veil223 probes both detected average numbers below 1% of the total number of bacteria as determined with the bacterial kingdom-specific Bact338 probe. The Ecyl387 probe detected about 1.4%, the Lach571 and Ehal1469 probes detected 3.8 and 3.6%, respectively, and a combination of the Rbro730 and Rfla729 probes detected 10.3%. A set of 15 probes consisting of probes previously described and those presented here were evaluated in hybridization with the fecal samples of the same volunteers. Together, the group-specific probes detected 90% of the total bacterial cells. 相似文献
9.
Marieke Gorrée Jeroen B. Guinée Gjalt Huppes Lauran van Oers 《The International Journal of Life Cycle Assessment》2002,7(3):158-166
Linoleum is a floor covering consisting mainly of linseed oil, other vegetable oils, wood flour and limestone on a carrier
of jute. Forbo-Krommenie B.V. commissioned the Centre of Environmental Science (CML) to carry out an Environmental Life Cycle
Assessment for linoleum floors. The goal of this study was to assess the environmental performance of linoleum floors, indicating
possible options for improvement, and assessing the sensitivity of the results to methodological choices. The functional unit
was defined as: 2000 m2 linoleum produced in 1998, used in an office or public building over a period of 20 years. The method followed in this study
is based on a nearly final draft version of the LCA guide published by CML in corporation with many others, which is an update
of the guide on LCA of 1992.
From the contribution analysis, the main contributing processes became clear. In addition, the sensitivity analysis by scenarios
showed that the type of maintenance during use and the pigments used can have a large influence on the results. Major data
gaps of the study were capital goods and unknown chemicals. Sensitivity analysis also showed that these gaps can lead to an
underestimation. Based on this study, some options to improve the environmental performance of linoleum were formulated and
advice for further LCA studies on linoleum was given. 相似文献
10.
Intention, Goal, Scope, Background Input-Output Analysis (IOA) has recently been introduced to Life Cycle Assessment (LCA). In applying IOA to LCA studies, however,
it is important to note that there are both advantages and disadvantages.
Objectives This paper aims to provide a better understanding of the advantages and disadvantages of adopting IOA in LCA, and introduces
the methodology and principles of the Missing Inventory Estimation Tool (MIET) as one of the approaches to combine the strengths
of process-specific LCA and IOA. Additionairy, we try to identify a number of possible errors in the use of IOA for LCA purposes,
due to confusion between industry output and commodity, consumer’s price and producer’s price.
Method MIET utilises the 1996 US input-output table and various environmental statistics. It is based on an explicit distinction
between commodity and industry output.
Results and Discussion MIET is a self-contained, publicly available database which can be applied directly in LCA studies to estimate missing processes.
Conclusion By adopting MILT results in existing, process-based, life-cycle inventory (LCI), LCA practitioners can fully utilise the process-specific
information while expanding the system boundary.
Recommendations and Outlook MIET will be continuously updated to reflect both methodological developments and newly available data sources. For supporting
information sec http:// wwwJeidenuniv.nl/cml/ssp/softwarc/miet. 相似文献