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251.
Ahmed Abdel-Megeed Mourad A. M. Aboul-Soud Rudolf Mueller Fredua Agyeman Rudolf Salem S. Al-Deyab 《Journal of Polymers and the Environment》2010,18(4):617-625
A gram-negative psychrophilic bacterium, with potential for biodegradation of long-chain n-alkanes was isolated from ice samples collected in Spitzbergen, Denmark. On the basis of results of biochemical and morphological
tests and sequence analysis of 16S rRNA, the strain was identified as Pseudomonas
frederiksbergensis. In this work, a short-chain NAD+-dependent alcohol dehydrogenase (alcDH) (Accession number: AAR13804) from the P.
frederiksbergensis was cloned and transformed in E. coli BL21 (3DE) competent cells. The alcDH activity was highest in the crude extract of cells induced with 1.0 mM IPTG. The recombinant
alcDH enzyme was purified to 93.4% homogeneity using three consecutive purification steps including ammonium sulphate, Q-Sepharose
Fast Flow column and gel filtration chromatography employing Superdex 200 10/30 HR column. Enzyme enrichment and yield levels
of 31.4 folds and 25.5%, respectively, were achieved. While the subunit molecular mass of the enzyme was determined on SDS-PAGE
to be ~38 kDa, the aggregated native form of the enzyme had a molecular mass of ~238 kDa by gel filtration analysis. Reaction
conditions optima for the recombinant alcDH were determined with propan-1-ol as the substrate. While the optimum pH was 9,
the optimum temperature was 35 °C. The alcDH enzyme exhibited moderate thermal stability with half-lives of 150 min at 55 °C,
27 min at 65 °C and 8 min at 75 °C. Results for kinetic parameters indicated that the apparent K
m value for alcDH with propan-1-ol as the substrate was found to be 1.42 mM and the V
max value was 0.63 mmol mg−1 min−1. Experimental evidence revealed that the recombinant alcDH exhibited a wide range of substrate specificity, with higher levels
of specific activity for aliphatic alcohols as compared to secondary alcohols. Taken together, the present study highlights
the potential of alcDH as a member of cold-adapted enzymes in several key biotechnological applications including environmental
bioremediation and biotransformations. It is envisaged that, with the ongoing screening of microorganisms and metagenomes,
directed evolution approaches and the subsequent overexpression of recombinant proteins, more enzymes will be found that are
suitable for bioremediation purposes. 相似文献
252.
James G. D. Peale Erik Bakkom Fayaz Lakhwala James Mueller Josephine Molin 《补救:环境净化治理成本、技术与工艺杂志》2008,18(4):19-31
Groundwater below an operating manufacturing facility in Portland, Oregon, was impacted by chlorinated volatile organic compounds (CVOCs), with concentrations indicative of a dense, nonaqueous‐phase liquid (DNAPL) release. The downgradient plume stretched under the adjacent Willamette River, intersecting zones of legacy impacts from a former manufactured gas plant (MGP). An evaluation of source‐area and downgradient plume treatment remedies identified in situ bioremediation as most likely to be effective for the CVOC plume, while leaving the legacy impacts for other responsible parties. With multiple commercially available products to choose from, the team developed and implemented a bench test to identify the most appropriate technology, which was further evaluated in a field pilot study. The results of the testing demonstrated conclusively that bioremediation enhanced by in situ chemical reduction (ISCR) using EHC® and KB‐1® was most appropriate for this site, providing outstanding results. The following describes the implementation and results of the tests. © 2008 Wiley Periodicals, Inc. 相似文献
253.
G. Meade K. Pierce J.V. O’Doherty C. Mueller G. Lanigan T. Mc Cabe 《Agriculture, ecosystems & environment》2011,140(1-2):208-217
Nitrous oxide (N2O) and ammonia (NH3) emissions from surface applied high (HN) and low (LN) nitrogen pig manures were measured under field conditions. Manures were band-spread to a winter wheat crop at three growth stages—mid-tillering, stem elongation and flag leaf emergence. The N2O flux rates were measured using the static chamber technique while NH3 volatilisation was assessed using a micrometeorological mass balance technique with passive flux samplers. The N2O emissions were episodic in nature with flux rates observed ranging from 2.8 to 31.5 g N2O–N ha?1 day?1 (P < 0.001). Higher N2O emissions generally occurred after rainfall events. Highest N2O losses were observed from the HN treatment with LN manure use decreasing emissions by 18% (P < 0.03). The NH3 volatilisation rates were highest within 1 h of manure application with 95% of emissions occurring within 24 h (P < 0.001). Cumulative N loss was highest at mid-tillering as low crop canopy cover and increased wind-speeds enhanced NH3 loss (P < 0.001). Highest emissions were measured from the HN manure (P < 0.03). Total ammoniacal N loss ranged from 6 to 11%. Crop N uptake and grain yield were unaffected by application timing or manure type. Therefore, the use of LN manures decreased gaseous emissions of N2O and NH3 without any adverse effects on crop performance. 相似文献
254.
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256.
M. G. Lloyd 《Journal of Environmental Planning and Management》1986,29(1):9-12
The latest evidence relating to the enterprise zone experiment in Britain is provided in a recent report published by the Department of the Environment. The note analyses this evidence to provide an indication of the scale of economic activity taking place within the zones. The note suggests that the simplified planning regime of the enterprise zones actually plays a relatively minor role in facilitating economic change and concludes that more detailed evidence is required in order to achieve a full understanding of the effects of enterprise zones. 相似文献
257.
Arthur R. Bos Girley S. Gumanao Marieke M. van Katwijk Benjamin Mueller Marjho M. Saceda Rosie Lynn P. Tejada 《Marine Biology》2011,158(3):639-648
Archaster typicus, a common sea star in Indo-Pacific regions, has been a target for the ornamental trade, even though little is known about
its population biology. Spatial and temporal patterns of abundance and size structure of A. typicus were studied in the Davao Gulf, the Philippines (125°42.7′E, 7°0.6′N), from February 2008 to December 2009. Specimens of
A. typicus were associated with intertidal mangrove prop roots, seagrass meadows, sandy beaches, and shoals. Among prop roots, specimens
were significantly smaller and had highest densities (131 ind. m−2) between November and March. High organic matter in sediment and a relatively low predation rate seemed to support juvenile
life among mangroves. Size and density analyses provided evidence that individuals gradually move to seagrass, sandy habitats,
and shoals as they age. Specimens were significantly larger at a shoal (maximum radius R = 81 mm). New recruits were found between August and November in both 2008 and 2009. Timing of recruitment and population
size frequencies confirmed a seasonal reproductive cycle. Juveniles had relatively high growth rates (2–7 mm month−1) and may reach an R of 20–25 mm after 1 year. Growth rates of larger specimens (R > 30 mm) were generally <2 mm month−1. The activity pattern of A. typicus was related to the tidal phase and not to time of day: Specimens moved over the sediment surface during low tides and were
burrowed during high tides possibly avoiding predation. This is one of the first studies to document an ontogenetic habitat
shift for sea stars and provides new biological information as a basis for management of harvested A. typicus populations. 相似文献
258.
Johann Sarah Goßen Mira Mueller Leonie Selja Valentina Gustavson Kim Fritt-Rasmussen Janne Wegeberg Susse Ciesielski Tomasz Maciej Jenssen Bjørn Munro Hollert Henner Seiler Thomas-Benjamin 《Environmental science and pollution research international》2021,28(13):16198-16213
Environmental Science and Pollution Research - In situ burning (ISB) is discussed to be one of the most suitable response strategies to combat oil spills in extreme conditions. After burning, a... 相似文献
259.
Srirangam Kumaresan Narayan Yoganandan Frank A. Pintar Wade M. Mueller 《Traffic injury prevention》2013,14(2):87-101
The objective of the present study was to develop three separate age-specific one, three, and six year old pediatric human cervical spine (C4-CS-C6) three-dimensional nonlinear finite element models and to quantify the biomechanical responses. The adult model was modified to create one, three, and six year old pediatric spines by incorporating the local geometrical and material characteristics of the developmental anatomy. The adult human cervical spine model was constructed from close-up computed tomography sections and sequential anatomic cryomicrotome sections, and validated with experimental data. The biomechanical responses were compared with the adult human cervical spine behavior under different loading modes using three approaches. Approach 1: using pure overall structural scaling (reduce size) of the adult model. Approach 2: using three separate age-specific pediatric models incorporating local component geometrical and material property changes. Approach 3: applying the overall structural scaling to the above three pediatric models. All pediatric structures were consistently more flexible than the adult spine under all loading modes. However, responses obtained using the pure overall structural scaling (Approach 1) increased the flexibilities slightly. In contrast, the inclusion of local component geometrical and material property changes to create the three individual pediatric cervical spine models (Approach 2) produced significantly higher changes in the flexibilities under all loading modes. When overall structural scaling effects were added to the three pediatric models (Approach 3), the increase was not considerably higher. White the one year old pediatric model was the most flexible followed by the three and six year old models in flexion and extension, the three year old pediatric model was the most flexible under compression followed by the six and one year old models. The differing biomechanical responses among different pediatric groups were ascribed to the individual developmental anatomical features. The present findings of significant increase in biomechanical response due to local geometry and material property changes emphasize the need to consider the developmental anatomical features in the pediatric structures to better predict their biomechanical behavior. 相似文献
260.
Excessive production of methane has been observed at some remediation sites following the addition of organic hydrogen donors such as (emulsified) oils/lecithin, sugars, and conventional carbon + zero‐valent iron (ZVI) amendments. This is due to the fact that methanogens are commonly the most ubiquitous indigenous microbes in anoxic aquifer settings, and, under enriched environmental conditions, methanogens replicate every one to two hours (whereas Dehalococcoides spp., e.g., double in 24–48 hr). Hence, methanogens often bloom and dominate the microbial ecosystem following the addition of remedial amendments, thereby liberating large amounts of methane gas. There are at least three important consequences of this response:
- By utilizing hydrogen, the methanogens compete with dechlorinating microbes, thus making inefficient use of the remedial amendment (just 20 ppm methane in groundwater represents an approximate 30 percent “waste” of added fermentable substrate (i.e., hydrogen donor)—this is a common and tangible detriment);
- Methanogens can methylate heavy metals and their rapid growth consumes alkalinity, while generating acidity, thereby facilitating multiple potential mechanisms for creating secondary contaminant issues (i.e., arsenic plumes); and
- Elevated methane concentrations can exceed current and pending regulations of <10 to <28 ppm methane in groundwater and/or 0.5 percent by volume methane in soil gas (e.g., 10 percent of the lower explosive limit) and/or indoor air (methane is flammable between 5 percent and 15 percent by volume) and this will induce migration of contaminant vapors potentially causing indoor air issues.