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11.
Heath E Brown WA Jensen SR Bratty MP 《Journal of industrial microbiology & biotechnology》2006,33(3):197-207
The biodegradation of chlorinated alkanes was studied under oxic conditions with the objective of identifying favorable and
unfavorable intramolecular chlorination sequences with respect to the enzymes studied. Several dehalogenating bacterial strains
were screened for their ability to degrade middle-chain polychlorinated alkanes as well as a commercial mixture. Of the organisms
tested, the most promising was Pseudomonas sp. strain 273, which possesses an oxygenolytic dehalogenase. The effects of carbon chain length (C6–C16), halogen position, and overall chlorine content (14–61% w/w) were examined using both commercially available compounds and
molecules synthesized in our laboratory. The effects of co-substrates, solvents, and inducing agents were also studied. The
results with pure chlorinated alkanes showed that the relative positions of the chlorine atoms strongly influenced the total
amount of dehalogenation achieved. The greatest dehalogenation yields were associated with terminally chlorinated alkanes.
The α- and α,ω-chlorinated compounds yielded similar results. Vicinal chlorination had the most dramatic impact on degradation.
When present on both ends or at the center of the molecule, no dehalogenation was detected. Although partial dehalogenation
of 1,2-dichlorodecane was observed, it was likely due to a combination of β-oxidation and an abiotic mechanism. Cereclor S52
was appreciably dehalogenated in shake flasks only when 1,10-dichlorodecane was present as a co-substrate and after increasing
the oil surface area through mechanical emulsification, demonstrating the importance of abiotic factors in degrading commercial
polychlorinated alkane mixtures. 相似文献
12.
Domenico MartiniMaura Pellei Claudio Pettinari Brian W. SkeltonAllan H. White 《Inorganica chimica acta》2002,333(1):72-82
The reaction between CuX2 (X=ClO4, NO3, Cl, Br and CH3COO) and excess of tris(pyrazol-1-yl)methane ligands L (L=CH(pz)3, CH(4-Mepz)3, CH(3,5-Me2pz)3, CH(3,4,5-Me3pz)3 or CH(3-Mepz)2(5-Mepz)) yields [CuX2(L)], [{CuX2}3(L2)2] or [Cu(L2)]X2-type complexes. The ligand to metal ratio is dependent on the number and disposition of the Me substituents on the azole-type ligand and mainly on the nature of the counter-ion X. All complexes have been characterized in the solid state as well as in solution (IR and UV spectra, and conductivity determinations). The solid-state structures of [Cu{(3,5-Me2pz)3CH}2](NO3)2, [Cu{(3,5-Me2pz)3CH}2](ClO4)2·0.5H2O, [Cu{(3,4,5-Me3pz)3CH}2](NO3)2·H2O, [Cu{(4-Mepz)3CH}2]Br2·3H2O have been determined by single crystal X-ray studies. 相似文献
13.
Albert D. Venosa Kenneth Lee Makram T. Suidan Susana Garcia-Blanco Susan Cobanli Moustafa Moteleb John R. Haines Gilles Tremblay Melynda Hazelwood 《Bioremediation Journal》2002,6(3):261-281
Biostimulation by nutrient enrichment and phytoremediation were studied for the restoration of an acutely stressed freshwater wetland experimentally exposed to crude oil. The research was carried out along the shores of the St. Lawarence River at Ste. Croix, Quebec, Canada. The research determined the effectiveness of fertilizer addition in enhancing the biodegradation rates of residual oil. It further examined the rate at which the stressed ecosystem recovered with and without the addition of inorganic fertilizers and the role of nutrients in enhancing wetland restoration in the absence of healthy wetland plants. Chemical analysis of integrated sediment core samples to the depth of oil penetration within the experimental plots indicated that addition of inorganic nutrients did not enhance the disappearance of alkanes or PAHs. In surface samples, however, hydrocarbon disappearance rates were higher when the metabolic activity of wetland plants was suppressed by the removal of emergent plant growth. These results suggest that oxygen limitation plays a major role in preventing rapid biodegradation of hydrocarbons in anoxic wetland sediment. 相似文献
14.
15.
J. A. Zygadlo R. E. Abburra D. M. Maestri C. A. Guzman 《Plant Systematics and Evolution》1992,179(1-2):89-93
The alkane and fatty acid composition of the lipid extracts from leaves of 14 populations ofCondalia: C. microphylla f.xanthocarpa, C. microphylla f.erythrocarpa, C. microphylla f.melanocarpa, C. montana, andC. buxifolia, were determined by gas chromatography. Seventeen alkanes and 14 fatty acids were investigated and a predominance of nonacosane, hentriacontane, palmitic and linoleic acids in all species was found. 相似文献
16.
《Chirality》2017,29(8):415-421
The objective of this pen‐and‐paper study is to witness the emergence of stereoisomeric properties when comparing lower to higher families of homologs. Specifically, the study compares all acyclic hexanes (five constitutional isomers, a.k.a. regioisomers), all nine heptanes, all 18 octanes, all 35 nonanes, and all 75 decanes. The first part of the work examines the nature and number of stereoisomeric properties seen to emerge in chemical structures featuring one chiral center (i.e., enantiomerism) or two such centers, in which case more complex stereoisomeric features emerge (enantiomerism, diastereoisomerism, pseudoasymmetry, and meso ‐isomers). The first emergence of chirality (i.e., enantiomerism) occurred in some heptanes. Diastereoisomerism and meso ‐isomers appear with some octanes, while a pseudoasymmetric center exists in a decane regioisomer. The second part of the work is an attempt to rationalize the numbers of regioisomers, chiral centers, and stereoisomers as these numbers grow from one family of regioisomers to the higher ones. Far from being random, such increases prove regular and ordered. 相似文献
17.
Swapnadip Thakur Prantika Das Toshihiro Itoh Kazunori Imai Taro Matsumoto 《Phytochemistry》1984,23(9):2085-2087
The hexane and methanol soluble extract of the latex coagulum of Calotropis gigantea afforded two new triterpene esters, viz. 3′-methylbutanoates of α-amyrin and ψ-taraxasterol, besides the known 3′-methylbutanoates of three triterpene alcohols. The compositions of the alkane fraction, total triterpene alcohol fraction, and free, acetyl and 3′-methylbutanoyl triterpene alcohol fractions of the extract were determined. 相似文献
18.
A strain of long-chain alkane–degrading bacteria, BT1A, was isolated from oil-contaminated soil in Diyarbak?r, in the southeast of Turkey. Morphological, biochemical, and physiological characterization and 16S rRNA gene sequence analysis showed that the strain BT1A was a member of Acinetobacter genus, and it was found to be closely related to Acinetobacter baumannii. The strain BT1A was able to utilize crude petroleum as carbon and energy sources in order to grow. Among the aliphatic hydrocarbons, growth was observed only in the medium containing long-chain alkanes (tridecane, pentadecane, and hexadecane) and squalene. Hexadecane was the most preferred hydrocarbon among the long-chain alkanes. Gas chromatography–mass spectrometry (GC-MS) analysis showed that BT1A degraded 83% of n-alkanes of 1% crude oil in 7 days. The present study indicates that the isolated strain can well be used for biodegradation of hydrocarbons in oil-contaminated sites. 相似文献
19.
《Animal : an international journal of animal bioscience》2017,11(10):1708-1717
The number of horses in northern Spanish mountains has increased in recent decades, but little is known about their grazing behaviour, performance and potential for foal meat production. This research aimed to study the diet selection, liveweight (LW) changes and parasitic status of dry and lactating mares, and foals’ LW gains, grazing on heathlands with different botanical composition. The experimental design consisted of three vegetation types: dominated by heather (Ericaceae) species (H), dominated by gorse (Ulex gallii; G) and co-dominated by gorse and heath-grasses (G-G), with four replicates per treatment (12 paddocks of 1.2 ha). The study lasted three grazing seasons (2010–12). Each year, 24 crossbred mature mares (310±52 kg LW) were used, managing one lactating mare with her foal plus one non-lactating mare per paddock from May to late summer or early autumn. In the case of H paddocks, animals had to be removed before (late August to early September) because of apparent loss of body condition. Animals were periodically weighed. Mares’ diet composition was estimated using alkane markers, analysing the discrepancies in alkane concentrations between dietary plant components and faeces. Faecal samples were also analysed for gastrointestinal nematodes ova. Chemical composition of the main plant components (i.e. heather, gorse and grasses) revealed a low nutritive value, averaging 79, 115 and 113 g CP/kg dry matter (DM), respectively, that could restrict livestock performance. Mares initially selected gorse and grasses (0.47 and 0.40, respectively, in 2010), increasing heather consumption over time (from 0.13 in 2010 to 0.29 in 2012) as gorse availability decreased. The performance of both mares and foals was lower in H compared with G and G-G paddocks (−216 v. 347 g/day for mares, P<0.01; 278 v. 576 g/day for foals, P<0.05), whereas LW changes were more favourable in dry mares than in lactating ones (241 v. 78 g/day; P<0.05). Small strongyle (Cyathostominae) egg counts in mares’ faeces increased across the grazing season with no differences between treatments. These results indicate that grazing by horses on gorse- and grass-gorse-dominated shrublands could be sustainable at least during part of the year (4 to 6 months). However, heather-dominated heathlands are not able to meet the nutritional needs of horses even for a short time (2 to 4 months). Nevertheless, the low nutritive quality of these vegetation communities, especially in autumn, requires animal access to other pastures with a higher nutritive value, or supplementary feeding, to enhance foals’ growth and maintain sustainable grazing systems with productive herds. 相似文献
20.
Grasslands can be a complex mixture of plant species. A method is described to allow the identification of both roots and shoots of five different grass species, thus permitting greater knowledge about whole plant allocation and competition in mixed pastures. The five species were Lolium perenne, Festuca ovina, Festuca rubra, Poa trivialis and Agrostis capillaris. N‐alkanes with odd‐numbers of carbon atoms in the chains predominate in plants and in the five grass species studied, concentrations of alkanes of chain length of C29, C31 and C33 were highest. Average concentrations of C27‐C33 alkanes in shoots and roots were 187 and 11 mg kg ? 1, respectively. This wide range of values required considerable modifications to the method of analysis, including expressing concentrations on an organic matter basis and scaling‐down the procedure. The n‐alkane concentrations in roots are different from those in shoots and therefore values from shoots cannot be used to predict the composition in roots. Using a canonical variate analysis, all five grass species could be separated using concentrations of C26, C31 and C33 values in the roots. The greatest difference occurred between A. capillaris and the others, whereas discrimination was least between the two Festuca species. Defoliation had contrasting effects on the concentration of a few n‐alkanes, but not in the n‐alkanes used to discriminate between grass species. Alkane analysis shows great potential as a method to quantify the species composition of the root biomass beneath mixed pasture species. 相似文献