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Lien VANDE MAELE Marc HEYNDRICKX Dominiek MAES Nele DE PAUW Maxime MAHU Marc VERLINDEN Freddy HAESEBROUCK An MARTEL Frank PASMANS Filip BOYEN 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2016,78(2):325-328
The antibacterial potential of organic acids and essential oil components against Brachyspira
hyodysenteriae, the causative pathogen of swine dysentery, was evaluated. Minimum inhibitory
concentrations (MIC) of 15 compounds were determined at pH 7.2 and pH 6.0, using a broth microdilution assay.
In addition, possible synergism was determined. MIC values for the three tested strains were similar. For
organic acids, MIC values at pH 6.0 were lower than at pH 7.2. B. hyodysenteriae was most
sensitive to cinnamaldehyde and lauric acid, with MIC values <1.5 mM. Most antibacterial effects of binary
combinations were additive, however, for thymol and carvacrol, synergism could be observed. In
vitro results demonstrate the antibacterial action of certain essential oil components and organic
acids against B. hyodysenteriae. 相似文献
2.
Meelis Prtel Aveliina Helm Nele Ingerpuu Ülle Reier Eva-Liis Tuvi 《Biological conservation》2004,120(4):525-531
Effective biodiversity conservation requires an analysis of the existing reserve system. In temperate and boreal regions, plant diversity has a strong positive association with soil pH. Consequently, in order to protect plant diversity effectively, a relatively large proportion of protected areas should be on high pH soils. Since biodiversity data are never complete for all taxa, biodiversity indicators, e.g., threatened species, should be used. We studied soil pH distributions in protected areas in Northern Europe and tested whether soil pH requirement differs between threatened and non-threatened bryophyte and vascular plant species. As result, the proportion of high pH soils in protected areas was significantly greater than the proportion of these soils in general. This ensures that a large regional pool of plant species preferring high pH soils is relatively well protected. Threatened and non-threatened species in Northern Europe did not differ in their soil pH requirements, but threatened species required a narrower soil pH range than non-threatened species. Consequently, threatened species diversity can be used for indicating overall plant diversity. 相似文献
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Over two consecutive years, weekly examinations for the presence of nematodes were conducted on 185 stomachs from donkeys originating mainly from the Rabat, Casablanca and Settat regions of Morocco. All the animals, except one, were infected by at least one of four helminth species.Trichostrongylus axei was found in 93.5%,Habronema muscae in 89.7%,H. majus in 85.4% andDraschia megastoma in 1.1% of donkeys. Most animals were infected by two (23.8%) or three (71.9%) species. High burdens ofT. axei were observed in the winter of both years and in the mid-summer of the second year. Peak burdens ofHabronema were found at various times throughout both years. There were more adultH. majus thanH. muscae. The periods of peak levels of infection by these parasites were related to environmental conditions suitable for the development and survival of infective larvae ofT. axei and for the build-up of muscid fly vectors ofHabronema andDraschia spp. 相似文献
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Background, aim, and scope Contaminated mine drainage water has become a major hydrogeological and geochemical problem. Release of soluble metal contaminants
and acidity from mining sites can pose serious chemical risks to surface and groundwater in the surrounding environment, and
it is an important socio-economic factor addressed by working groups like SUITMA Morel and Heinrich (J Soils Sediments 8:206–207,
2008). The release of Zn and Pb from sulfide-bearing flotation residues of a small scale mine in Western Germany is investigated
with focus on metal transfer to soil solution. Total contents of the soil material as well as soil water sampled with suction
cups were analyzed. The influence of pH on leaching behavior was investigated with pHstat tests. Isotopic analyses helped assessing seepage water velocity. The aim of this study was the assessment of the environmental
behavior of zinc and lead caused by the weathering of sulfide-bearing mine tailings. Especially, we address in this paper
the dissolution of sphalerite (ZnS) in contrast to the well-known dissolution processes of pyrite (FeS2).
Materials and methods Total metal contents of the soil samples were analyzed by energy-dispersive X-ray fluorescence spectroscopy, total C concentration
was measured using a CHNS elemental analyzer. X-ray diffraction (XRD) spectra were recorded from powdered soil samples. Soil
water was sampled in nylon suction cups. Electrical conductivity (EC), pH, and temperature of the soil water samples were
measured in the field immediately after sampling. Major anions (F, Cl, NO2, NO3, SO4) were analyzed by ion chromatography, major cations (Ca, Na, K, Li) were analyzed by flame photometry, heavy metals (Zn,
Pb, Fe, Mn, and Mg) by flame atomic absorption spectrometry. Tritium was analyzed by liquid scintillation counting (LSC),
18O and 2H were analyzed by isotope ratio mass spectrometry (IRMS). pHstat tests were performed at four different pH values between 2 and 5.
Results Total Zn contents of the soil samples averaged 10 g kg−1, Pb contents averaged 2.5 g kg−1, Fe 22 g kg−1, S 8.0 g kg−1, and total carbon 4.0 g kg−1. Below 2-m depth, soil samples had neutral pH values. Toward the surface, pH decreased down to pH 5.4 in P1 and P3, and to
pH 5.9 in core P2, respectively. Dissolved contents of major ions (Mg, Ca, K, SO4, and HCO3) in the soil solution increased with depth. Metal concentrations (Fe, Mn, Zn) decreased with depth. The solution pH was neutral
to slightly alkaline in samples below 2 m and slightly acidic (pH 6) at 1 m depth. Tritium values are around 7 TU and correspond
to modern rain, i.e., after 1975. Stable isotope values plot on the global meteoric water line. The pHstat tests provide two kinds of information, the acid neutralization capacity after 24 h (ANC24) and the release of metals depending
on pH. The ANC24 increases linearly with decreasing pH from about 60 mmol(eq) kg−1 at pH 5 to about 460 mmol(eq) kg−1 at pH 2. Zn and Fe release show a strong increase with decreasing pH to 126 and 142 mmol(eq) kg−1, respectively. Pb release increases at pH <4 and Mn release at pH <5, both to about 10 mmol(eq) kg−1.
Discussion With an average of 10 g kg−1, this field site is highly enriched in Zn. In the oxidized topsoil, Zn concentrations are significantly lower than in the
anoxic subsoil. The distribution pattern of total Zn contents and soil pH values indicate that the topsoil, which is prone
to oxidation and acidification, is already depleted in Zn. Only in soil core P2, Zn (and Fe) contents in the topsoil were
higher than in the subsoil. Oxidation of the sulfidic material leads to redistribution into mobilizable species. High soil
water concentrations (10 to 15 mg L−1) can be found at acidic pH. The dominant Zn species in the soil solution is Zn2+. At neutral pH, Zn concentrations are below 0.001 mg L−1. During the soil passage, the contaminated seepage water enters the anoxic subsoil with pH buffering carbonates. Results
indicate that Zn is immobilized there. However, when the acid neutralization capacity is exhausted, a breakthrough of dissolved
Zn to the groundwater has to be expected. Lead averages 2.5 g kg−1 inside the flotation dump. In contrast to Zn, the first centimeters of the oxidized topsoil with high TOC contents show higher
Pb contents than the anoxic subsoil. About 80% of the cation exchange capacity in the topsoil is occupied by Pb. In contrast
to Zn, Pb is not abundant as aqueous species at slightly acidic pH. Values lower than pH 4 are necessary to mobilize Pb in
higher amounts, as pHstat experiments confirm. Hence, Pb is not expected to be leached out until the buffer capacity of the soil is exhausted.
Conclusions The environmental fate and behavior of Zn and Pb in the flotation dump is strongly depending on pH and redox conditions. Oxidation
of sphalerite leads to a transfer of Zn from immobile to easily mobilizable species. Sulfide oxidation leads to an acidification
of the topsoil where the buffer capacity is already exhausted due to the leaching of carbonates. At acidic pH, Zn is transferred
to the aqueous phase and leached to the subsoil where soil pH is neutral. Electron supply and the buffer capacity of the material
are found to be the main factors controlling the mobility of Zn. In contrast, the transfer of comparable amounts of Pb to
the aqueous phase requires pH values <4. Since Pb is enriched in the topsoil, not leaching to the groundwater, but direct
uptake (e.g., children, animals) and uptake by plants is the highest environmental risk. If the acidification of the soil
proceeds with the same rate as in the last 40 years, it will reach the bottom of the tailing in about 200 years and a breakthrough
of metals to the groundwater has to be expected.
Recommendations and perspectives The behavior of the different metals and their environmental impact depends on the different metal properties as well as on
external conditions, e.g. pH, redox conditions, buffer capacity, and groundwater recharge. To assess the future release of
metals from a flotation dump it is crucial to determine the main processes leading to acidification, the buffer capacity,
and heavy metal binding forms. The release of heavy metals to the groundwater could be prevented by liming or other buffering
techniques de Andrade et al. (J Soils Sediments 8:123–129, 2008).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Takken W Verhulst N Scholte EJ Jacobs F Jongema Y van Lammeren R 《Preventive veterinary medicine》2008,87(1-2):41-54
The Netherlands has enjoyed a relatively free state of vector-borne diseases of economic importance for more than one century. Emerging infectious diseases may change this situation, threatening the health of humans, domestic livestock and wildlife. In order to be prepared for the potential outbreak of vector-borne diseases, a study was undertaken to investigate the distribution and seasonal dynamics of candidate vectors of infectious diseases with emphasis on bluetongue vectors (Culicoides spp.). The study focused primarily on the relationship between characteristic ecosystems suitable for bluetongue vectors and climate, as well as on the phenology and population dynamics of these vectors. Twelve locations were selected, distributed over four distinct habitats: a wetland area, three riverine systems, four peat land areas and four livestock farms. Culicoides populations were sampled continuously using CO(2)-baited counterflow traps from July 2005 until August 2006, with an interruption from November 2005 to March 2006. All vectors were identified to species level. Meteorological and environmental data were collected at each location. Culicoides species were found in all four different habitat types studied. Wetland areas and peat bogs were rich in Culicoides spp. The taxonomic groups Culicoides obsoletus (Meigen) and Culicoides pulicaris (Linnaeus) were strongly associated with farms. Eighty-eight percent of all Culicoides consisted of the taxon C. obsoletus/Culicoides scoticus. On the livestock farms, 3% of Culicoides existed of the alleged bluetongue vector Culicoides dewulfi Goetghebuer. Culicoides impunctatus Goetghebuer was strongly associated with wetland and peat bog. Many Culicoides species were found until late in the phenological season and their activity was strongly associated with climate throughout the year. High annual variations in population dynamics were observed within the same study areas, which were probably caused by annual variations in environmental conditions. The study demonstrates that candidate vectors of bluetongue virus are present in natural and livestock-farm habitats in the Netherlands, distributed widely across the country. Under favourable climatic conditions, following virus introduction, bluetongue can spread among livestock (cattle, sheep and goats), depending on the nature of the viral serotype. The question now arises whether the virus can survive the winter conditions in north-western Europe and whether measures can be taken that effectively halt further spread of the disease. 相似文献
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Histomoniasis or blackhead is a disease of gallinaceous birds, caused by the protozoon Histomonas meleagridis. Since traditional diagnostics for the detection of this disease are complex and far less sensitive than molecular tools, a PCR would provide a more rapid and sensitive alternative. However, intestinal material and droppings, which are preferably used in epidemiological studies of histomoniasis, often contain PCR inhibitory substances. To detect these false negative results, the use of an internal amplification control is essential. Nevertheless, the recently developed PCR tests lack this internal control. Therefore, a new PCR assay with H. meleagridis specific primers was developed which does include an internal amplification control. The diagnostic value of the PCR assay was evaluated in comparison to three other conventional H. meleagridis specific PCR tests (HIS5, HM1 and HM2). None of the organ samples originating from uninfected turkeys, showed positive PCR results in any of the tests. Among the lesion-positive, inhibition-free samples, 95.4% were positive by our PCR assay, while only 50, 66.7 and 83.3% of the lesion-positive organs tested positive by the HM1, the HIS5 and the HM2 PCR respectively. In conclusion, our PCR offers the use of the internal control to detect false negative results and an increased sensitivity, and thus should be useful for routine diagnosis of H. meleagridis in poultry. 相似文献
8.
Nele Verhulst Ken D. SayreMateo Vargas Jose CrossaJozef Deckers Dirk RaesBram Govaerts 《Field Crops Research》2011,124(3):347-356
Wheat is an important food and income source and estimated demand for wheat in the developing world is projected to increase substantially. The objectives of this study were to gain insight into (i) the effect of tillage-straw system on yield and yield components (number of grains per m2 and thousand kernel weight), (ii) the relation between climatic conditions and yield and yield components, (iii) the explanation of tillage-straw system × year interaction for yield and yield components by climatic co-variables. Wheat grain yield and yield components were measured in a long-term trial established in 1992 under irrigated, arid conditions in northwestern Mexico. Five tillage-straw management systems (conventionally tilled raised beds [CTB] with straw incorporated and permanent raised beds [PB] with straw burned, removed, partly retained or fully retained) were compared for a wheat-maize rotation. Daily climatic data were averaged over six periods corresponding approximately to advancing wheat growth stages. The PB-straw retained and PB-straw removed had the highest yields (average yield of 7.31 and 7.24 t ha−1, respectively) and grains per m2. The PB-straw burned had the lowest yield (average yield of 6.65 t ha−1) and grains per m2, but the highest thousand kernel weight. Maximum temperature was positively correlated to final grain yield during tillering and head differentiation, but was negatively correlated to thousand kernel weight during grain-filling. For the tillage-straw system year interaction, three groups of management systems were distinguished for yield and grains per m2: PB-straw burned, CTB-straw incorporated and PB where straw is not burned. The CTB-straw incorporated had a positive interaction with year in favorable years with high radiation and evapotranspiration. The PB-straw burned was relatively more affected by excess water conditions and showed positive interactions in years with high relative humidity. The PB-straw retained was the most stable in different climatic conditions, indicating that this management system could contribute to maintaining wheat yield in a changing climate scenario. 相似文献
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