Recovery of associated and internalized Salmonella in broiler skin by stomaching and grinding

The objective of this study was to evaluate the recovery of associated and internalized Salmonella by stomaching and grinding broiler skin during exposure at 4 °C and at room temperature, using a two-strain green fluorescent protein (GFP) labeled cocktail of Salmonella Enteritidis. In the first experiment, broiler skins were immediately taken from eviscerated carcasses and exposed to a Salmonella cocktail containing ∼1 × 10⁹ CFU/ml for 0.5, 6, 12, 24, and 48 h at 4 °C. After each exposure, two 1-min stomachings and subsequent grinding of the stomached skin were conducted to quantify loosely associated (from two stomachings) and tightly associated (from grinding) Salmonella on the skin, respectively. Broiler skins exposed to Salmonella for 24 and 48 h were also examined by confocal microscopy before and after the two stomachings. The 1st and 2nd stomachings recovered an average of 71 and 17% of the Salmonella population, respectively, with an additional 12% of the cells recovered after subsequent grinding, regardless of incubation time. Based on the confocal images, most Salmonella were removed after two stomachings, however a few cells further penetrated from 9 to 29 μm into the skin. In the second experiment, broiler skins were immersed in the same two-strain Salmonella cocktail (∼1 × 10⁸ cells/ml) and dip-inoculated for 2 min with/without stomaching at room temperature. Based on the confocal images, Salmonella penetrated the flat skin surfaces and crevices up to 10 and 68 μm without stomaching, respectively, and up to 62 and 132 μm with stomaching. The presence of free-floating Salmonella cells in the skin crevices indicates that entrapped water is important for bacterial translocation in poultry skin. These findings indicated that extent of observable Salmonella association, penetration, and subsequent recovery from poultry skin is related to both surface topography of poultry skin and method of sample processing.     

Headwater reservoirs weaken terrestrial‐aquatic linkage by slowing leaf‐litter processing in downstream regulated reaches

Leaf litter breakdown is a key process, providing matter and energy to communities inhabiting many headwater streams that flow through forests. This detrital pathway is affected by many human landscape transformations; but it is little known about the impact of small headwater reservoirs on leaf litter decay in streams. Alder leaf litter breakdown rates and associated fauna were studied upstream and downstream of five small water supply reservoirs (surface‐release in rainy autumn‐winters), in the Nerbioi‐Ibaizabal drainage basin (Basque Country, Spain), to assess the effect of impoundment on headwater streams function. Breakdown rates were significantly lower below the dams, mainly associated with a reduction of the density and the biomass of shredders. Among the shredders, Nemouridae and especially Protonemura were less abundant downstream of the dam. Alterations in the physicochemical characteristics of the water due to the reservoirs were negligible throughout our study, and temperature showed only slight variations that could not explain the reduction of the rates. The effect on shredders is likely to be related to differences in the riparian environment and flow regulation by the dams. Copyright © 2010 John Wiley & Sons, Ltd.     

长白山6 种主要森林类型地表凋落物燃烧性实验研究

以长白山黄松蒲林场6 种主要森林类型林地内凋落物为对象,研究长白山林区地表凋落物的燃烧性。在长白山黄松蒲林场的白桦林、针叶混交林、针阔混交林、落叶松林、阔叶混交林和杨树林6 种主要森林类型林地内设置样地,通过外业调查、混合采样的方式收集地表凋落物并进行燃烧实验,测定火蔓延传播的速度、燃烧温度和质量变化。通过改变实验风速、坡度和坡向,研究不同条件对火行为、火蔓延速度和烧损率的影响。实验结果表明：长白山地区地表凋落物的火强度从大到小排序为白桦林、针叶混交林、针阔混交林、落叶松林、阔叶混交林、杨树林,白桦林的火强度最大,为460.23 kW/m,杨树林的火强度最小,为367.09kW/m;风速越大,地表凋落物火蔓延速度越大;风速为6 m/s 时,燃烧过程平均温度最大,烧损率最高,当风速小于2 m/s 或大于8 m/s 时,可燃物无法完全燃尽;上坡火坡度增加时,地表凋落物的火蔓延速度增加,烧损率减小;下坡火坡度增加时,地表凋落物的火蔓延速度减小,烧损率增加。     

Steroid hormones in biosolids and poultry litter: a comparison of potential environmental inputs

Steroid hormones can act as potent endocrine disruptors when released into the environment. The main sources of these chemicals are thought to be wastewater treatment plant discharges and waste from animal feeding operations. While these compounds have frequently been found in wastewater effluents, few studies have investigated biosolids or manure, which are routinely land applied, as potential sources. This study assessed the potential environmental contribution of steroid hormones from biosolids and chicken litter. Hormone concentrations in samples of limed biosolids collected at a waste treatment plant over a four year period ranged from < 2.5 to 21.7 ng/g dry weight for estrone (E1) and < 2.5 to 470 ng/g dry weight for progesterone. Chicken litter from 12 mid-Atlantic farms had averages of 41.4 ng/g dry weight E1, 63.4 ng/g dry weight progesterone, and 19.2 ng/g dry weight E1-sulfate (E1-S). Other analytes studied were 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), testosterone, E2-3-sulfate (E2-3-S), and E2-17-sulfate (E2-17-3).     

The impact of historic land use and modern forestry on nutrient relations of Central European forest ecosystems

In the past forests in Central Europe were not only sources of timber and fuelwood but also sources of nutrients to sustain the human population. The use of forests as pastures is still common in some areas while other formerly widespread practices such as litter raking or pollarding have been abandoned. Harvesting of wood, a material of extremely low mineral nutrient content and of wide C/N-ratio depletes nutrients and acid neutralizing capacity at only moderates rates, harvesting of other biomass fractions has a much more severe impact on forest ecosystems. Soil acidification from intensive biomass harvesting of historic land use equaled or exceeded present soil acidification due to the deposition of air pollutants. As a result of historic land use the majority of Central European forest ecosystems was severely depleted of nutrients and acid neutralizing capacity when modern long-rotation forestry became the dominant form of forest land use. At present high deposition rates of acidifying air pollutants prevent the recovery of forest ecosystems in Central Europe. It has to be noted that ecosystem degradation due to excessive biomass harvesting led to systems which were depleted both in nitrogen and acid neutralizing capacity, while high nitrogen deposition rates from Central European air pollution cause a novel combination of progressive soil acidification and concurrent nitrogen saturation. This combination has a high potential for aggravating mineral nutrient deficiencies and nutritional disorders in forest ecosystems.     

Development of a fungal pre‐treatment process for reduction of organic matter in contaminated soil

BACKGROUND: Combustion at high temperature is a common treatment method for heavily contaminated soils. The capacity of the combustion process is negatively correlated with organic matter content of the soil. Thus, by reducing the amount of soil organic matter, batch size could be increased and the combustion process improved. In this study, the possibility to pre‐treat soil containing high levels of organic matter with white‐rot and litter‐decomposing fungi was examined and scaled up. RESULTS: Calculations based on the CO₂ production in laboratory experiments indicated that 20% of the soil organic carbon would have been degraded in 6 months when treated with Sphaerobolus stellatus and 10% when treated with Stropharia rugosoannulata. In a pilot‐scale experiment with S. rugosoannulata mass loss due to degradation of soil organic matter accounted for 10% of the total weight of the soil in 6 months. CONCLUSION: A fungal pre‐treatment process for contaminated soils with high organic matter content was developed. Good results were obtained with S. stellatus and S. rugosoannulata and the process was successfully scaled up to 300 kg scale. Copyright © 2009 Society of Chemical Industry     

家禽加工中常见的问题及对策

提出了禽类加工中常见的问题和解决办法。     

Hot extraction and characterization of a ligninlike fraction involved in larvicidal effects of decomposed leaf litter against mosquito

Hot water-extraction was performed on decomposed leaf litter in order to solubilize the toxic fraction involved in the dietary interaction against mosquito larvae in subalpine breeding sites. The toxic fraction was partially extracted by water with an optimum temperature of 60°C and recovered in an insoluble form. Phytochemical characterization was achieved through differential enzymatic hydrolyses, using the laccase mediator delignifying system, and aluminum chloride chelation monitored by standard bioassays; comparative spectrophotometric analyses in ultraviolet light after solubilization in acetyl bromide; and comparative reversed-phase high-performance liquid chromatography of the phenolic aldehydes after alkaline nitrobenzene oxidation. The results suggested the involvement of ligninlike compounds in the toxicity of the isolated fraction. Toxicity of this fraction appeared far stronger than that of the crude leaf litter. The involvement of this ligninlike fraction in the dietary toxicity of leaf litter against larval mosquito was then investigated.     

Common structure in the heterogeneity of plant-matter decay

Carbon removed from the atmosphere by photosynthesis is released back by respiration. Although some organic carbon is degraded quickly, older carbon persists; consequently carbon stocks are much larger than predicted by initial decomposition rates. This disparity can be traced to a wide range of first-order decay-rate constants, but the rate distributions and the mechanisms that determine them are unknown. Here, we pose and solve an inverse problem to find the rate distributions corresponding to the decomposition of plant matter throughout North America. We find that rate distributions are lognormal, with a mean and variance that depend on climatic conditions and substrate. Changes in temperature and precipitation scale all rates similarly, whereas the initial substrate composition sets the time scale of faster rates. These findings probably result from the interplay of stochastic processes and biochemical kinetics, suggesting that the intrinsic variability of decomposers, substrate and environment results in a predictable distribution of rates. Within this framework, turnover times increase exponentially with the kinetic heterogeneity of rates, thereby providing a theoretical expression for the persistence of recalcitrant organic carbon in the natural environment.     

Production,Biochemical Characterization and Detergents Application of Keratinase from the Marine Actinobacterium Actinoalloteichus sp. MA-32

The present study is the first report on poultry feathers as a novel, inexpensive substrate for the production of a thermo‐ and detergent stable keratinase from a marine actinobacterium belonging to the genus Actinoalloteichus. Medium composition and culture conditions for the keratinase production by Actinoalloteichus sp. MA‐32 were optimized using two statistical methods: Plackett–Burman design was applied to find the key ingredients and conditions for the best yield of enzyme production and central composite design used to optimize the concentration of the five significant variables: whole chicken feather, soy flour, MgSO₄·7H₂O, KH₂PO₄ and NaCl. The medium optimization resulted in a 19.30‐fold increase with a 31.99 % yield with a specific activity of 3842.57 U mg^?1 and the molecular weight was estimated as 66 kDa. The enzyme was optimally active at pH 8–10 and temperature 50–60 °C and it was most stable up to pH 12 and 10–14 % of NaCl concentration. The enzyme activity was reduced when treated with Hg²⁺, Pb²⁺, Tween‐80, 1,10‐phenanthroline and EDTA and stimulated by Fe²⁺, Mg²⁺, Cu²⁺, Ca²⁺, Ni²⁺, Mn²⁺, SDS, ethoxylated (9.5EO) octylphenol, DMSO, sodium sulfite and β‐mercaptoethanol. The keratinase exhibited a significant stability and compatibility with most of the tested commercial laundry detergents, demonstrating its feasibility for inclusion in laundry detergent formulation. These results suggest that this extracellular keratinase may be a useful alternative and eco‐friendly route for handling the abundant amount of waste feathers or for applications in detergent formulation and other industrial processes.