Identification of a new Hazelnut disease in Liaoning Province: Hazelnut husk brown rot

Hazelnut husk brown rot has been identified as a new disease in Liaoning Province in recent years. The objective of this study as to identify the pathogen. [Method] In this study, a standard sample of hazelnut husk brown rot was collected from Songmudao Base in Dalian City, Liaoning Province. The pathogen was identified by the studies of the morphology, pathogenicity, and analyses of ITS and LSU sequences. The pathogen was isolated and purified, which was confirmed by Koch’s postulates. The symptoms after inoculation were the same as those collected directly from a diseased tree, which showed that it was the pathogenic fungus. The cultural characteristics and conidia and the morphology of the pathogenic fungi were similar to those of Botrytis cinerea’s. The ITS sequences and LSU sequences were compared to the associated strain sequences in GenBank, with 100% identity to Botrytis cinerea (GenBank accession number: MN589848.1) and Botrytis cinerea (GenBank accession number: KU140653.1), respectively. The infection status of the pathogen on the hazelnut husks was also observed. The studies suggested that the pathogen leading to the hazelnut husk brown rot as a new disease in Liaoning Province was Botrytis cinerea.     

电荷对粉尘和病原体团聚影响的数学模型研究

由于封闭畜禽舍内聚集了大量的粉尘和病原体,将影响到动物和饲养人员的呼吸道健康,因此迫切需要研究去除粉尘和病原体的方法。以粉尘和病原体的结合体为研究对象,利用蒙特卡罗法及相关概率模型,研究电荷对粉尘和病原体团聚影响。通过研究粉尘和电荷间的附着模型,确定其附着受粒子半径、电荷情况、风速等因素影响;之后,进一步构建粉尘、病原体间以及病原体、电荷间的附着模型。结合数值化运算设定边界条件,得出三者间的结合率可达到15%。粉尘、病原体与电荷相互之间模型的建立能有效的了解到畜禽舍除尘的方法,提高除尘效率,并为高压静电除尘的推广和应用提供了理论基础。     

Optimization of PCR-based methods for rapid detection of Campylobacter jejuni, Campylobacter coli and Yersinia enterocolitica serovar 0:3 in wastewater samples

PCR-based methods were evaluated for their adequacy to assess the removal of pathogens from wastewater samples. For the development and optimization of the methods, samples were taken at two different sites from two different constructed wetlands. Campylobacter jejuni/coli and Yersinia enterocolitica serogroup 0:3 were selected as model pathogens and Enterococcus faecalis as a standard microbiological indicator. The chosen PCR protocols were optimized for wastewater DNA extracts in order to obtain high sensitivity and reproducibility independently of the background flora. All PCR protocols were successfully performed and reproducible with a background of up to 10(10) nontarget cells per reaction. Five cells of Y. enterocolitica, 50 cells of C. jejuni/coli, and 500 cells of E. faecalis per 100ml treated water could be detected. The method detection limit in the settled wastewater was higher: 200 cells per 100ml for Y. enterocolitica, 2000 cells per 100ml for C. jejuni/coli, and 20,000 cells per 100ml for E. faecalis. C. jejuni/coli and Y. enterocolitica PCRs were adapted to municipal wastewater, with higher loads of potential PCR inhibitors. Sensitivity was lower for this type of wastewater: 200 cells of Y. enterocolitica and 2000 cells of C. jejuni/coli were detected per 100ml treated wastewater, 2500 cells of Y. enterocolitica and 25,000 cells of C. jejuni/coli per 100ml settled wastewater. The developed PCR methods enable the detection of C. jejuni/coli, Y. enterocolitica serogroup 0:3 and E. faecalis within 12h. They show specificity, reproducibility and low detection limits for the investigated pathogens.     

Mechanisms of microwave irradiation involved in the destruction of fecal coliforms from biosolids

Microwaves have been found to be effective in destructing pathogens in sewage sludge (biosolids) (75th Annual Water Environment Federation Conference, Chicago, September 29-October 2, 2002; Third World Water Congress, International Water Association, Melbourne, Australia, April 7-12, 2002). Mechanisms and roles of microwaves on fecal coliform destruction were investigated using bacterial viability tests, electron transport system (ETS) and beta-galactosidase activity assays, gel electrophoresis, and genomic deoxyribonucleic acid (DNA) optical density (OD) measurements with fecal coliforms isolated from biosolids. Bacterial viability tests demonstrated cell membrane damage as microwave irradiation intensity and temperature increased. Above 60+/-3 degrees C, viable cells were rarely found when pure fecal coliforms were irradiated with microwaves. ETS and beta-galactosidase activity assays revealed increased activity for externally heated samples due to fecal coliform growth but decreased activity for microwave-irradiated samples as temperature was increased from 20 degrees C to 57 degrees C, indicating other destruction mechanisms besides heating. Between 57 degrees C and 68 degrees C, microwave irradiation led to a more rapid decrease in activity than external heating by convection. Above 68 degrees C, bacterial activity almost ceased for both pretreatments. DNA bands in gel electrophoresis tests and OD of genomic DNA decreased more rapidly for microwave-irradiated samples than for externally heated samples, implying that microwaves disrupted DNA in fecal coliform cells at lower temperatures than external heating. Microwave irradiation of sludge appears to be a viable and economical method of destructing pathogens and generating environmentally safe sludge.     

不同来源的副溶血性弧菌定性定量分析及毒素基因检测

目的研究受污染海产品、海产品养殖水及食物中毒临床分离的副溶血性弧菌的生化特性、种特异性基因片段检测方法的应用和毒素基因携带情况。方法66株副溶血性弧菌采用全自动微生物鉴定、MPN值定量、氯化物含量(离子色谱法)、R72H基因片段和tdh、trh毒素基因PCR检测等方法进行研究。结果定性定量分析方面,98.5%的菌株不发酵阿拉伯糖;牡蛎样本MPN值均为≥24000/100g,并检出2株携带trh毒素基因;23/30份养殖水检出副溶血性弧菌,其中海丰监测点6份阳性水样的氯化物含量均值仅为3160mg/L,显著低于实验室培养的30g/L的含量。基因检测方面,VITEK鉴定R72H基因片段结果与检测相符;13株食物中毒临床分离株均携带tdh毒素基因;6.7%的海产品分离株、15.4%食物中毒临床来源株同时携带两种毒素基因。结论通过从海产品和养殖水的检出情况以及分离株的生化特性、毒素基因资料,为副溶血性弧菌食物中毒溯源提供重要的数据源。     

Opportunities for mitigating pathogen contamination during on-farm food production

Fruits, vegetables, and meat are susceptible to contamination by foodborne pathogens at many points from production through preparation in the home. This review will largely highlight approaches and progress made in the last five years to address strategies to reduce pathogen contamination in animal production but will also touch on the emerging field of preharvest produce food safety. Mitigation strategies can be divided into those that address pathogen reduction in the environment and those that target reduction/elimination of pathogen contamination in animals or plants. The former strategy has been encompassed in studies evaluating sanitation treatments of facilities as well as in numerous epidemiologic risk assessment studies (both on-farm assessments and computer simulation models) that identify management practices that impact pathogen prevalence in animals. Interventions to significantly reduce pathogen exposure via feed or water are dependent on their role as a significant contributor to pathogen contamination in the animal production system. In addition, inconsistent results obtained with interventions of dietary additives or formulation modifications (grain versus forage; inclusion of distiller's grains) on pathogen prevalence in animals have been attributed to a range of factors including target organism, grain type, level of inclusion, the animal's health or stress level, and ability to survive the gastric acidic conditions. Recent attempts to microencapsulate organic acids or bacteriophage within feed have met with only marginal improvements in reducing pathogen carriage in animals but this approach may have greater potential with other antimicrobial additives (i.e., essential oils). Bacteriophage therapy, in general, can significantly reduce pathogen carriage in animals but based on its transient nature and the potential for development of phage-resistant subpopulations, this approach should be administered to animals just prior to slaughter and preferably to animals that are suspected “super-shedders”. Other promising on-farm intervention approaches have included breeding for pathogen resistance, vaccines, and dietary bacteriocins. To optimize interventions on a cost basis, studies have also determined that application of dietary interventions at specific time points in the animal's production cycle is a useful strategy to reduce pathogen carriage (e.g., probiotics to fertilized eggs and acidified feed to fattening swine). In conclusion, applicable management and intervention strategies may vary depending on the type of food under production; however, it is important to consider from a holistic view how any new intervention strategies will affect the overall production system in order to maintain a successful, efficient food production environment.     

Characterization of the Effluent Wastewater from Abattoirs for Land Application

Meat plant wastewater quality depends on water usage, the type of animal slaughtered, and the amount of rendering or processing that is done on site. In Ontario and Quebec, abattoir wastewater total chemical oxygen demand (TCOD) ranged from 2333 to 8627 mg/L, and suspended solids (SS) from 736 to 2099 mg/L, volatile suspended solids (VSS) represented 80% of SS, and protein content varied from 444 to 2775 mg/L. Nitrogen (N) and potassium (P) averaged 6.0 and 2.3 g/100 g of TCOD, respectively. Ammonia and sulfide levels were well below the 3000 and 100 mg/L toxicity level, respectively. The chemical oxygen demand (COD) of fresh blood is high at 375,000 mg/L compared to the COD of liquid manure at 15,000-30,000 mg/L. The concentration of the wastewater can be greatly affected by the efficiency of blood recovery in the blood pit. Abattoir wastewater contains several million colony forming units (cfu) /100 mL of total coliform, fecal coliform, and Streptococcus groups of bacteria. The presence of these nonpathogenic microbes indicates the possible presence of pathogens of enteric origin such as Salmonella ssp. and Campylobacter jejuni and of gastrointestinal parasites such as Ascaris sp., Giardia lamblia, Cryptosporidium parvum, and enteric viruses. Giardia lamblia and Cryptosporidium parvum are not a concern in poultry wastewater. Pathogens might threaten public health by migrating into groundwater or through traveling off-site by surface water, wind, or vectors (i.e., animals, birds) etc. Once the treated abattoir wastewater is applied to land, the potential for spread of any pathogens that might remain in the water or sludge varies with the type of crop and soil to which it is applied.     

Use of linear, Weibull, and log-logistic functions to model pressure inactivation of seven foodborne pathogens in milk

Survival curves of six foodborne pathogens suspended in ultra high-temperature (UHT) whole milk and exposed to high hydrostatic pressure at 21.5 degrees C were obtained. Vibrio parahaemolyticus was treated at 300 MPa and other pathogens, Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus were treated at 600 MPa. All the survival curves showed a rapid initial drop in bacterial counts followed by tailing caused by a diminishing inactivation rate. A linear model and two nonlinear models were fitted to these data and the performances of these models were compared using mean square error (MSE) values. The log-logistic and Weibull models consistently produced better fits to the inactivation data than the linear model. The mean MSE value of the linear model was 6.1, while the mean MSE values were 0.7 for the Weibull model and 0.3 for the log-logistic model. There was no correlation between pressure resistance and the taxonomic group the bacteria belong to. The order, most to least pressure-sensitive, of the single strains tested was: V. parahaemolyticus (gram negative)相似文献   

ATP-regulation of antioxidant properties and phenolics in litchi fruit during browning and pathogen infection process

The impact of energy level on antioxidant properties in relation to pericarp browning and loss of disease resistance of litchi fruit was investigated. Litchi fruits were vacuum-infiltrated with distiled water (control), 1 mM adenosine triphosphate (ATP) and 0.5 mM 2,4-dinitrophenol (DNP) under 75 kPa for 3 min before being inoculated with Peronophythora litchi or not. ATP-treated fruits presented higher activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX). Higher activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, reducing power and contents of phenolic compounds were also observed in ATP-treated fruit during storage. In contrast, DNP treatment lowered the enzymes activities, scavenging ability and the contents of phenolic compounds. Higher levels of antioxidant enzymatic system and non-enzymatic system were observed in P. litchii-inoculated fruits than those in non-inoculated fruits. Application of ATP and DNP exhibited a similar change patterns and effects in inoculated fruits. When related to previously reported ATP levels, the results suggested that ATP levels could regulate the antioxidant system. Sufficient available energy is crucial for inhibiting browning and preventing the loss of disease resistance in harvested litchi fruit.