A Sensitivity Analysis of an Integrated Modelling Approach to Assess the Risk of Wind-borne Spread of Foot-and-mouth Disease Virus from Infected Premises

The sensitivity of an integrated model to assess the potential for wind-borne spread of foot-and-mouth disease (FMD) to variations in key parameters controlling different physical and biological processes was evaluated. The estimated number of farms at risk is sensitive to the virus strain used and the accompanying effective contact rate. The C Noville strain increased the estimated number of exposed farms ranked as high and medium risk of being infected by a factor of 5, compared to the baseline, based on the O UKG 2001 strain. The inclusion of a model for biological ageing of the virus can also have a significant effect on the concentration patterns arising from transport and dispersion of the virus. Its inclusion has the practical advantage of markedly reducing the time required for the calculations. The estimated number of farms affected by exposure to high and medium virus concentrations is not grossly sensitive to attenuation caused by temperature or relative humidity effects. Changes in susceptibility to infection, as determined by the parameter θ in the exposure-risk model, does not change the configuration of the virus plumes, but it does change the distribution of farms at risk by risk category. These findings suggest that a good understanding of characteristics (excretion rates from infected animals, susceptibility of different species to infection, virus survival, etc.) of the virus strain involved in an FMD outbreak is necessary to provide a reliable assessment of the risk of wind-borne spread. In the event of an incursion of FMD, provision for laboratory studies on the virus will be an essential component of the disease response and should be factored into contingency plans.

Characterization of sulfide oxidation and optimization of sulfate production by a thermophilic Paenibacillus naphthalenovorans LYH-3 isolated from sewage sludge composting

The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate and characterize the thermotolerant bacterium that could oxidize sulfide into sulfate, a heterotrophic strain was isolated from sewage sludge composting and identified as Paenibacillus naphthalenovorans LYH-3. The effects of various environmental factors on sulfide oxidation capacities were studied to optimize the sulfate production, and the highest production rate (27.35% ± 0.86%) was obtained at pH 7.34, the rotation speed of 161.14 r/min, and the inoculation amount of 5.83% by employing Box-Behnken design. The results of serial sulfide substrates experiments indicated that strain LYH-3 could survive up to 400 mg/L of sulfide with the highest sulfide removal rate (88.79% ± 0.35%) obtained at 50 mg/L of sulfide. Growth kinetic analysis presented the maximum specific growth rate µ_m (0.5274 hr⁻¹) after 22 hr cultivation at 50°C. The highest enzyme activities of sulfide quinone oxidoreductase (0.369 ± 0.052 U/mg) and sulfur dioxygenase (0.255 ± 0.014 U/mg) were both obtained at 40°C, and the highest enzyme activity of sulfite acceptor oxidoreductase (1.302 ± 0.035 U/mg) was assessed at 50°C. The results indicated that P. naphthalenovorans possessed a rapid growth rate and efficient sulfide oxidation capacities under thermophilic conditions, promising a potential application in controlling sulfur-containing odors during the thermophilic stage of sludge composting.     

驯化菌种降解油制气废水的影响因素研究

利用筛选的3种微生物,在初步研究其对某些化合物降解能力的基础上,考察其降解油制气废水过程中一般因素如温度、pH值、供氧条件、废水浓度以及营养因素如磷源、碳源对微生物降解能力的影响。研究表明,各菌种可在自然环境条件范围内,保持对废水CODCr降解效果的稳定性。葡萄糖、乙醇的加入,可将各菌种对CODCr的去除率分别提高16.9%~26.5%、17.6%~25.6%。     

优势菌种对餐厨垃圾高温好氧消化的促进

为研究优势菌种对餐厨垃圾高温好氧消化(TAD)的促进作用,本研究通过淀粉水解、油脂降解及明胶液化等生化实验,从餐厨垃圾中筛选出若干对其主要成分具有显著降解效果的优势菌种。通过对样品水溶性TOC(TOCw)、水溶性凯氏氮(KNw)、水溶性C/N(KNw)、pH以及含水率等指标的分析,考察优势菌种对餐厨TAD的促进作用。研究表明,优势菌种制剂最优添加量为1%。在此剂量下,好氧消化60 h,TOCw由8.53%降低为2.49%,C/Nw由18.71降低至6.14,以上指标说明加入优势菌种可加速TAD反应。添加量1%样本的水溶性凯氏氮和pH在反应48 h后开始回升,而未添加生物制剂的样本相关参数回升时间需96 h以上,由此推断优势菌种对TAD的促进机制是加快了蛋白质等大分子有机物的降解速度。     

壬基酚降解菌产酶条件的优化

通过单因素试验和正交试验确定了实验室保藏的壬基酚降解菌株沙雷氏菌(Serratiasp.LJ)的最佳产酶条件:以壬基酚、硫酸铵为碳源、氮源,培养基初始pH为6.8,培养温度为30℃,种子活化时间为24h,接种量为3%(体积分数)。在此条件下培养72h后,最高酶活力为1.314IU/mL,是优化前的1.77倍。     

抗铬菌株的筛选鉴定及其生物学特性和吸附特性

利用微生物分离纯化技术,在培养基中加入不同浓度的Cr3+、Cr6+,经过长时间驯化,从污染土壤中筛选出2株对Cr具有较高抗性的菌株(A和B),对其进行了形态、生理生化特性及分子生物学鉴定,并研究了其最佳生长条件及对Cr3+的生物吸附规律。结果表明,菌株A和B分别为蜡状芽孢杆菌(Bacillus cereus)和米根霉菌(Rhizopus oryzae)。菌株A和B的最适生长pH值均为7,最适生长温度均为30℃,最佳装液量为80~100 mL(250 mL摇瓶)。在培养时间一定时,随着Cr3+浓度的增加,菌株对Cr3+的吸附率减少,而生物吸附量则逐渐增大;在Cr3+浓度一定时,随着培养时间的延长,菌体对Cr3+的吸附率呈现出先增加后减少的趋势,这与生物吸附量的变化趋势基本一致。在Cr3+浓度为100 mg/L时,菌株A和B对Cr3+的吸附率达到最大,分别为51.47%和46.36%。     

牛粪堆肥升温菌剂的筛选及其作用机制

以糖、淀粉、蛋白质、纤维素培养基及菌株增殖倍数、菌株性能等为筛选方法,从牛粪低温堆肥中筛选不同原料重要功能菌并组成功能菌剂;以不同类别原料菌及单菌株发酵实验对升温机制进行研究。结果表明,芽孢杆菌、假单胞菌、纤维单胞菌及小孢霉菌等为重要功能菌;菌剂起温快,升温效果好,48 h堆体即由低温进入中温,5 d达到高温,腐熟时间可缩短至约17~18 d;糖功能菌升温效果最为显著,淀粉及蛋白质功能菌次之,纤维素功能菌升温能力较弱;菌株利用各种原料能力越强,增殖速度越快,对升温作用越大。各菌株充分利用基质各成分,紧密协同和促进,是低温堆体发酵升温的主要作用机制。     

水稻耐氨固氮菌施用效应研究

早、晚两季的田间试验结果表明，在电脑推荐施N水平上,耐氨固氮菌的增产效果不显著；在低N情况下(每公顷减纯N37.5kg)，耐氨固氮菌的增产效果达显著水平，早、晚稻分别增产8.41％和7.21％。15N示踪盆栽试验结果表明，耐氨固氮菌对根系生长有明显的促进作用，在秧苗期明显增加秧苗对肥料15N的吸收．禾苗分蘖盛期则增强了禾苗根系的吸氮能力。     

蔬菜作物施用耐氨固氮菌的增产效果

研究在小区试验条件下,施用耐氨固氮型的催娩克氏菌和阴沟肠杆菌混合菌剂对蔬菜生长和产量的影响。结果表明，施用耐氨固氮菌可促进蔬菜生长，提高产量并改善品质，供试蔬菜的平均增产率达20％，增产效果明显。     

微生物育种技术在废水处理工程菌株研制中的应用

随着环境污染的日益严重,仅靠从自然环境中分离筛选有降解酶活菌株的方法已不能适应废水处理实践的要求,需要应用先进的微生物育种技术来更加快速而定向地制备降解工程菌株并用以组成高效的废水生物处理系统.本文从细胞和分子生物学水平综述了国内外应用微生物育种技术研制环保工程菌的部分理论研究进展和应用概况,对各种育种方法的利弊及目前研究中尚存的问题也作了探讨.