微囊化JS25噬菌体在液态食品中的释放规律及生物防制效果

为了提高JS25噬菌体的稳定性及在不同液态食品中的应用,该研究通过海藻酸钠微囊化JS25噬菌体,对制备的JS25噬菌体微囊粉进行结构表征和稳定性分析,并研究微囊粉在不同液态食品中的释放规律及稳定性,确定其对液态食品的生物防制作用。结果表明,JS25噬菌体微囊粉包埋率可达87.4%;该条件下的微囊粉粒径分布在20~90?m之间,且呈正态分布;并且与浮游态噬菌体相比,微囊化的JS25噬菌体稳定性显著增加至35 d(4℃和20℃)。另外,JS25微囊粉在不同液态食品中均可迅速释放,并有较高的稳定性;鲜牛奶、蛋清液及肉汤中,当S25噬菌体微囊粉添加量分别超过0.1、1.0、2.0 g/kg时,对鲜致病菌有较强的清除作用。说明该工艺可以有效固定JS25噬菌体,并且对液态食品有较高的生物防制作用。因此,海藻酸钠微囊化JS25噬菌体可以用于JS25噬菌体微囊粉的生产加工及液态食品保鲜。     

安康魔芋软腐病的为害及生物防治

对魔芋软腐病在魔芋种植业中的为害及目前的防治措施进行了阐述,针对目前魔芋软腐病防治技术虽然很多,但效果均不理想的现状,提出利用生防菌来防治魔芋软腐病的新途径.     

噬菌体复配抑菌剂对三文鱼中沙门氏菌的抑制与保鲜作用

为控制生三文鱼中沙门氏菌和产品腐败,通过最小抑菌浓度试验和噬菌体稳定性试验筛选出乳酸链球菌素(nisin)、双乙酸钠与沙门氏菌噬菌体SLMP1进行复配,将抑菌剂(噬菌体108 pfu/g、nisin 0.1 mg/g、双乙酸钠2.0 mg/g)单独和复配应用于预先污染了沙门氏菌(104 cfu/g)的生三文鱼片中,在低温下(4?1)℃贮藏,通过测定沙门氏菌、菌落总数、挥发性盐基氮(TVB-N)以及噬菌体效价来评估复配抑菌剂的效果。结果显示,含噬菌体的抑菌剂能显著(P0.05)降低样品中沙门氏菌的数量,含nisin的抑菌剂能显著抑制样品中菌落总数的增长,含双乙酸钠的抑菌剂能显著抑制TVB-N的增加。噬菌体、nisin和双乙酸钠复配抑菌效果最好,在14 d后沙门氏菌低于检测限1 cfu/g,与空白对照相比菌落总数减少了2.5 lg cfu/g,TVB-N值降低了13.73 mg/100 g。结果表明,噬菌体、nisin及双乙酸钠复配剂在生三文鱼沙门氏菌控制及防腐保鲜中具有良好应用前景。     

噬菌体疗法在土壤环境系统中靶向灭活致病细菌的研究进展

由致病细菌导致的新型生物污染土壤问题,已给人体健康和生态环境造成了较严重的安全隐患,开展针对性的风险管控和修复技术研究十分必要。噬菌体疗法作为一种可以高效靶向追踪灭活土壤体系中致病细菌的有效手段,越来越受到关注。本文将从噬菌体疗法定义的内涵及外延、噬菌体疗法在土壤系统中灭活致病细菌的应用及对土壤生态功能影响的角度,综述近年来国内外关于噬菌体疗法在土壤环境系统中靶向灭活致病细菌的研究进展,并提出现有研究不足及未来发展趋势,以期为噬菌体疗法在我国致病细菌污染土壤的治理应用提供科学参考和理论依据。     

噬菌体靶向消减土壤生物污染的制约因素及提升策略

土壤中存在能够威胁植物、动物和人体健康的病原细菌,消减这类土壤生物污染是一体化健康（One Health）的重要任务。因具有宿主细菌专一性强、侵染效率高、环境扰动性小等特性,噬菌体成为生态消减土壤病原细菌生物污染的重要手段。然而,由于土壤生物和非生物环境的复杂性,提升噬菌体消减土壤生物污染的效果和稳定性仍是当前的重大挑战。本文从噬菌体在土壤中的生存以及与病原细菌互作等过程着手,分析总结影响噬菌体阻控土壤生物污染效果和稳定性的主要因素：1）噬菌体的宿主细菌谱和种群数量,2）土壤病原细菌的多态性,3）影响噬菌体与土壤病原细菌互作的环境因素。通过构建高效噬菌体鸡尾酒、改善噬菌体产品形式和优化噬菌体施用技术等措施,建立提升阻控土壤生物污染效果和稳定性的策略,为完善土壤生物污染噬菌体疗法提供科学支撑。     

多价噬菌体分离筛选及靶向灭活土壤病原菌的应用研究

农田土壤中残留和滋生多种病原菌会对人体健康和生态环境带来显著的安全隐患,开展针对性的生物修复研究十分迫切。噬菌体疗法靶向灭活土壤中病原菌的技术为修复此类污染土壤提供了全新途径。本研究以南京城郊某奶牛场牛粪堆积池周边,粪肠杆菌和假单胞菌复合污染农田土壤为例,首先筛选和纯化获得两株专一型噬菌体(YSZ1和YSZ5),再人为加速其宿主谱的表达过程,获得对应的多价噬菌体(YSZ1R和YSZ5K),并进行生物学特性(形态、核酸、最佳感染复数、一步生长曲线等)鉴定,结果表明:在水相和污染土壤中不同噬菌体对于同步灭活病原菌的能力依次为YSZ5KYSZ1RYSZ5YSZ1,并且施用多价噬菌体疗法有助于维护和改善修复后土壤微生物生态功能多样性与稳定性。本研究结果可为噬菌体疗法靶向灭活土壤中多种病原菌提供切实可行的修复技术。     

食品工程用超高压设备的设计及性能试验

为了提高超高压设备的稳定性和处理效率,促进超高压技术应用于食品加工,该文阐述了HHP-700-400L型食品工程用大型超高压设备的工作原理、设计要求、主体结构和工作过程,分析并确定了双向水介质增压器、直推式容器堵头及其密封系统、承压容器材料和结构等相关参数。设备单体容积为100L,总容积为400L;最高工作压力为600MPa;处理能力达到1.68t/h。经性能试验表明:设备性能稳定、操作方便、安全可靠。研究结果为大型商业化超高压设备的设计和制造提供参考。     

条状魔芋食品成条稳定性的研究

利用微电脑变频这一新技术手段来改进现有条状魔芋食品的生产工艺,并对全数字微电脑变频调速器输出频率、魔芋精粉膨化物温度及精粉的使用浓度与条状魔芋食品成条性状和成条稳定性的关系进行了研究。通过多因素组合试验的结果表明:当全数字微电脑变频调速器的输出频率为25Hz、魔芋精粉膨化物的温度为40℃、魔芋精粉的使用浓度为0.028g/mL时,条状魔芋食品的成条性状和成条稳定性最好     

噬菌体对土壤碳氮元素循环转化影响的研究进展

噬菌体是土壤中广泛定殖、数量繁多、严格依赖宿主存活的一类微小生物体,它具有溶原或裂解生命周期,在侵染宿主菌的过程中,不仅可以裂解细菌,还会导致基因转移,显著调控宿主菌数量、物种组成及功能,进而影响土壤元素的生物地球化学循环过程。因而,近年来噬菌体对土壤关键营养元素循环转化的影响机制研究逐渐成为新的学术热点。本文从噬菌体对土壤碳、氮元素循环转化的下行调控和上行调控角度,综述了噬菌体对土壤碳、氮元素循环转化的规律和机制,总结了制约噬菌体调控土壤碳氮循环作用强度的环境因素,指出了当前的研究难点,并对未来研究方向进行了展望。本综述可为阐释噬菌体影响土壤碳氮循环转化机制的研究提供科学参考。     

Hydrogen cyanide production by soil bacteria: Biological control of pests and promotion of plant growth in sustainable agriculture

Currently, plant diseases and insect infestations are mainly controlled by the extraneous application of pesticides. Unfortunately, the indiscriminate use of such agrochemicals can cause ecological and environmental problems, as well as human health hazards. To obviate the potential pollution arising from the application of agrochemicals, biological control of soilborne pathogens or insect pests using antagonistic microorganisms may be employed. Certain soil bacteria, algae, fungi, plants and insects possess the unique ability to produce hydrogen cyanide(HCN), which plays an important role in the biotic interactions of those organisms. In particular, cyanogenic bacteria have been found to inhibit the growth of various pathogenic fungi, weeds, insects, termites and nematodes. Thus, the use of HCN-producing bacteria as biopesticides offers an ecofriendly approach for sustainable agriculture. The enzyme, HCN synthase,involved in the synthesis of HCN, is encoded by the hcnABC gene cluster. The biosynthetic regulation of HCN, antibiotics and fluorescent insecticidal toxins through the conserved global regulatory GacS/GacA system is elaborated in this review, including approaches that may optimize cyanogenesis for enhanced pest control. In addition, the effects of bacterially synthesized HCN on the production of indole acetic acid, antibiotics and fluorescent insecticidal toxins, 1-aminocyclopropane-1-carboxylate deaminase utilization and phosphate solubilization may result in the stimulation of plant growth. A more detailed understanding of HCN biosynthesis and regulation may help to elaborate the precise role of this compound in biotic interactions and sustainable agriculture.     

葡甘聚糖类食品赋味稳定性机理及其应用研究

为了解决葡甘聚糖类食品赋味难且风味不稳定的问题, 通过生物大分子间的相互作用,运用微胶囊等技术对该类食品进行赋味;探讨赋味的机理及其效果、风味的构成、赋味对口感的影响、赋味方法的应用研究等问题.结果表明:β-环状糊精、卡拉胶与黄原胶形成的复配胶壁材,其比例为1.00%∶1.00%∶0.175%时,复配效果最好,凝胶强度最大,包埋效果最好.研制稳定风味的葡甘聚糖类食品既韧又嫩,色、香、味、形俱佳,并已初步探讨了行之有效的赋味方法.     

Most probable number method for isolation and enumeration of Staphylococcus aureus in foods: collaborative study

Enumeration of Staphylococcus aureus in foods was collaboratively studied by comparing the present AOAC final action method, 46.062, which uses trypticase soy broth with 10% NaCl to a proposed replacement method which uses the same broth with 1% sodium pyruvate added. Fifteen collaborators analyzed uninoculated samples of milk, tuna salad, and ground turkey, as well as samples inoculated with low (10(2) cells/g), middle (10(4) cells/g), and high (10(6) cells/g) levels of S. aureus. The samples were frozen immediately to maintain the inoculated level of S. aureus in the food. A different strain of S. aureus was used for each food; heat-stressed S. aureus cells were used to inoculate the milk samples. The pyruvate-amended broth significantly (alpha = 0.05) increased enumeration of low, middle, and high levels of S. aureus from milk and ground turkey, and from tuna salad at middle and high levels. The pyruvate-amended media method has been adopted official first action to replace method 46.062.     

复合微生物制剂改善土壤生物学特性和防治烟草黑胫病的研究

烟草是我国重要的经济作物,利用微生物制剂改善土壤性质,防治烟草土传病害是实现绿色防控的重要途径.利用实验室已筛选的多功能有益微生物进行复配,研究了两种复合微生物制剂T1(芽孢杆菌、假单胞菌、不动杆菌)和T2(芽孢杆菌、假单胞菌、鞘氨醇菌)对土壤理化性质的影响以及对烟草黑胫病的防治效果.结果表明,与未施用微生物制剂的对照...     

Preparation and characterization of the foam-stabilizing properties of cellulose-ethyl cellulose complexes for use in foods

Surface active cellulose particles have been prepared for use as foam stabilizing agents in foods. Various sources of cellulose were broken down by combinations of milling, acid dissolution and treatment with cellulase. The most efficient and simple method was hammer and freezer milling of dry crystalline α-cellulose (Tencel). The resultant Tencel particles were made partially hydrophobic through precipitation of ethyl cellulose (EC) onto them in acetone-water dispersions. The optimum ratio of EC to cellulose and the optimum solids concentration (C(x)) at which to form the complexes were 1:1 and C(x) ≈ 1 wt %, respectively. Complexes combined at low concentrations (e.g., C(x) ≈ 0.1 wt %) with caseins or whey proteins gave significant improvements in stability of foams and bubbles to coalescence and disproportionation compared to either component alone. As such, the complexes could be a useful ingredient in improving the quality of various food foams.     

哈茨木霉协同秸秆对马铃薯黑痣病及根际土壤微生态的影响

为探究哈茨木霉(Trichoderma harzianum)M-33协同小麦秸秆对马铃薯黑痣病的生防效果,及其对马铃薯根际土壤微生物区系的影响,应用平皿对峙法和扫描电镜技术研究哈茨木霉M-33对立枯丝核菌的拮抗机制,通过盆栽试验研究哈茨木霉M-33协同小麦秸秆对马铃薯黑痣病的防治效果和对马铃薯植株生长的影响,基于稀释平板法和高通量测序技术测定协同处理对马铃薯根际土壤微生物区系的影响。结果表明,哈茨木霉M-33对立枯丝核菌的拮抗机制表现为空间竞争和重寄生;协同处理马铃薯出苗率为100%,对马铃薯黑痣病的防效高达70.26%,明显高于对照;协同处理的马铃薯株高、茎粗和分枝数分别为43 cm、0.82 cm和3.89,均明显高于对照;同时,协同处理后马铃薯根际土壤真菌数量较对照降低了29.54%,而细菌、放线菌和木霉菌数量分别较对照提高了75.36%、60.58%和 1 407.27%; 协同处理对真菌群落多样性、群落结构组成影响较大,对细菌群落多样性、群落结构组成影响较小;协同处理能够促进马铃薯根际土壤中有益微生物的聚集。本研究结果可为生防木霉菌高效利用和马铃薯黑痣病的生物防治提供理论基础。     

牡丹花红色素理化性质研究

目前牡丹主要是用于观赏,其综合加工技术没有突破。为了为牡丹花保鲜、护色和色素加工提供理论支持,该文对从牡丹红色品种洛阳红中提取的牡丹红色素进行理化性质研究。结果显示:牡丹红色素水溶性好,颜色随pH值变化而变化。pH值小于3时比较稳定,最大吸收波长为526.5 nm。在酸性条件下该色素对光、热有很好的稳定性;耐氧化性和还原性较差;Zn²⁺、Mg²⁺、Fe²⁺、K⁺、Cu²⁺、Ca²⁺离子对牡丹花红色素的稳定性影响不大,但Sn²⁺、Fe³⁺离子可使色素溶液变色,稳定性差。     

Identification and use of potential bacterial organic antifungal volatiles in biocontrol

Bacteria, isolated from canola and soybean plants, produced antifungal organic volatile compounds. These compounds inhibited sclerotia and ascospore germination, and mycelial growth of Sclerotinia sclerotiorum, in vitro and in soil tests. Ascospore germination in cavity slides was inhibited 54-90% by the volatile producers. When mycelial plugs or the sclerotia, exposed to these volatiles, were transferred to fresh agar plates, the pathogen could not grow, indicating the fungicidal nature of the volatiles. Head space volatiles, produced by bacteria, were trapped with activated charcoal, by passing nitrogen continuously over shake cultures for 48 h. The compounds were eluted from the charcoal with methylene chloride and identified using Gas Chromatography-Mass Spectrometry (GC-MS). The volatile compounds included aldehydes, alcohols, ketones and sulfides. Of the 23 compounds assayed for antifungal activity in divided Petri plates, with filter-disks soaked with these compounds (100 and 150 μl), only six compounds completely inhibited mycelial growth or sclerotia formation, suggesting their potential role in biological control. The compounds are benzothiazole, cyclohexanol, n-decanal, dimethyl trisulfide, 2-ethyl 1-hexanol, and nonanal. Volatiles may play an important role in the inhibition of sclerotial activity, limiting ascospore production, and reducing disease levels. Studies are under way to understand this phenomenon under field conditions. This is the first report on the identification and use of bacterial antifungal organic volatiles in biocontrol.     

A comparison of soil and water properties in organic and conventional farming systems in England

Organic farming and improvements to agricultural sustainability are often seen as synonymous. However, an extensive European review demonstrated that in practice this is not always true. This study aims to compare the status of soil and water properties between separate fields managed in either an organic or a conventional manner. Soil samples were collected from 16 pairs of farms, throughout England, with both arable and grass fields within each pair on similar soil type. Chemical (nutrients, pesticides, herbicides) and physical (aggregate stability, field capacity, shear strength, soil organic matter, infiltration rates) soil properties were measured in four main soil texture classes in organic and conventional fields. The physical soil properties varied significantly between the different classes of texture and land use. The heavier textured soils have significantly higher soil organic carbon (SOC), aggregate stability and shear strength. The coarse‐textured soils have significantly lower field capacity moisture contents. The grassland has a significantly higher level of SOC, field capacity moisture content, aggregate stability and soil shear strength. However, there were no significant differences between organic and conventional treatments for any of the soil physical properties measured. There were fewer traces of agrochemicals in the soil water from the organic fields compared with the conventionally managed fields. The conventional arable fields had higher levels of total inorganic nitrogen than the other land uses and treatments. There was evidence to show that infiltration rates were significantly higher on organically managed grassland soils (7.6 mm/h) than conventionally managed grassland (2.5 mm/h) with lower stocking rates. The results suggest that improved grassland management, whether organic or conventional, could reduce predicted runoff by 28%.     

Biological, chemical and thermal indices of soil organic matter stability in four grassland soils

The various ecosystem functions of soil organic matter (SOM) depend on both its quantity and stability. Numerous fractionation techniques have been developed to characterize SOM stability, and thermal analysis techniques have shown promising results to describe the complete continuum of SOM in whole soil samples. However, the potential link between SOM thermal stability and biological or chemical stability has not yet been adequately explored. The objective of this study was to compare conventional chemical and biological methods used to characterize SOM stability with results obtained by thermal analysis techniques. Surface soil samples were collected from four North American grassland sites along a continental mean annual temperature gradient, each with a native and cultivated land use. Soil organic C concentrations ranged from 6.8 to 33 g C kg⁻¹ soil. Soils were incubated for 588 days at 35 °C, and C mineralization rates were determined periodically throughout the incubation by measuring CO₂ concentration using an infrared gas analyzer (IRGA) to calculate biological indices of SOM stability. Hot-water extractable organic C (HWEOC) contents were determined before and after incubation as chemical indices. Finally, samples from before and after incubation were analyzed by simultaneous thermal analysis (i.e., thermogravimetry (TG) and differential scanning calorimetry (DSC)) to determine thermal indices of SOM stability. Long-term incubation resulted in the mineralization of up to 33% of initial soil C. The number of days required to respire 5% of initial soil organic carbon (SOC), ranged from 27 to 115 days, and is proposed as a standardized biological index of SOM stability. The number of days was greater for cultivated soils compared to soils under native vegetation, and generally decreased with increasing site mean annual temperature. HWEOC (as % of initial SOC) did not show consistent responses to land use, but was significantly lower after long-term incubation. Energy density (J mg⁻¹ OM) was greater for soils under native vegetation compared to cultivated soils, and long-term incubation also decreased energy density. The temperatures at which half of the mass loss or energy release occurred typically showed larger responses to land use change than to incubation. Strong correlations demonstrated a link between the thermal and biogeochemical stability of SOM, but the interpretation of the thermal behavior of SOM in bulk soil samples remains equivocal because of the role the mineral component and organo-mineral interactions.