JS25噬菌体生物特性及对食品中致病菌的生物防治

该试验以JS25噬菌体为研究对象,在分析稳定性的基础上,确定其对宿主细胞的侵染时间及最佳感染复数,最后通过在即食食品中的抑菌效应确定对即食食品的生物防治效果。结果表明,JS25噬菌体最佳感染复数为0.1、侵染时间为20 min、最适温度及p H值分别为4~60℃和6~9;另外,JS25噬菌体的潜伏期为20 min,60 min后平均裂解量为24.55 PFU/cell;试验结果表明,JS25噬菌体在即食食品中有较高的稳定性,且随噬菌体初始效价的增加,对即食食品中金黄色葡萄球菌的抑制作用也逐渐增加;但是在不同即食食品中的生物防治效果存在差异,主要表现为当效价为108及1010 PFU/g时,能分别有效的抑制鲜牛奶和圆白菜在贮藏过程中的金黄色葡萄球菌数量,当效价大于109 PFU/g时,对肉干及火腿中的致病菌有良好的防治效果。     

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     

贮存温度条件对蔬菜基质中农药残留稳定性的影响

本研究对蔬菜样品中农药残留稳定性和变化趋势进行考察,采用直接在匀浆样本中添加农药的方法,并且为避免每次取出称样反复解冻对农药降解产生影响,进行等分分装密封贮存.温度条件为室温(25℃左右)、冷藏(0～4℃)和冷冻(-18℃左右)；贮存期最长为379天.结果表明,冷冻条件及高浓度农药稳定性较好.不同农药降解趋势不同,其中百菌清稳定性最差,常温时百菌清10天内约降解90％,冷藏和冷冻分别降解40％和20％.毒死蜱、聚酯类农药稳定性较高.不同蔬菜种类间的差异不显著.农药残留通常是微量分析,样品宜冷冻储存,并应在3天内检测.     

适宜贮藏温度和添加剂提高苹果粉稳定性

为提高喷雾干燥苹果粉的贮藏稳定性和优化贮藏条件,基于水分活度保藏理论和玻璃化转变理论,探讨了温度及添加剂对苹果粉吸附等温线和玻璃化转变温度的影响。采用静态称量法研究了苹果粉在不同温度(5、25和45℃)下的吸附等温线;采用Lewicki、GAB、Smith、Henderson和Peleg模型拟合试验数据,得到描述苹果粉水分吸附特性的数学模型;采用差示扫描量热法测定了添加β-环糊精、麦芽糊精、可溶性淀粉和玉米淀粉的苹果粉在贮藏温度40℃达到水分平衡时的玻璃化转变温度;采用Khalloufi,El-Maslouhi,Ratti方程拟合数据,探讨添加剂对苹果粉临界水分活度和临界平衡干基含水率的影响。结果表明,GAB模型为描述苹果粉水分吸附特性的适宜模型;苹果粉的平衡干基含水率随着水分活度的增加而增加,水分活度小于0.76时随着温度的升高而降低;苹果粉的玻璃化温度随平衡干基含水率的增加而降低,添加β-环糊精的苹果粉玻璃化温度较高,不易结块,有利于提高苹果粉的贮藏稳定性。研究可为苹果粉适宜干燥技术条件和贮藏条件的确立提供参考。     

生物炭对向日葵秸秆热解特性及气体产物影响

为了研究生物炭对向日葵秸秆热解的影响,以向日葵秸秆为原料,基于TG-FTIR研究生物炭添加前后向日葵秸秆热解特性与气体产物的变化。结果表明,与向日葵秸秆相比,混合样品主热解区间由276~349℃变得更长,并且发生不同程度的偏移,热解活化能不同程度降低,由60.21降到38.07~50.35 kJ/mol,呋喃类、酸类、含羰基类化合物、芳香醛类、CO、CH4等产物吸光度值存在差异。随着添加500℃制备生物炭比例增加,混合样品热解的活化能减小,释放气体产物中芳香醛类释放量增量减少,CO与CH4释放量降低。添加不同制备温度的生物炭,混合样品热解产生呋喃类、酸类、含羰基类化合物释放量均有所降低;添加500和700℃制备的生物炭,混合样品热解气体产物中芳香醛类增加。添加900℃制备的生物炭,向日葵秸秆热解气体产物中CO产量增加。该研究为向日葵秸秆的有效利用提供理论基础和技术支撑。     

两种不同剂型毒死蜱对四种环境生物的毒性评价

按照化学农药环境安全评价试验准则方法,测定了40%毒死蜱乳油和30%毒死蜱微囊悬浮剂对鱼类、鸟类、家蚕和蜜蜂4种环境生物的毒性。结果表明,毒死蜱乳油对斑马鱼LC50值（96 h）为0.68 mg.L^-1,毒死蜱微囊悬浮剂的LC50为47.30 mg.L^-1;毒死蜱乳油对鹌鹑的毒性LD50为7.45 mg.kg^-1,毒死蜱微囊悬浮剂的LD50为56.97 mg.kg^-1。食下毒叶法结果表明,毒死蜱乳油对2-4龄家蚕幼虫LC50值（48 h,25℃）分别为0.82、1.87 mg.L^-1与4.35 mg.L^-1,毒死蜱微囊悬浮剂为2.48、4.22 mg.L-1与8.35 mg.L^-1;家蚕幼虫在药膜上爬行1、10、30 min与60 min后,毒死蜱乳油对3龄家蚕幼虫的LD50值（48 h,25℃）分别为3.18、0.68、0.41μg.cm^-2与0.38μg.cm^-2,其微囊悬浮剂LD50值分别为6.92、1.58、1.18μg.cm^-2与0.48μg.cm^-2;毒死蜱乳油和微囊悬浮剂对蜜蜂48 h的LC50分别为0.53 mg.L^-1和2.32 mg.L^-1。上述结果表明,毒死蜱微囊悬浮剂对4种环境生物的安全性明显高于乳油。     

天然木粉在包裹控释尿素上的应用

为探究木质纤维素类有机物在缓/控释肥上的应用效果,采用静水浸泡法,研究了3种天然木粉包裹控释尿素(CRU20、CRU25、CRU30)在常温条件下的养分释放规律,以及不同温度、pH值和水肥比对控释尿素养分释放规律的影响。结果表明:1)包裹控释尿素的缓释期随着包裹量的增大而变长,CRU20、CRU25、CRU30的理论缓释期分别为36、54,121d,不同的包裹量表现出不同的释放曲线模式。2)氮素释放速率受温度和pH值的影响较大,不同水肥比的差异不明显。3)包裹控释尿素释放机理为"崩溃"机制。天然木粉包裹控释尿素具有很好的推广应用价值。     

生物炭二级循环折流式冷却中试系统的设计与试验

针对热解炭化后生物炭温度高、冷却慢、余热难以回收等导致热解生产周期长、生物炭热能利用率低的问题,该文采用固-液间接换热原理,设计了循环水二级折流式冷却换热装置并开发了生物炭二级循环冷却中试系统,并对不同生物炭在不同水流量、转速条件下开展试验,试验结果表明,采用该系统后出口生物炭平均温度为30℃,能够满足冷却要求。进出口生物炭温差随水流量的增大而增大,当螺旋轴转速为5 r/min,水流量分别为8、6.5、4 m3/h时,进出口生物炭温差分别为272、242、222℃。水流量固定为6.5 m3/h,螺旋轴转速为25 r/min时,生物炭出炭温度为40℃,而转速降低为5 r/min时,出炭温度降低到25℃;不同生物炭综合传热系数不同,玉米秸秆生物炭冷却时达到最大为100.6 W/(m2·K)。该研究中冷却系统能够与热解炭化设备相匹配,并且满足生物炭连续冷却的需求,可以开展不同生物质炭的冷却试验。     

真空热解松木粉制备生物油

为研究与开拓高品位生物油的制备方法,该文以松木粉为原料,采用真空热解的方法制备生物油。讨论了150～830μm的4种不同粒径大小、400～600℃的5种不同反应温度对真空热解的影响,对其原因进行讨论与分析;并对最优条件下的真空热解气液相产物进行表征。试验结果表明,在500℃反应温度下,250～380μm粒径松木粉真空热解得到生物油产率最高,可达52.06%;真空热解生物油的黏度较低,流动性能好,高附加值化合物较多,这些特性使真空热解生物油作为提取化学品的原料成为可能,该研究为生物质制备高品位生物油提供参考。     

检测食品沙门氏菌的生物传感器持久性研究

为了研究温度对生物传感器检测的持久性的影响,制备了用于检测食品中沙门氏菌的磁致伸缩生物传感器,以磁致伸缩膜片作为物理传感器,多克隆抗体作为生物识别元件,采用Langmuir-Blodgett(LB)技术将多克隆抗体固定在磁致伸缩膜片表面。当食品中沙门氏菌吸附在生物传感器上时,将引起其共振频率漂移。通过测试与分析磁致伸缩生物传感器共振频率漂移值,并利用扫描电子显微镜(scanning electron microscope)观察吸附了沙门氏菌的生物传感器表面,对生物传感器在25(室温)、45及65℃的持久性进行研究。结果表明:多克隆抗体磁致伸缩生物传感器与沙门氏菌的结合能力随着时间的延长逐渐降低;且温度越高,传感器的持久性越差;在25、45及65℃时,多克隆抗体磁致伸缩生物传感器的持久期分别为30、8和5 d,由此获得了多克隆抗体生物传感器在常用温度下的持久性。并结合阿伦尼乌斯方程,计算得到该生物传感器的激活能为13.024 kJ/mol。进一步证实了磁致伸缩生物传感器可用于定量检测实际溶液中沙门氏菌的浓度,表明生物传感器可应用于食品中细菌的实时快速定量检测。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.