乙草胺降解菌Y-4的分离鉴定及降解特性研究

从长期经乙草胺污染的污泥中分离到一株能以乙草胺为唯一碳源和能源生长的菌株Y-4,通过生理生化实验和16S rDNA同源性序列分析,鉴定为申氏杆菌属（Shinella sp.）。采用室内培养方法,研究了Y-4对乙草胺的降解特性。结果表明,Y-4能有效地降解浓度为5～200 mg.L-1的乙草胺,在48 h内对50 mg.L-1乙草胺的降解率达到83.3%。菌株Y-4降解乙草胺的最适pH值为8.0,最适温度为30℃,其对丙草胺和丁草胺等农药也有良好的降解效果。     

一株红壤花生根际溶磷真菌的分离、鉴定及溶磷能力的研究

为提高磷素利用率,从花生根际土壤样品中筛选到一株溶磷能力强的菌株B1-A,结合菌落形态特征和ITS rDNA序列分析将其鉴定为黑曲霉(Aspergillus niger)。菌株B1-A的不同接种量(1%,3%,5%)在两种难溶性磷酸盐(FePO4,AlPO4)培养液的溶磷量和pH随时间动态变化表明溶磷量均与pH呈显著负相关,B1-A的溶磷量与接种量、培养时间、磷矿粉浓度有关,实验结果表明菌株B1-A在接种量为3%～5%、培养时间168 h、云南磷矿粉浓度为3 g L-1、江西磷矿粉浓度为5 g L-1时溶磷效果较好。菌株B1-A对磷酸三钙、磷酸铝、磷酸铁、磷矿粉有较强的溶解能力,最高溶磷量分别为418.7、942.3、242.2、177.4 mg L-1,有望为开发高效红壤微生物磷肥提供种质资源。     

一株根际好氧反硝化菌的筛选及其反硝化条件研究

为丰富好氧反硝化菌株种类,本文从不同环境样品中富集筛选好氧反硝化细菌,最终得到一株高效根际菌株RWX31,其在初始NO3--N浓度140 mg/L时24 h去除率为82％,并在好氧条件下可进行反硝化作用产生N2O.通过单因素试验研究该菌株进行反硝化作用的条件和特性,结果表明,菌株RWX31最适培养基条件分别为:以柠檬酸钠为碳源,接种量为1％,Mg2+浓度为0.05 g/L,反硝化初始氮源中NO2--N比例为0.最适培养条件为:温度28℃～32℃,pH为7.0～7.5,C/N为8～ 12,DO浓度约6.5 ～ 7.0 mg/L.在这些培养条件下菌株NO3--N去除率可增至90％以上.菌株RWX31的NO3--N去除能力高于以往报道的反硝化菌株,是一株具有实际应用价值和潜力的菌株.     

降解菌S113对甲磺隆污染土壤生物修复作用的研究

在室内条件下,研究了降解菌S113(Methylopila sp.)对甲磺隆污染土壤的修复作用。S113能够以甲磺隆为唯一碳源生长,72h对50mgL-1甲磺隆的降解率达98.38%。投加降解菌S113可显著提高土壤中甲磺隆的降解速率。当甲磺隆浓度为10mgkg-1干土,S113接种量为108个g-1土时,第30天土壤中甲磺隆降解率为76.9%,对照土壤中甲磺隆降解率仅为11.9%。S113降解甲磺隆的速率和接种量呈正相关,当接种量减少为105个g-1干土时,降解菌对甲磺隆的降解作用微弱。在土壤中甲磺隆浓度较低的条件下,S113的降解效果显著,而当土壤中甲磺隆浓度达到50mgkg-1时,甲磺隆降解率仅为39.6%。S113降解土壤中甲磺隆的最适温度为30℃,第30天的降解率可达75.9%。当温度为25℃、20℃时,第30天甲磺隆降解率仅为53.5%和23.9%。S113菌剂灌根,能不同程度地缓解土壤中浓度为40、80μgkg-1的甲磺隆对玉米生长的抑制作用,但当甲磺隆浓度增加到120μgkg-1时,接种S113对药害解除作用不显著。结果表明,人工接种降解菌S113,能有效去除土壤中甲磺隆残留。     

尿素与除草剂甲基二磺隆复合处理对紫苏生理特性和产量的影响

为探讨尿素与甲基二磺隆对紫苏光合特性指标和籽粒产量的影响,本试验研究了适宜紫苏生长的最佳除草、施肥条件,对六叶期紫苏幼苗先后喷施尿素(0、1、2、4、8 g·L-1)和甲基二磺隆(0、0.175、0.35、0.7、1.4 mL·L-1)处理.结果表明,甲基二磺隆显著降低紫苏叶片的叶绿素含量指数,净光合速率和气孔导度也均不同程度降低,胞间CO2浓度升高,说明甲基二磺隆降低了紫苏的光合作用;叶绿素荧光分析显示,除草剂甲基二磺隆显著降低了光化学荧光淬灭系数、PSⅡ最大光化学效率、PSⅡ潜在活性及PSⅡ实际光化学效率,而非光化学淬灭系数则呈上升趋势.表明紫苏在甲基二磺隆处理下发生了光抑制,同时叶绿体的PSⅡ正常功能受阻;8 g·L-1的尿素处理效果相同;而1 ～4g·L-1浓度的尿素处理则效果相反.1 ～4 g·L-1的尿素和不同浓度的甲基二磺隆先后处理,比单用甲基二磺隆处理效果好,先施4 g·L-1的尿素,后施0.7 mL·L-1甲基二磺隆为最佳处理方案,能显著提高紫苏的光合速率,并使其光系统Ⅱ维持较高的光化学效率.该施药模式可为紫苏田平衡除草施肥和安全高产提供理论基础.     

一株苯酚降解菌的筛选、鉴定及其降解特性

本研究采用逐量分批驯化的方法,从造纸废水中分离得到一株能够以苯酚为唯一碳源生长的苯酚降解菌株F5-1。经形态观察、生理生化特性鉴定及16S rDNA序列分析,将该菌株鉴定为克雷伯菌（Klebsiella sp.）。该菌株能够在7h时完全降解初始浓度为100mg/L的苯酚,降解苯酚主要发生在生长对数期;在pH5.0～9.0,NaCl浓度0～80g/L,温度20～40℃范围内,菌株F5-1均可有效降解初始浓度为100～1200mg/L的苯酚;能够耐受的最大苯酚浓度为1500mg/L。本研究结果表明,F5-1菌株对处理环境条件复杂的含酚废水具有潜在的应用前景。     

苯磺隆降解菌的分离鉴定和特性研究

为解决苯磺隆残留问题,本试验利用富集驯化培养分离法,从连续多年使用苯磺隆的田间土壤中,分离筛出一株能以苯磺隆为唯一碳源、氮源生长的降解菌。通过形态学、生理生化测定及16S r DNA序列系统发育分析,鉴定该菌株为产碱杆菌。抗生素敏感试验和底物敏感试验表明:降解菌株BHL对试验浓度范围内的所有供试抗生素都表现为敏感,其中对硫酸阿米卡星最为敏感;菌株BHL可以很好的利用试验所用磺酰脲类除草剂和有机磷农药,同时还可以利用部分芳香族化合物。本研究为功能农药残留降解菌的研究提供了理论基础。     

两株蜡状芽孢杆菌对毒死蜱的降解动力学研究

利用微生物消除农药污染是一项安全、经济、有效的方法,降解动力学模型的构建有助于理解污染物的生物降解行为和估测系统中特征污染物的浓度变化,菌株对高浓度污染物的降解效果是降解菌在受污染水体中实际应用的关键。本研究采用基础培养基中定量添加毒死蜱和定时取样分析毒死蜱残留浓度的方法,探讨两株蜡状芽孢杆菌(HY-1和HY-2)的接种体培养时间、接种量和降解菌对毒死蜱的降解动力学,同时研究了降解菌对高浓度毒死蜱的降解率。结果表明:HY-1和HY-2最适接种体培养时间分别为10 h和19 h,接种体培养时间对菌株降解毒死蜱的影响较大。两菌株最适接菌量为8%(v/v),接种量从4%增至8%时,接种量对HY-1降解毒死蜱的影响大于HY-2。当毒死蜱的初始浓度为40 mg.L 1、80 mg.L 1、100 mg.L 1和120 mg.L 1时,一级动力学方程ln(C0/Ct)=kt可以用来拟合两菌株对毒死蜱的降解动力学及确定降解动力学参数,当毒死蜱初始浓度再次增加时,仅HY-2对毒死蜱的降解符合一级动力学方程。当毒死蜱初始浓度为40~120 mg.L 1时,菌株HY-1对毒死蜱的降解速率常数分布在0.013 5~0.015 7;当毒死蜱初始浓度为40~200 mg.L 1时,菌株HY-2的降解速率常数分布在0.008 0~0.015 3。菌株HY-2比HY-1可以在较高的毒死蜱浓度下发挥降解作用,且降解率较高。因此,两菌株在毒死蜱污染水体的净化去毒方面具有重要意义。     

人工湿地高效好氧反硝化菌的分离鉴定及反硝化特性研究

从增氧型复合垂直流人工湿地中采集样品,利用间歇曝气法富集好氧反硝化菌,并进行分离纯化,共得到10株好氧反硝化菌。其中编号为B13的菌株在初始硝态氮含量为277.23mg·L-1、碳氮比为5的条件下,24h的硝态氮去除率达92.80%,亚硝态氮积累只有12.57mg·L-1,脱氮速率达到20.58mg·L-·1h-1。16S rDNA序列分析表明,该菌与Pseudomonas stutzeri同源性达100%。选用四因素三水平L（934）正交试验表设计实验,通过测定对硝态氮去除能力和亚硝态氮的积累量,研究碳源、碳氮比（C/N）、pH以及溶解氧含量（DO）4种不同因素对B13号菌株好氧反硝化性能的影响。结果表明,该菌株对硝态氮的去除率最大可达99.88%,几乎没有亚硝态氮积累。对硝态氮去除率影响最大的因素为碳氮比,其次为pH,溶解氧含量和碳源。对应的最优条件是碳源为葡萄糖,碳氮比为10,pH为9,溶解氧含量为1.84～3.57mg·L-1。     

水稻根际耐镉细菌碳源代谢功能分析

为探明前期分离得到的3株水稻根际耐镉细菌碳源代谢特性,在进行生理生化鉴定的基础上,采用BIOLOG ECO微平板法,分析了3株细菌(菌株A、菌株B和菌株C)的碳源代谢功能。生理生化试验结果表明,3株菌均属于革兰氏阴性细菌,且均具有极生鞭毛,菌株C的生理生化鉴定为铜绿假单胞菌,菌株A与菌株B为假单胞菌属的其他种,结果与之前的分子生物学鉴定结果一致。BIOLOG分析结果表明,3株菌株在培养72 h的AWCD(平均颜色变化率)均接近最大值,在培养24 h时的AWCD存在显著差异,这种差异主要体现在对氨基酸的利用上。在对提供的31种单一碳源利用上,3株菌对N-乙酰-D-葡萄糖胺、L-精氨酸、L-天冬酰胺、甲叉丁二酸、腐胺、4-羟基苯甲酸、丙酮酸甲酯、吐温-40和吐温-80的利用率均较高,且对L-精氨酸、甲叉丁二酸、丙酮酸甲酯的利用率存在显著差异。本研究结果对深入了解耐镉菌株增殖所需要的碳源以及将来优化耐镉细菌最适培养基提供了理论依据,也为构建相应的基因工程菌提供了微生物资源。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

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.     

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.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.