聚羟基烷酸合成菌的分离·鉴定及其生长特性研究

［目的］获取性状优良的聚羟基烷酸（PHAs）合成菌。［方法］以东湖底泥、山坡裸地土、肥沃菜园土和油脂浸润土为初始样品,经富集、分离纯化、苏丹黑B染色、红外光谱及气相色谱定性定量分析筛选出具PHAs合成能力的细菌菌株。［结果］苏丹黑B染色结果表明,在分离出的12株细菌中有3株细菌具有PHAs合成能力,其编号分别是Zj5、Zj8和Zj9。3株细菌均在1 741 cm-1附近呈现吸收峰,菌株Zj8和Zj9的红外谱图相似。菌株Zj5、Zj8和Zj9的PHAs含量分别为146.85、0.65和3.48 mg/L,菌株Zj5被初步鉴定为假单胞菌属细菌。菌株Zj5在pH值为5.0-9.0的环境中均能生长,其生长的最适pH值为7.6;在25-35 ℃下均能正常生长,其最适培养温度和通气量分别为30 ℃和100 ml。［结论］ 菌株Zj5、Zj8和Zj9有PHAs合成能力且菌株Zj5的合成能力最强。     

产油微生物的筛选及其产油率测定

为寻求可再生、环境友好且经济可行的化石能源替代燃料,采用苏丹黑B和尼罗红染色法及甲醇-氯仿提取法对平顶山各地不同生境富含油脂土壤中的高产油脂微生物进行分离筛选。结果表明:试验分离到2株产油菌株PDS1和PDS2。其中,产油细菌PDS1为革兰氏阴性菌,产油率为29.47%;产油细菌PDS2为革兰氏阳性菌,产油率为23.57%。     

Do camels (<Emphasis Type="Italic">Camelus dromedarius</Emphasis>) play an epidemiological role in the spread of Shiga Toxin producing <Emphasis Type="Italic">Escherichia coli</Emphasis> (STEC) infection?

In the present work, faecal and serum samples from 400 camels were investigated for the presence of Shiga Toxin producing E.coli (STEC) and Anti-Shiga Toxin (Anti-Stx) antibodies, respectively. The used samples were obtained from adult male camels of five east African countries (Egypt, Somalia, Djibouti, Kenya and Sudan) between the years 2002-2004. One E.coli isolate per camel was randomly selected to be cultured on Gassner, Chromocult and sorbit agar for the detection of O157:H7 strains. In the same time, a Stx-specific PCR screening was performed for the isolates using the shiga toxin specific primers Mk1-Mk2. Vero cells were also used for shiga toxin neutralization assay. None of the investigated isolates reacted positively with the Stx-specific primers. Also, none of the studied sera could neutralize the Stx on tissue culture. The obtained results indicate that camels do not play any significant epidemiological role in STEC infection and transmission. The possible reasons for the absence of STEC in the investigated samples are discussed in brief.     

高效液相色谱法快速检测食品中苏丹红的含量

[目的]建立快速检测食品中苏丹红（苏丹红I、Ⅱ、Ⅲ、IV）含量的高效液相色谱法,简化样品的前处理,降低成本,缩短仪器检测时间。[方法]选用Athena C18-XDB色谱柱（4．6mm×150．0mm,3．5um）,以乙腈水溶液和乙腈丙酮溶液为流动相进行等度洗脱,通过二极管阵列检测器检测食品中苏丹红。[结果]该方法检测线性良好,相关系数R≥0．9991,检出限为0．01mg／L,相对标准偏差（n=10）为0．9％～2．0％,回收率为90％～96％。[结论]该法具有较高的准确度和精密度,适用于食品中苏丹红含量的测定。     

卫星搭载对高丹草农艺性状的影响研究

[目的]探索卫星搭载对"先锋"高丹草农艺性状的影响。[方法]将搭载后的"先锋"和未搭载的作比较试验,并对其农艺性状进行比较评价。[结果]与未搭载处理相比,搭载后物候期变化不明显,但在生长速度、株高、节径、分蘖数、叶面积、叶片数、茎叶比、产量等农艺性状上都发生了变化,特别是分蘖数和叶片数发生了显著变异,表现为"多蘖型"和"丰叶型"。通过茎段扦插和宿根繁殖可以保持突变性状,但无法将其用于新品种选育。[结论]卫星搭载后,"先锋"高丹草的株高和产量发生了变化,但有益突变性状的有性稳定遗传是下一步研究的重点。     

抗叶斑病苏丹草杂交制种技术及其种质创新

通过高粱胞质型不育系“2 0 98A”(♀ )和抗叶斑病苏丹草恢复系“2 0 98”( )的分期播种试验 ,探明了抗叶斑病杂交制种中父母本花期相遇且制种产量高的适宜播期为 4月 2 5日至 5月 10日。通过苏丹草与拟高粱远缘杂交 ,成功获得了F1代杂种 ,经鉴定为高抗叶斑病型 ,系苏丹草抗叶斑病育种的创新种质资源。     

Importance of forest buffers for preserving soil carbon and nutrient stocks in farmed landscapes along two river sites in the savannas of the Volta basin,Ghana

Understanding the impacts of agricultural land use is desired for proper management of riparian forests buffers (RFs) in savannas. In this light, we analyzed the relationship between woody plant diversity and soil properties of RFs in farmlands (FAs) and protected areas (PAs) along Afram (Guinean zone) and Tankwidi (Sudanian zone) Rivers located within the Volta sub-basin of Ghana. ALOS-AVNIR imageries were used to map RFs to facilitate sampling of soil and woody vegetation (dbh ≥5?cm) using stratified randomized design (72 plots; size: 500?m² each) for the analysis of soil physical and chemical properties and Shannon-Wiener plant species diversity. Although the fractions of sand, silt, and clay varied between the PAs and FAs, they were predominantly categorized as sandy loam. Along the Afram River, there were no significant differences in the concentrations and nutrient stocks of soil C, N, P, and K as well as the pH, moisture content, and bulk density between PA and FA. For the Tankwidi River, the concentrations and nutrient stocks of C and K significantly decreased from PA to FA while N, P, pH, bulk density, and moisture content were not different. Of the soil attributes measured C, N, P, pH, ground slope, and soil moisture had significant relationships with the diversity and density of the riparian woody plants. Controlling agricultural activities in riparian forests could preserve soil properties similar to that found in protected areas.     

Evaluation of Chemical Extraction Methods for Determining Plant-Available Potassium in Some Soils of West Bengal,India

The effectiveness of eight chemical extraction methods was evaluated on 15 Indian soils for the prediction of plant-available potassium (K⁺) to Sudan grass (Sorghum vulgare var. sudanensis) grown in modified Neubauer technique. Average amounts of soil K⁺ extracted were in descending order: Morgan’s reagent > 0.5 M sodium bicarbonate (NaHCO₃) > neutral 1N ammonium acetate (NH₄OAc) > 1N nitric acid (HNO₃) > 0.02 M calcium chloride (CaCl₂) > 0.1N HNO₃ > Bray and Kurtz No.1> distilled water. The highest simple correlation with plant K⁺ uptake was obtained with NH₄OAc-K⁺ (r = 0.866**) and the lowest with CaCl₂-K⁺ (r = 0.45*). To develop the predictive models using stepwise regression, plant K⁺ uptake was used as the dependent variable and the extractable soil K⁺, pH, sand, silt and organic carbon (C) contents as the independent variables. Based on the final R², the NH₄OAc model was found to be the best predictor of plant-available K⁺ in the soils when used along with sand and organic C.     

喷施羧甲基纤维素铵对土壤水热效应及饲用苏丹草根系和产量的影响

【目的】研究喷施羧甲基纤维素铵（CMC-NH₄）对土壤含水量和温度及苏丹草根系和产量的影响，为解决宁夏引黄灌区热量紧缺问题、保障后茬作物稳产增产提供技术支撑。【方法】在宁夏引黄灌区，以小麦收获后复种的苏丹草为材料，采用大田试验，设置喷施0 kg/hm² (CK)、50 kg/hm² (T1)、100 kg/hm² (T2)、200 kg/hm² (T3)和300 kg/hm² (T4) CMC-NH₄ 5个处理，研究喷施CMC-NH₄对土壤含水量和温度，以及苏丹草根系特征、株高和干草产量的影响，并分析了CMC-NH₄喷施量与土壤含水量、温度及苏丹草生长指标和产量间的相关性。【结果】喷施CMC-NH₄处理土壤含水量较对照显著提高2.82%~29.19%(P＜0.05)，且随着CMC-NH₄喷施量的增加而增大。喷施CMC-NH₄处理土壤温度较对照显著提高5.14%~31.82%，且随着CMC-NH₄喷施量的增加而增大。在0~30 cm土层，与对照相比，喷施CMC-NH₄处理苏丹草的根长、根直径、根表面积和根体积分别显著提高16.35%~ 65.52%，7.69%~30.77%，42.40%~93.85%和120.76%~229.90%；0~10 cm土层苏丹草根长、根直径、根表面积和根体积占0~30 cm土层的比例均最高，根长、根直径、根表面积和根体积分别较对照提高了21.21%~74.76%，9.68%~58.06%，61.95%~136.13%和122.60%~273.18%。与对照相比，喷施CMC-NH₄处理苏丹草0~1.0 mm径级根长、根表面积和根体积显著提高，其中以0.6~1.0 mm径级根系增加幅度较大。喷施CMC-NH₄处理苏丹草株高和干草产量较对照分别显著增加了9.34%~22.52%和55.50%~110.55%。相关性分析结果表明，CMC-NH₄喷施量与土壤含水量、温度及苏丹草的根直径、体积和干草产量呈极显著正相关，与根长和根表面积呈显著正相关。【结论】在宁夏引黄灌区农田喷施CMC-NH₄能够改善土壤水温状况，促进苏丹草根系生长，提高干草产量，当CMC-NH₄喷施量为200 kg/hm²时效果最佳。