水分和氧气对毛萼田菁茎瘤固氮作用的影响

水分剥夺引起毛萼田菁（Ｓｅｓｂａｎｉａｒｏｓｔｒａｔａ）茎瘤固氮活性的下降；水分剥夺还导致茎瘤类菌体固氮的最适Ｏ２分压（ｐＯ２）和呼吸强度的下降及茎瘤豆血红蛋白和细胞质可溶性蛋白含量的下降。测定水分剥夺的茎瘤在不同ｐＯ２下的固氮活性和茎瘤组织切片的显微观察，支持水分胁迫可使Ｏ２扩散阻力增大这一观点。测定不同ｐＯ２下离体茎瘤固氮活性以ｐＯ２为６０％最高；当把茎瘤切碎后，茎瘤皮层的扩散屏障作用降低或失去，最适ｐＯ２降至４０％，说明Ｏ２是茎瘤固氮作用的限制因子。     

暹罗鱼腥藻氢代谢的调节

暹罗鱼腥藻（Ａｎａｂａｅｎａｓｉａｍｅｍｓｉｓ）能代谢分子氢，其固氮酶和氢酶的放氢和吸氢均受其生长环境因子的影响。ＣＯ２对暹罗鱼腥藻之固氮酶的放氢和氢酶的放氢及吸氢显示不同程度的促进作用。在含５％ＣＯ２的空气条件下生长，藻细胞的氢酶放氢和吸氢活位分别为空气条件下的２．５倍和１．３倍；固氮酶的放氢活性为９６ｎｍｏｌＨ２ｍｇ－１ｃｈｌ－１ｈ－１，而在空气中生长的细胞则检测不出该活性，培养基中加１０ｍｍｏｌ／ＬＫＮＯ３和／或１０ｍｍｏｌ／ＬＮａＮＯ２，对其氢酶放氢活性影响不大，但其需氧吸氢和固氮酶的放氢均明显受到抑制。ＤＣＭＵ和Ｋ３Ｆｅ（ＣＮ）６等抑制剂对氢酶活性有不同程度的影响，一些金属离子对氢酶放氢有刺激作用，其中尤以Ｎｉ２＋和Ｍｏ２＋明显。     

菠菜（Spinacia oleracea）硝酸盐含量的控制和预测的研究

建立了菜园系统中施氮量ρＡ（Ｎ）土壤水分ｗ（Ｈ２Ｏ）（以占田间最大持水量的百分数表示）土壤肥力ｗ（ＲＡＨＮ）（以土壤还原碱解Ｎ（ＲＡＨＮ）水平表示）３因素影响菠菜植株ＮＯ３－Ｎ含量（ｗ（ＮＯ３－Ｎ）的三元二次数学模型，模型分析和盆栽，微区及大田验证试验结果表明：３因素对菠菜植株ｗ（ＮＯ３－Ｎ）影响的顺序是：ρＡ（Ｎ）〉ｗ（ＲＡＨＮ）〉ｗ（Ｈ２Ｏ），既能使菠菜高产，又能使植株ｗ（ＮＯ３－Ｎ）达到国颁     

H2O2对抗旱性不同玉米品种愈伤组织抗氧化系统的影响

两个玉米品种愈伤组织经１０－４ｍｏｌＬ－１、１０－３ｍｏｌＬ－１和１０－２ｍｏｌＬ－１Ｈ２Ｏ２处理３ｈ后,电解质泄漏率加大;Ｈ２Ｏ２和ＭＤＡ含量增加;ＡｓＡ和ＣＡＲ含量的减少．１０－４ｍｏｌＬ－１的Ｈ２Ｏ２处理对愈伤组织产生的氧化伤害较小．抗旱性较强品种ＰＡＮ６０４３愈伤组织的抗氧化酶（ＳＯＤ、ＰＯＤ、ＡＰ和ＧＲ）活性高于抗旱性较弱品种ＳＣ７０１,ＡｓＡ和ＣＡＲ含量的下降程度低于ＳＣ７０１．ＰＡＮ６０４３愈伤组织具有较强的抗Ｈ２Ｏ２能力,与含高活力抗氧化系统密切相关     

胡椒养分含量状况的研究

胡椒大、中量元素的含量在不同树龄中有所不同，幼龄期以氮最高，其Ｎ：Ｐ２Ｏ３：Ｋ２Ｏ：Ｃａ：Ｍｇ为１：０．１５：０．５３－０．９：０．２２－０．３８：０．１５－０．３０；成年龄则以Ｋ２Ｏ最高，Ｎ：Ｐ２Ｏ３：Ｋ２Ｏ：Ｃａ：Ｍｇ为１：０．１３：１．３２：０．４４：０．１６．在不施微肥的情况下，胡椒叶片缺Ｂ、Ｍｏ、Ｚｎ．成年龄胡椒各养分含量都是从萌芽期（收获后）开始，随生育期的进展而增加，到果实成熟期下降．一株中产胡椒Ｎ、Ｐ２Ｏ５、Ｋ２Ｏ总吸收量为２８２．４ｇ，其比例为１：０．１９：０．９．     

不同菌源的微生物对邻苯二甲酸二甲酯生物降解性的比较

从处理石化厂废水的活性污泥中分离出１ 株邻苯二甲酸酯降解菌 Ｆ Ｓ１（ 荧光假单胞菌 Ｐｓｅｕｄｏｍｏｎａｓｆｌｕｏｒｅｓｃｅｎｓ Ｆ Ｓ１） ,从处理焦化厂废水的活性污泥中分离出２ 株邻苯二甲酸酯降解菌 Ｆ Ｓ２（ 铜绿假单胞菌 Ｐｓｅｕｄｏｍｏｎａｓａｅｒｕｇｉｎａｓａ Ｆ Ｓ２） 和 Ｆ Ｓ３（ 短杆菌 Ｂｒｅｖｉｂａｃｔｅｒｉｕｍ ｓｐ ． Ｆ Ｓ３） ． 研究了邻苯二甲酸酯降解菌 Ｆ Ｓ１ , Ｆ Ｓ２ 和 Ｆ Ｓ３ 对邻苯二甲酸二甲酯（ Ｄ Ｍ Ｐ） 的最适降解条件,比较了其降解特性． Ｆ Ｓ１ 、 Ｆ Ｓ２ 和 Ｆ Ｓ３ 最适酸度分别为ｐ Ｈ６ ．５ ～８ ．０ 、ｐ Ｈ７ ．０ ～８ ．０ 和ｐ Ｈ７ ．０ ～８ ．０ ,温度为２０ ～３５ ℃、１５ ～３５ ℃和１５ ～３５ ℃．邻苯二甲酸酯降解菌 Ｆ Ｓ１ 、 Ｆ Ｓ２ 和 Ｆ Ｓ３ 对邻苯二甲酸二甲酯的降解的半寿期： Ｆ Ｓ１ ＜ Ｆ Ｓ２ ＜ Ｆ Ｓ３ ,邻苯二甲酸酯降解菌 Ｆ Ｓ１ 是一株高效的邻苯二甲酸二甲酯降解菌     

微生物降解蔬菜残留农药研究

从富集培养物中筛选到以甲胺磷为唯一碳源生长的菌株ＮＭＪ５和以乐果为唯一碳源生长的菌株ＮＭＬ３，经鉴定分别为芽孢杆菌属（Ｂａｃｉｌｕｓｓｐ．）和假单胞菌属（Ｐｓｅｕｄｏｍｏｎａｓｓｐ．）．它们利用甲胺磷、乐果生长的最适条件及在无机盐培养基中农药最大耐受浓度分别为ｐＨ７．５，ｔ＝３５℃，ρ＝１０００ｍｇ／Ｌ和ｐＨ７．５，ｔ＝３０℃，ρ＝２０００ｍｇ／Ｌ．在无碳基础培养基内单菌株培养８ｄ，５２４ｍｇ／Ｌ的甲胺磷好气降解４２．５％，厌气降解３５．９％，２５０ｍｇ／Ｌ的乐果好气降解５０．２％，厌气降解１６．４％．小区试验表明，ＮＭＪ５、ＮＭＬ３的菌液制剂对普通白菜的变种南农矮脚黄（Ｂｒａｓｉｃａｃａｍｐｅｓｔｒｉｓｓｐ．ｃｈｉｎｅｎｓｉｓＬ．ｖａｒ．ｃｏｍｍｕｎｉｓＴｓｅｎｅｔＬｅｅ）中残留的甲胺磷、乐果有明显的去除作用．     

游蛇科4种的核型比较

以骨髓细胞直接制备染色体标本，分析了游蛇属（Ｎａｏｔｒｉｘ）３种和链蛇属（Ｄｉｎｏｄｏｎ）１种蛇的核型．草游蛇（Ｎ．ｓｔｏｌａｔａ）２ｎ＝３６，１８（１５Ｍ＋１ＳＴ＋２Ｔ）·１８ｍ（♀）．渔游蛇（Ｎ．Ｐｉｓｃａｔｏｒ）２ｎ＝４０，１６（１０Ｍ＋１ＳＭ＋３ＳＴ＋２Ｔ）·２４ｍ（♀）．乌游蛇（Ｎ．ｐ．ｐｅｒｃａｒｉｎａｔａ）２ｎ＝４０，１８（８Ｍ十２ＳＭ＋８Ｔ）·２２ｍ（♂）．赤链蛇（Ｄ．ｒｕｆｏｚｏｎａｔｕｍ）２ｎ＝４６，２０（１Ｍ＋３ＳＭ＋１６Ｔ）·２６ｍ（♀）．草游蛇和渔游蛇的Ｎｏｓ，赤链蛇的Ｎｏ３为ＺＺ／ＺＷ型性染色体．草游蛇Ｚ染色体为Ｍ型，Ｗ染色体为ＳＴ型；渔游蛇Ｚ为ＳＭ型，Ｗ也是ＳＴ型；赤链蛇Ｚ为Ｍ型，Ｗ为ＳＭ型．三者Ｚ均略大于Ｗ．草游蛇和渔游蛇Ｎｏ４长臂末端有时可见随体．对游蛇属、链蛇属以及游蛇亚科（Ｃｏｌｕｂｒｉｎａｅ）已知各属种的核型进行了比较和讨论．     

硫化亚铁处理含砷废水中砷的形态变化

本文对用硫化亚铁处理含砷废水时，在气相、液相和固相中砷的形态进行了研究结果表明，在气相中无ＡａＨ３，但在Ａｓ（Ｖ）废水的液相中有Ａｓ（Ｖ）和Ａｓ（Ⅲ）共同存在，在固相中有Ａｓ（０），ＦｅＡｓＯ４（ＦｅＡｓＯ３），Ａｓ２Ｓ３（Ａｓ２Ｓ５）和吸附砷，砷的形态变化表明，硫化亚铁处理含砷废水能取得良好的效果，是沉淀、沉淀转化、氧化还原、吸附共沉淀和中和五种反应共同作用的结果。     

邻苯二酚1,2-双加氧酶(C12O)基因的定位、克隆和表达

射性同位素标记ｔｆｄＣ基因片段作探针,Ｓｏｕｔｈｅｒｎｂｌｏｔ杂交定位Ｌ１菌株的邻苯二酚１,２双加氧酶基因位于ＰｓｔⅠ的Ｉ片段和ＢａｍＨⅠ的Ｍ和Ｎ片段．低熔点琼脂糖回收ＰｓｔⅠ的Ｉ段,直接克隆至表达载体ｐＫＴ２３０上,获得重组子ｐＫＴ２３０ｐ．重组子转化不具开环酶活性的甲胺磷降解菌Ｐ２,获得高效的Ｃ１２Ｏ酶活     

White locoweed toxicity is facilitated by a fungal endophyte and nitrogen-fixing bacteria

Mutualistic interactions with fungal endophytes and dinitrogen-fixing bacteria are known to exert key biological influences on the host plant. The influence of a fungal endophyte alkaloid on the toxicity of a plant has been documented in Oxytropis sericea. Oxytropis sericea is a perennial legume responsible for livestock poisoning in western North America. Livestock poisoning is attributed to the alkaloid swainsonine, which is synthesized inside the plant by the fungal endophyte Embellisia sp. In this study, the ability of Oxytropis sericea to form a dinitrogen-fixing symbiosis with Rhizobium and the effects of this symbiosis on the production of swainsonine by Embellisia sp. were evaluated in a greenhouse environment. Seeds of O. sericea were grown in plastic containers. Twenty-week-old O. sericea seedlings were inoculated with four strains of Rhizobium. Twenty weeks after inoculation, plant growth and root nodulation by Rhizobium were measured. Dinitrogen fixation was confirmed using an acetylene reduction assay (ARA) on excised root nodules. Dry leaves were analyzed for swainsonine content. A second set of plants was treated with fungicide to evaluate the effect of reduced fungal endophyte infection on plant growth and swainsonine production. All inoculated plants produced indeterminate nodules. The ARA indicated that 98% of the excised nodules were fixing dinitrogen. Rhizobium-treated plants had greater swainsonine concentrations than the non-inoculated controls. Plants that established from seeds treated with fungicide had lower biomass than non-fungicide-treated controls and plants treated with foliar fungicide. Plants treated with foliar fungicide and the controls had greater swainsonine concentrations than the plants that received seed fungicide. This greenhouse study is the first report of nodulation and dinitrogen fixation in O. sericea. It also demonstrates that dinitrogen fixation increases the production of swainsonine in O. sericea plants infected with Embellisia sp. Results from this study suggest that dinitrogen fixation affects swainsonine production and has the potential to support the symbiosis between Embellisia sp. and O. sericea when soil nitrogen is limited. Oxytropis sericea competitiveness appears to be facilitated by an ability to simultaneously associate with Rhizobium and a fungal symbiont.     

玉米-花生混作系统中的氮铁营养效应

采用盆栽试验的方法研究了不同施氮水平和种间相互作用对花生铁营养、根瘤固氮能力以及系统氮营养的影响。结果表明,在本试验种植密度下,施氮水平和种植方式对下针期单株花生生物量无显著影响。在不同施氮水平下,玉米-花生混作不仅均显著改善了花生铁营养,而且玉米对氮素的大量吸收显著降低了混作花生根际土壤硝态氮的质量分数,从而使得花生根瘤数增加,根瘤固氮酶活性增强。混作花生铁营养受混作玉米氮营养及作物发育状况的影响较大,并且下针期花生固氮酶活性受施氮抑制及花生铁营养改善的促进。这说明,根际土壤硝态氮的质量分数的降低和花生铁营养的改善是石灰性土壤上花生固氮能力增强的关键因素,而花生生物固氮作用的增强是该混作系统体现氮营养优势的主要原因。     

硝酸根对罗丹明B光解的敏化作用

研究了紫外光照射下，KNO3对罗丹明B光解的敏化作用．结果表明，KNO3的加入可以显著提高罗丹明B的光降解率，反应液的酸度愈强愈有利于反应的进行，KNO3不仅对罗丹明B的降解有敏化作用，而且还能够直接提供氧化罗丹明B所需要的氧。     

一株花生根际促生菌的筛选鉴定及其特性研究

从种植于红壤的健康花生根际,筛选出7株产吲哚乙酸(IAA)菌株,以菌株L4合成IAA的能力最强,培养24 h时IAA产生量达135.67μg.mL-1,且菌株L4具有解磷能力。通过菌株形态、生理生化特征测定及16SrRNA的保守序列鉴定,初步确定菌株L4为氯酚节杆菌(Arthrobacter chlorophenolicus),其GenBank登录号为JQ277449。菌株生长和发酵条件试验结果表明,菌株L4生长和分泌IAA的最佳培养条件并不完全一致,既能促进菌株生长又能合成较多IAA的最佳培养条件是初始pH值为5～6,装液量为50 mL.(250 mL)-1,30℃摇床培养24 h;促进菌株生长的最佳碳、氮源分别是麦芽糖和酵母粉,而提高IAA产生量的最佳碳源是木糖,最佳氮源是KNO3。     

Nitrogen accretion,and the nature and possible significance of N2 fixation (Acetylene reduction) in a Nova Scotian Spartina alterniflora stand

Total aboveground nitrogen accretion through the 1975 growing season at a short Spartina alterniflora stand was estimated as 78 kg N ha^-1, compared to estimated N₂ fixation on the mud surface of 22 kg N ha^-1 and subsurface N₂ fixation of 93 kg N ha^-1. Subsurface N accretion was estimated to be of the order of 77 kg N ha^-1. Mudsurface ARA (acetylene-reducing activity) exhibited a pronounced mid-season maximum, while subsurface ARA exhibited a general trend of increase from May to September, and then a decline as a function of falling temperature. Various experiments suggested that mud-surface ARA was associated largely with non-heterocystous blue-green algae and photosynthetic bacteria, while subsurface ARA was associated mainly with vital activity of S. alterniflora. Counts of various groups of bacteria indicated an enrichment of anaerobic (glucose-utilizing) and microaerophilic (malateutilizing) N₂-fixing bacteria in the rhizosphere in comparison to non-rhizosphere soil. Treatment of roots with chloramine-t for 2 h reduced total numbers (plate count), anaerobic N₂ fixers, and microaerophilic N₂ fixers by factors of 357, 172, and 22, respectively, suggesting a relative enrichment of microaerophiles in the interior or endorhizosphere of the roots. ARA of excised roots was correlated with ¹⁴C-activity for roots from a plant previously exposed to ¹⁴CO₂, and with branching and age of the roots.     

Hydrogen production by nitrogenase as a potential crop rotation benefit

Both climate change and the adverse effects of chemical use on human and environmental health are recognized as serious issues of global concern. Nowhere is this more apparent than in the agricultural sector where release of greenhouse gases such as carbon dioxide, nitrous oxide and methane continues to be problematic and where use of nitrogen fertilizer is responsible for negative impacts on both human populations and ecosystems. The manipulation of biological nitrogen fixation (BNF) could help alleviate part of the difficulty by decreasing the need for nitrogen fertilizers, which require huge quantities of fossil fuel to produce and contribute to the release of nitrous oxide from soil as well as being responsible for the contamination of drinking water systems and natural habitats. BNF is performed by a variety of microorganisms. One of the most studied examples is the BNF carried out by rhizobial bacteria in symbiosis with their plant hosts such as pea and soybean. Hydrogen gas is an energy-rich, obligate by-product of BNF. Legume symbioses with rhizobia lacking hydrogenase enzymes (which can recycle hydrogen) have traditionally been viewed as energetically inefficient. However, recent studies suggest hydrogen release to soil may be beneficial, increasing soil carbon sequestration and promoting growth of hydrogen-oxidizing bacteria beneficial to plant growth; the alleged superiority of symbiotic performance in rhizobia possessing functional hydrogenases (HUP⁺) over those rhizobia without functional hydrogenases (HUP⁻) has also not been conclusively shown. The structure of the iron-molybdenum cofactor or FeMo-co of nitrogenase (the active site of the enzyme) has been elucidated through X-ray crystallography but the mechanism of nitrogen fixation remains unknown. However, studies of effects of hydrogen production on BNF have revealed potential candidate intermediates involved in the nitrogenase reaction pathway and have also shown the role of hydrogen as a competitive inhibitor of N₂, with hydrogen now considered to be the primary regulator of the nitrogenase electron allocation coefficient. The regulation of oxygen levels within legume root nodules is also being investigated; nitrogen fixation is energetically expensive, requiring a plentiful oxygen supply but too high an oxygen concentration can irreversibly damage nitrogenase, so some regulation is needed. There is evidence from gas diffusion studies suggesting the presence of a diffusion barrier in nodules; leghaemoglobin is another potential O₂ regulator. Possible functions of hydrogenases include hydrogen recycling, protection of nitrogenase from damaging O₂ levels and prevention of inhibitory H₂ accumulation; there is evidence for H₂ recycling only in studies where H₂ uptake has been strongly coupled to ATP production and where this is not the case, it is believed that the hydrogenase acts as an O₂ scavenger, lowering O₂ concentrations. The distribution of hydrogenases in temperate legumes has been found to be narrow and root and shoot grafting experiments suggest the host plant may exert some influence on the expression of hydrogenase (HUP) genes in rhizobia that possess them. Many still believe that HUP⁺ rhizobia are superior in performance to HUP⁻ species; to this end, many attempts to increase the relative efficiency of nitrogenase through the introduction of HUP genes into the plasmids or chromosomes of HUP⁻ rhizobia have been carried out and some have met with success but many other studies have not revealed an increase in symbiotic performance after successful insertion of HUP genes so the role of HUP in increasing parameters such as N₂ fixation and plant yield is still unclear. One advantage of the hydrogen production innate to BNF is that the H₂ evolved can be used to measure N₂ fixation using new open-flow gas chamber techniques seen as superior to the traditional acetylene reduction assay (ARA) conducted in closed chambers, although H₂ cannot be used for field studies yet as the ARA can. However, the ARA is now believed to be unreliable in field studies and it is recommended that other measures such as dry weight, yield and total nitrogen content are more accurate, especially in determining real food production, particularly in the developing nations. Another potential benefit of H₂ release from root nodules is that it stays in the soil and has been found to be consumed by H₂-oxidizing bacteria, many of which show plant growth–promoting properties such as the inhibition of ethylene biosynthesis in the host plant, leading to root elongation and increased plant growth; they may well be promising as biofertilizers if they can be successfully developed into seed inoculants for non-leguminous crop species, decreasing the need for chemical fertilizers. It has been suggested that rhizobia can produce nitrous oxide through denitrification but this has never been shown; it is possible that hydrogen release may provide more ideal conditions for denitrifying, free-living bacteria and so increase production of nitrous oxide that way and this issue will require more study. However, it seems unlikely that a natural system would release nitrous oxide to the same degree that chemical fertilizers have been shown to do.     

La(NO3)3浸种对盐碱胁迫下红小豆幼苗生长和抗氧化酶活性的影响

采用添加NaCl和Na2CO3模拟盐胁迫和碱胁迫的水培方式,研究了La(NO3),浸种对盐胁迫和碱胁迫下红小豆幼苗生长和抗氧化酶活性的影响.结果表明:(1)与无胁迫对照组相比,盐碱胁迫明显抑制了红小豆幼苗的生长;在Na+质量浓度相同的情况下,碱胁迫对红小豆幼苗生长的影响明显大于盐胁迫;(2)使用La(NO3)3浸种可缓解盐碱胁迫带来的不良影响,使受胁迫红小豆的株高、叶面积、总根长、总根数、叶绿素、根活力、SOD活性、POD活性及CAT活性增加,并显著降低幼苗MDA含量水平,且表现出在盐碱胁迫下变化幅度高于无胁迫处理的现象;(3)在本试验条件下,30 mg·L-1La(NO3)3浸种具有显著促进红小豆根系及地上部分生长的作用.     

植物根瘤内痕量Frankia DNA的提取及鉴定

建立了一种简捷、快速植物根瘤内痕量Frankia DNA的提取方法，即采集自然态下根瘤，剥离瘤瓣，取瘤瓣尖经液氮研主民粉末，以20g/L CTAB（十六烷基三甲基溴化铵）消化胞壁，然后以d=5-10μm的石英粉吸附DNA，再以无菌去离子蒸馏水释放DNA，所获DNA产率及纯度较酚／氯仿法好。经对辽宁沙棘、色赤杨根瘤的瘤内痕量Frankia DNA及体外培养的9种Frankia菌株DNA分纯，并用于酶切及PCR，获满意结果。图3参12     

模拟氮沉降对兴安落叶松林凋落物分解的影响

试验施加NH4NO3、KNO3和NH4Cl3种氮肥,设置对照（N0,0 kg·hm-2·a-1）、低氮（N1,10 kg·hm-2·a-1）、中氮（N2,20kg·hm-2·a-1）、高氮（N3,40 kg·hm-2·a-1）4个施氮水平,通过交互试验,研究模拟N沉降对大兴安岭兴安落叶松（Larix gmelinii）林凋落物分解的影响。结果表明,在兴安落叶松林凋落物分解过程中,叶分解最快,其次是枝,分解最慢的为果,在分解16个月后,枝、叶、果的质量残留率分别为76.68%、47.98%和80.43%,3者异极其显著（p〈0.01）。凋落物叶分解95%所需时间为6.71 a,而枝和果所需时间分别为18.07和18.10 a。在模拟大气氮沉降下凋落物分解过程中,施加KNO3,N2处理下的枝、叶、果的质量残留率极显著低于N3处理（p〈0.01）,显著低于N0和N1处理。施加NH4Cl下,N1处理显著低于N0处理（p〈0.05）。在施加NH4NO3下,N1水平处理下的枝、叶、果的分解速率显著增加（p〈0.05）,但是随着施氮量的增加,分解速率就会减慢,N3处理下,有着明显的抑制作用（p〈0.05）,说明氮沉降对于凋落物分解有着促进作用,但是随着时间和氮沉降量的增加,促进作用延缓甚至是抑制作用。