Physiological and biochemical responses resulting from nitrite accumulation in tomato (Lycopersicon esculentum Mill. cv. Ibiza F1)

The sensitivity of hydroponically cultivated tomato (Lycopersicon esculentum Mill. cv. Ibiza F1) submitted to nitrite treatments (0.25-10mM KNO(2)) for 7d was studied. Increasing nitrite levels in the culture medium led to several disruptions of tomato plants, reflected by reductions of both dry matter per plant, chlorophyll concentrations and the appearance of chlorosis symptoms at the leaf surface. This behaviour was accompanied by stimulation of nitrite, nitrate and ammonia ion accumulation, mainly in roots and old leaves. Higher proteolytic and gaiacol peroxidase (GPX, EC. 1.11.1.7) activities and malonyldialdehyde content were also noted. Protein content of the different plant organs was decreased by nitrite treatment. These physiological and biochemical parameters were chosen as they are stress indicators. Taken together, our data partly explain the harmful effects of nitrite ions, when excessive in the culture medium.     

Destruction of Salmonella typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes in chicken manure by drying and/or gassing with ammonia

Escherichia coli O157:H7 and Listeria monocytogenes were able to grow for a period of 2 days in fresh chicken manure at 20 degrees C with a resulting 1-2 log units increase in CFU; Salmonella typhimurium remained stable. Prolongation of the storage time to 6 days resulted in a 1-2 log decreases of S. typhimurium compared to the initial count and a 3-4 log decrease of E. coli O157:H7; the number of L. monocytogenes did not decrease below the initial. These changes were accompanied by an increase in pH and accumulation of ammonia in the manure. The destruction of the three microorganisms was greatly increased by drying the manure to a moisture content of 10% followed by exposure to ammonia gas in an amount of 1% of the manure wet weight; S. typhimurium and E. coli O157:H7 were reduced by 8 log units, L. monocytogenes by 4.     

小麦,玉米接种耐氨固氮菌试验初步分析

１９８９—１９９２年,在广东省部分县市进行了小麦、王米施用耐氨固氮菌大田对比试验,小麦接种耐氨固氮菌后,接菌区小麦的穗氏、有效穗、每穗粒数均比不接菌区明显增加,株高、成穗率、千粒重比对照略有增加,平均每亩比对照增产１６．７ｋｇ干麦,平均增产率为８．１％。玉米接种耐氨固氮菌后,接菌区玉米的茎粗、收获时的青叶片数、单苞重均比对照区明显增加,秃顶度比对照区明显减小,晒干率：出米率略有增加,平均每亩比对照增产５２．８ｋｇ玉米,平均增产率为１１．８９％。     

Microalgae-based processes for the biodegradation of pretreated piggery wastewaters

The potential and limitations of photosynthetic oxygenation on carbon and nitrogen removal from swine slurry were investigated in batch experiments using Chlorella sorokiniana and an acclimated activated sludge as model microorganisms. While algal-bacterial systems exhibited similar performance than aerated activated sludge in tests supplied with four and eight times diluted slurry, a severe inhibition of the biodegradation process was recorded in undiluted and two times diluted wastewater. Daily pH adjustment to 7 in enclosed algal-bacterial tests at several swine slurry dilutions allowed the treatment of up to two times diluted slurries (containing up to 1,180 mg N-NH(4) (+) l(-1)). The combination of high pH levels and high NH(4) (+) concentrations was thus identified as the main inhibitory factor governing the efficiency of photosynthetically oxygenated processes treating swine slurry. Measurements of soluble total organic carbon (TOC) and volatile fatty acids (VFA) present in the slurry suggested that VFA degradation (mainly acetic and propionic acid) accounted for most of the soluble TOC removal, especially during the initial stages of the biodegradation process. On the other hand, assimilation into biomass and nitrification to NO(2) (-) constituted the main NH(4) (+) removal processes in enclosed algal-bacterial systems.     

摄食对南方鲇耗氧和氨氮排泄的影响

采用流水式呼吸仪,在水温27.0±0.5℃条件下同时测定了南方鲇(Silurus meridionalisChen)摄食前后的耗氧率和排氨率。实验结果表明:摄食前标准耗氧率和标准排氨率分别为116.4±6.4mgO2/kg/h和6.9±1.4mgNH4 /kg/h。摄食后耗氧率和排氨率均呈现迅速上升,到达最大值后再缓慢下降,然后恢复到静止水平的变化趋势:最大值分别为358.8±11.4mgO2/kg/h和76.1±2.5mgNH4 /kg/h;最大值出现时间分别为10.8±1.4h和10.1±0.9h;摄食后耗氧率和排氨率发生改变的持续时间分别为36.0±2.3h和37.2±2.8h;耗氧总增量和排氨总增量分别为88.3±2.7mgO2和23.1±1.7mgNH4 。实验结果显示,鱼类排氨率在摄食后的变化过程与其耗氧率的特殊动力作用(SDA)具有类似的特征,表明二者在能量代谢机制上相互关联;南方鲇的SDA总耗能的79.4%由蛋白质分解代谢所提供。     

Seasonal variations in the physiological condition of the benthic amphipods Monoporeia affinis and Pontoporeia femorata in the Gulf of Riga (Baltic Sea)

Seasonal variations in the physiological condition of two benthic deposit-feeding amphipods were studied in two environmentally differing areas in the Gulf of Riga (Baltic Sea) with the purpose of estimating their role in benthic mineralisation. At the shallower (26 m) nearshore station, Monoporeia affinis exhibited low ammonia excretion rate (VNH ₄ ⁺ ) throughout the year. After intensive accumulation of lipids in spring, the lipid reserves of the individuals became rapidly depleted during autumn. Gravid females in winter-early spring showed exceedingly low lipid and triacylglycerol (TAG) levels compared to studies carried out in open-sea areas. Pontoporeia femorata studied at the deeper (43 m) offshore station exhibited a higher VNH ₄ ⁺ at all times with no significant seasonal variation. Lipid and TAG accumulated continuously until November, reaching higher levels than recorded previously for this species. Experiments showed that the temperature coefficient Q ₁₀ determined for VNH ₄ ⁺ is likely to depend on the recent feeding history of the amphipods. Mineralisation of nitrogen and carbon by the amphipod populations at the study sites was estimated to be 1.7-3.0 g C and 11.3-13.5 mmol NH ₄ ⁺ m^–2 yr^–1. Conclusively, both biotic and abiotic factors affect the condition of the amphipods, while the species also have genuine differences in their metabolic characteristics.     

几种控释氮肥减少氨挥发的效果及影响因素研究

采用“静态吸收法”和“土柱淋溶法”、室内模拟试验,研究几种控释氮肥施入土壤后的氨挥发损失情况、N溶出速率、土壤脲酶活性及pH值变化的关系．结果表明,施氮450mg·kg^-1土时,3种控释氮肥氨挥发损失氮总量分别比普通尿素减少49．7％、28．0％和71．2％;施氮600mg·kg^-1土时,3种控释氮肥氨挥发损失氮总量分别比普通尿素减少34．6％、12．3％和69．9％．控释氮肥能显著降低土壤氨挥发量,减少因施肥而引起的大气环境污染．控释氮肥氨挥发量与不同氮肥引起的土壤脲酶活性、pH值、土壤中氮溶出速率密切相关．土壤的氨挥发总量与肥料在土壤中溶出总量的相关系数达到0．9533,在肥料施入的前期土壤氨挥发量同土壤脲酶活性、pH值的相关系数达到0．9533和0．9908。     

Nitrogen cycling in poplar stands defoliated by insects

Large-scale outbreaks of defoliating insects are common in temperate forests. These outbreaks are thought to be responsible for substantial cycling of nitrogen (N), and its loss from the system. Gypsy moth (Lymantria dispar) populations within poplar plots were manipulated over 2 years so that the ecosystem-wide consequences of catastrophic defoliation on N cycling could be examined. The quantities of N in leaf litter-fall, ammonia volatilization and soil N pools were estimated across the two seasons. Defoliated leaf biomass was estimated from experimentally derived approximate digestibility factors and added to the mass of senesced leaf to determine total annual leaf production. Throughout the growing season the defoliation treatment peaked at about 40% in year 1 and 100% in year 2. Rapid regrowth after defoliation meant that only 45% of the annual leaf biomass was consumed in the defoliation treatment in year 2, while control plots suffered about 20% consumption each year. In each year, defoliated plots produced 20% more leaf biomass and N than the controls, a phenomenon attributed to compensatory photosynthesis. No substantial losses of N via ammonia volatilization, nitrous oxide emission or nitrate leaching were observed. Neither was there any sustained or substantial gain in the soils microbial biomass or inorganic N pools. These observations suggest that the defoliated poplars were able to compete with soil microbes and N loss mechanisms for soil N as it became available, thereby ameliorating the effects of defoliation on soil nitrogen cycling. We conclude from this study that the N mineralized from defoliation residues was conserved in this plantation ecosystem.     

Effects of hydrogen, oxygen, and ammonia low-pressure glow plasma on granular starches

Cassava, corn, high amylose corn, potato, rice Indica, rice Japonica, sweet potato, waxy corn, and wheat starches were exposed to low-pressure ammonia, hydrogen, and oxygen plasma. In every case, depolymerization of the starch polysaccharides was noted. The extent of the depolymerization depended on the nature of the starch as well as the type of plasma applied. Among three fractions of polysaccharides distinguished by their molecular weight average, the fraction of the highest molecular weight suffered the most efficient depolymerization. The relative depolymerization for the middle- and low-molecular fractions of polysaccharides was found to be starch and plasma specific. The chemical character of the plasma had very little influence on the starch polysaccharides. Only subtle oxidation effects were observed in oxygen plasma. Low-pressure glow plasma treatment appeared to be a convenient tool for a waste-less dextrinization of starch. Manipulation of the plasma variety and the time of exposure resulted in a wide spectrum of dextrins of various molecular weights and paste-forming properties.     

Hydrocelluloses with low degree of polymerisation from liquid ammonia treated cellulose

The heterogeneous hydrolytic degradation of cellulose after treatment with liquid ammonia has been studied. The level off degree of polymerisation (LODP) of liquid ammonia treated (LAT) linters is reached after 3 h when hydrolysed in hydrochloric acid (6.5 mol/l) at 60 °C. The hydrocelluloses were characterized as trimethylsilyl derivatives and as tricarbanilates. LODPs of non-activated celluloses were in the range from 55 to 77, while LAT celluloses had LODPs between 27 and 39. Trimethylsilyl derivatives and tricarbanilates gave almost identical elution curves in size exclusion chromatography indicating comparable hydrodynamic volumes. Glass transition temperatures of trimethylsilyl celluloses with DPs from 27 to 39 were found to be lower than those of the derivatives of the parent celluloses (Avicel, cotton linters) and showed a dependence on molar mass indicating that oligomeric celluloses are obtained by the method reported. Treatment of cellulose in aqueous ammonia was less efficient than liquid ammonia treatment.