爵床提取物的抑菌杀虫活性研究

爵床(Justicia procumbens var.procumbens L.)是一种传统中药。为探明爵床提取物的抑菌杀虫活性,采用冷浸和超声波提取相结合的方法,分别获得了爵床甲醇、氯仿、丙酮、乙酸乙酯和正己烷等溶剂提取物;并应用抑菌圈法研究了5种提取物对柑橘炭疽病菌(Colletotrichum gloeosprioides)、芦笋茎枯病菌(Phomopsisasparagi)、稻瘟病菌(Pyricularia grisea)、棉花红腐病菌(Fusarium graminearum)和草莓灰霉病菌(Botrytiscinerea)等5种植物病原真菌的抑制效果,测定了甲醇提取物对柑橘炭疽病、芦笋茎枯病、草莓灰霉病和柑橘溃疡病(Xanthomonas campestris)等4种植物病菌及白蚊伊蚊(Aedes albopictus)、家蝇(Musca domestica)和菜青虫(Pieris rapae)等3种害虫的毒力。结果表明,不同极性溶剂提取物8 mg.mL 1对5种植物病原真菌均有一定的抑制作用,其中甲醇提取物对柑橘炭疽病菌、芦笋茎枯病菌、草莓灰霉病菌的抑制率均达50%以上。爵床甲醇提取物具有较强的抑菌杀虫活性,对柑橘炭疽病菌、芦笋茎枯病菌和草莓灰霉病菌菌丝生长的抑制中浓度(EC50)分别为5.94 mg.mL 1、4.61 mg.mL 1和5.27 mg.mL 1,EC90分别为63.69 mg.mL 1、58.01 mg.mL 1和54.57 mg.mL 1;0.25~1.00 mg.mL 1爵床甲醇提取物对柑橘溃疡病病菌显示强抑菌作用,0.125 mg.mL 1显示中度抑菌作用,最小抑制浓度(MIC)为0.062 5 mg.mL 1;爵床甲醇提取物对白蚊伊蚊、家蝇和菜青虫的致死中浓度(LC50)分别为0.195 8 mg.mL 1、0.351 4 mg.mL 1和0.287 7 mg.mL 1,LC95分别为0.988 4 mg.mL 1、3.053 2mg.mL 1和2.584 4 mg.mL 1。因此,爵床提取物作为生物农药,在农业生产中具有较好的应用前景。     

Combined effects of the antibiotic sulfadiazine and liquid manure on the soil microbial‐community structure and functions

Sulfonamides are the second most used antibiotic class in veterinary medicine and applied to livestock to treat bacterial infections. Subsequently, they are spread onto agricultural soils together with the contaminated manure used as fertilizer. Both manure and antibiotics affect the soil microbial community. However, the influence of different liquid manure loads on effects of antibiotics to soil microorganisms is not well understood. Therefore, we performed a microcosm experiment for up to 32 d to clarify whether the function and structure of the soil microbial community is differently affected by interactions of manure and the antibiotic sulfadiazine (SDZ). To this end selected concentrations of pig liquid manure (0, 20, 40, 80 g kg^–1) and SDZ (0, 10, 100 mg kg^–1) were combined. We hypothesized that incremental manure amendment might reduce the effect of SDZ in soils, due to an increasing sorption capacity of SDZ to organic compounds. Clear dose‐dependent effects of SDZ on microbial biomass and PLFA pattern were determined, and SDZ effects interacted with the liquid manure application rate. Soil microbial biomass increased with incremental liquid manure addition, whereas this effect was absent in the presence of additional SDZ. However, activities of enzymes such as urease and protease were only slightly affected and basal respiration was not affected by SDZ application, while differences mostly depended on the concentration of liquid manure. These results illustrated that the microbial biomass and structural composition react more sensitive to SDZ contamination than functional processes. Furthermore, effects disproportionally increased with incremental liquid manure addition, although extractable amounts of SDZ declined with increasing liquid manure application.     

香蕉枯萎病拮抗菌株BS11抗真菌活性物质的研究

[目的]对枯草芽孢杆菌BS11抗真菌活性物质进行研究,为该菌株的进一步开发应用提供参考。[方法]比较了枯草芽孢杆菌BS11在LB和NB培养基上的生长情况,比较了3种方法提取该菌株活性物质的效果,并探讨了该菌株的最佳培养条件。[结果]以香蕉枯萎病菌为指示菌,发现拮抗菌在LB和NA 2种不同培养基中有很明显的差别,LB培养基中生长繁殖速度快,但上清液活性很低,NA培养基中繁殖速度较慢,上清液活性却较好;乙醇沉淀法和乙酸乙酯萃取法均不能提取到活性物质,硫酸铵沉淀法基本上可将活性物质提取出来;BS11最佳的培养条件为初始p H7,温度30℃,通气量60 ml;发酵上清液有蛋白酶、纤维素酶活性,但没有几丁质酶活性。[结论]枯草芽孢杆菌BS11株所产的抗真菌活性物质具有性质稳定、广谱、易于提取等优点,为其应用于植物病害防治提供了理论依据。     

Effects of soil properties and trace metals on urease activities of calcareous soils

A study was conducted to investigate the relationship between urease activity and some physical, chemical, and microbiological properties of soils from central Iran. Inhibitory effects of Cr, Cd, and Pb on urease activity were also studied. Results indicated that no significant difference was observed between urease activity of field-moist and air-dried soils. Soil organic C and total N correlated highly significantly with urease activity, with r values of 0.899*** and 0.797***, respectively. There was also a significant correlation between urease activity and the number of bacteria grown on urea-agar media, with r value of 0.470*. A significant negative correlation (r =–0.492*) was observed between urease activity and electrical conductivity of saturation paste extracts. There were no significant correlations between urease activity and soil textural properties, pH, calcium carbonate equivalent, cation exchange capacity, and populations of soil bacteria on nutrient agar and population of soil fungi on potato dextrose agar. Both Cd and Pb inhibited urease activity to a similar extent and to a greater extent than did Cr.     

Organic matter status and the size,activity and metabolic diversity of the soil microflora as indicators of the success of rehabilitation of mined sand dunes

The effectiveness of the rehabilitation of mined sand dunes on the northern coast of KwaZulu–Natal, South Africa, was assessed based on measurements of the total and labile organic matter content and the size, activity and metabolic diversity of the soil microflora. Soil was sampled (0–10 cm) after 0, 5, 10, 20 and 25 years of rehabilitation and compared with soil under undisturbed native forest and under long-term commercial pine forest. Following topsoil removal, stockpiling and respreading on reformed dunes, there was a massive loss of organic C such that, at time zero, organic C content was only 24% of that present under native forest. Soil organic C content increased progressively during rehabilitation until, after 25 years, it represented 93% of that present under native forest. The pattern of change in light-fraction C, KMnO₄-extractable C, water-soluble C, microbial biomass C, basal respiration and arginine ammonification rate was broadly similar to that for organic C, but the extent of the initial loss and the magnitude of the subsequent increase differed. Microbial biomass C, water-soluble C and KMnO₄-extractable C, expressed as a percentage of organic C, declined during rehabilitation as humic substances progressively accumulated. Principal component (PC) analysis of catabolic response profiles to 36 substrates revealed that the catabolic diversity of microbial communities differed greatly between native forest, commercial pine forest, 0 years and 10 years of rehabilitation. On the PC1 axis, values for soils under native forest and after 25 years rehabilitation were similar, but there was still separation on the PC2 axis. The main factor explaining variation in response profiles on the PC1 axis was organic C content; and the greatest catabolic diversity occurred in soils under native forest and after 25 years of rehabilitation.     

蒋家沟泥石流堆积扇区变迁及整治

蒋家沟是世界闻名的高频大型泥石流沟。200多年来的泥石流活动及人为减灾影响,造成其堆积扇及其相邻的沟域和小江河床的巨变。沟内7.48亿m³松散物质及年235万t的补给量必将在今后长期控制影响小江河床,危害400多hm²农田及公路。通过泥石流及人为活动影响历史分析研究,掌握河流及堆积地貌发展变化趋势,为其近期整治提供合理措施方案及长期人为积极活动影响提供方向。     

水、氮供应和土壤空间所引起的根系生理特性变化

在限制根系生长的胁迫条件下.,研究了补充和不补充供应水、氮对玉米根系生理特性及养分吸收的影响。结果表明.,正常生长条件下.,水、氮供应促进了根系生长.,增加了根系吸收总面积、活跃吸收面积和TTC还原量.,促进了根系对养分的吸收.,从而提高了产量.;限制根系生长.,水分的作用与正常条件下相同.,氮素的作用则受控于土壤水分。补充灌水增强了氮肥作用.,供氮促进了根系生长.,改善了根系生理特性.,减少了限制根系生长所引起的不良影响.;不补充灌水限制了氮肥作用的发挥.,供氮导致了根系生物量和生理特性下降.,加重了限制根系生长的不良影响。     

新微生物农药抑霉菌素的研究

抑霉菌素产生菌经形态学特征及生理生化特性等分类学研究 ,定名为刺孢吸水链霉菌天目山亚种。主要活性组分经UV、HNMR、DEPTCNMR及H HCOSY等光谱分析 ,推知其化学结构系一新的核苷类抗生素。采用二倍稀释法对其展开体外抗菌活性研究 ,结果表明抑霉菌素对单丝壳菌、担子菌、圆形刺盘孢等多种农作物真菌病害病原菌具有强生长抑制作用     

Effect of molecular complexity and acidity of earthworm faeces humic fractions on glutamate dehydrogenase,glutamine synthetase,and phosphoenolpyruvate carboxylase in Daucus carota α II cells

Carrot cells were grown in cultures supplemented with two hormones [2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (6BAP)] and two humic fractions extracted from earthworm faeces, one with high acidity and a low apparent molecular size (<3500) and the other with low acidity and a large molecular size. 2,4-D stimulated growth through an effect on cell enlargement, while the strongly acidic humic fraction (0.2 mg l^-1) and the weakly acidic fraction (1 mg l^-1) were both less effective. With 4–16 h of pre-incubation, the highly acid humic fraction, mainly alone, induced the best increase in protein content; the effect of the weakly acid humic fraction and the hormones was generally less important. The two humic fractions also differed in their influence on glutamate dehydrogenase activity. After 2 h of pretreatment, the highly acidic fraction increased glutamate dehydrogenase activity, while the other fraction did not affect it. After 4–16 h of pre-incubation, the activity of this enzyme was still not influenced by these humic fractions. The presence of the two hormones did not interfere with the humic matter effects. Glutamine synthetase activity was not affected by a pre-incubation of up to 4 h with the two humic fractions, but it was stimulated after 8–16 h of pre-incubation. A 2,4-D+6BAP mixture stimulated glutamine synthetase activity (from +12 to +50%). Again, the presence of the hormones did not interfere with the effects induced by the humic fractions. After 16 h of pre-incubation, phosphoenolpyruvate carboxylase activity was increased by the highly acidic humic fraction (+93%) and by both humic fractions together (+34%). An explanation of the different incubation times necessary for the humic fractions to exert stimulatory effects on these enzymes is proposed here. The regulatory properties of the strongly acidic humic fraction appeared to depend on the combination of high acidity (expecially carboxylic C) with low molecular size.     

Arylsulfatase activity in soil and soil extracts using natural and artificial substrates

The arylsulfatase activity of soil and humic arylsulfatase complexes extracted from soil were measured using the substrates p-nitrophenyl sulfate and low molecular weight (500–10000) soil ester sulfate compounds. Soil samples from the Aphorizon of a Podzol from S-amended wheat plots and a Regosol from dykeland hayfield plots were investigated. Soil arylsulfatase activity (assayed with p-nitrophenyl sulfate) in the fall was significantly higher than spring samples; however, no seasonal differences were observed when humic-arylsulfatase complexes were assayed with p-nitrophenyl sulfate. The discrepancy between arylsulfatase activity in soil and soil extracts was probably due to inhibitors which were found in soil materials. These results appear to support the theory that abiotic arylsulfatase is a relatively stable and persistent component of soil. There was a marked difference in the response by humic-arylsulfatase complexes to the artificial substrate p-nitrophenyl sulfate and natural low molecular weight soil substrates. Humic-arylsulfatase complexes hydrolysed 35–80% of added low molecular weight substrates depending on the treatment. The molecular size, concentration, and chemical composition of the low molecular weight ester sulfate compounds affected hydrolysis of the low molecular weight substrates. The response by humic-arylsulfatase complexes to the chromogenic ester sulfate, p-nitrophenyl sulfate did not reflect the ability of these complexes to hydrolyse natural soil substrates. In an experiments we examined arylsulfatase activity and soil S status in relation to the total S in plant tissue and grain from wheat plants grown in the Podzol. Tissue S was more strongly associated with soil S than the wheat grain. Hydriodic acid-S, Ca(H₂PO₄)₂-extractable sulfate, and hydrolysable ester sulfates in the high molecular weight (>10000) and low molecular weight (500–10000) fractions of soil organic matter extracts were strongly positively correlated with tissue S. Arylsulfatase activity in soil and humic-arylsulfatase extracts assayed with p-nitrophenyl sulfate were also strongly correlated with tissue S, while humic-arylsulfatase activity assayed with the low molecular weight substrate was negatively correlated with tissue S.