Isolation, purification and identification of three peptaibols from Trichoderma koningii with antibiotic activity against Ralstonia solancearum

The use of microorganisms for biological purposes has become an effective alternative to control plant pathogens. Trichoderma koningii Smf2 was chosen from eight Trichoderma strains for its thermostatic metabolites with antibiotic activity against Ralstonia solancearum Smith. Exclusion chromatography (LH20) was used twice to partially purify targeted metabolites combined with biological test. LC/ESI-MS, a powerful tool for rapid identification and sequence determination of peptides,…     

由木糖和15N标记的甘氨酸形成的美拉德氏聚合物的氮素形态

Water-soluble,nondialyzable Maillard polymers were prepared by reacting D-xylose with ^15N-glycine (and /or glycine)at 6８℃ and pH 8.0 at equimolar concentrations of 1,0.5 and 0.1 mol L^-1,respectively, for 13 days and partitioned into acid-insoluble(MHA) and acid-soluble(MFA) fractions.The nitrogen froms in these polymers were studied by using the ^15N cross polartisation-magic angle spinning nuclear magnetic resonance(CPMAS NMR) technique in combination with chemical methods .The ^15N nuclear magnetic resonance(NMR) data showed that while the yield,especially the MHA /MFA ratio,varied considerably with the concentrations of the reactants,the nitrogen distribution patterns of these polymers were quite similar. From 65% to 70% of nitrogen in them was in the secondary amide and /or indole form with 24%-25% present as aliphatic and /or aromatic amines and 5% to 11% as pyrrole and /or pyrrole-like nitrogen,More than half (50%-77%) of the N in these polymers were nonhydrolyzable,The role of Maillard reacion in the formation of nonhydrolyzable nitrogen in soil organic matter is discussed.     

Hot water extracted organic matter: chemical composition and temporal variations in a long-term field experiment

Hot water-soluble organic matter was extracted from soil samples collected weekly between April and October in untreated and NPK+farmyard manure-fertilized plots in the 88-year-old Static Experiment (Loess Chernozem) at Bad Lauchstädt, Germany. As shown by solid-state ¹³C-nuclear magnetic resonance spectroscopy (¹³C-NMR) combined with pyrolysis-field ionization mass spectrometry this organic matter fraction was largely composed of carbohydrates and N-containing compounds, in particular amino-N species and amides. This composition and the low pyrolysis temperatures (mainly between 300 and 500°C) indicated its origin from soil biomass and root exudates and lysates, and its presence in the soil solution or weakly adsorbed by soil minerals and humic macromolecules. Long-term fertilization with NPK+farmyard manure resulted in larger mean concentrations of hot water-extracted C and N (0.933 and 0.094 g kg^-1) than soil management without fertilization (0.511 and 0.056 g kg^-1). The C and N extracted by hot water were in the range of 3–5% of total soil C and N. In the two treatments distinct temporal changes were observed, which appeared to be related to population dynamics of soil organisms, root growth and decomposition, and climatic influences on soil.     

Comparison of horse mackerel and tilapia surimi gel based on rheological and <Superscript>1</Superscript>H NMR relaxation properties

ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (¹H T ₂) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water ¹H T ₂ than tilapia in both heat and pressure treatments. The water ¹H T ₂ was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the ¹H T ₂ rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water ¹H T ₂ measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.     

Isolation and identification of degradation products of salvianolic acid A by NMR and LC-MS

Salvianolic acid A was subjected to thermal degradation condition in distilled water at 90 °C. Four degradation products, including two novel compounds (1, 2) and two known ones (5, 6), were isolated by reverse-phase semi-preparative liquid chromatography and identified on the basis of NMR and MS data. Other two degradation products (3, 4) were determined by LC-MS analysis.     

Metabolomics - A robust bioanalytical approach for the discovery of the modes-of-action of pesticides: A review

The agrochemical industry is facing great undertaking that includes increasing demand for the development of new crop protection agents that are safe for the environment and the consumers, and at the same time combat the issue of the emergence of resistance pest strains. The mode-of-action (MoA) is among the features of a bioactive compound that largely determine whether the abovementioned issues are addressed or not, and subsequently whether its commercial development will be addressed. The early discovery of the MoA of bioactive compounds could accelerate pesticide research and development by reducing the required time and costs. Based on advances in synthetic and natural product chemistry, scientists have access to a vast number of compounds that could potentially be developed as crop protection agents. The screening of such compounds with respect to their MoA requires accurate and robust bioanalytical tools. Metabolomics is a powerful bioanalytical tool that will likely play a significant role in the acceleration of the discovery of MoA of bioactive compounds. In the present review, the capabilities and principles and applications of metabolomics for the study of the MoA of herbicides, insecticides, acaricides, fungicides, and antibiotics are discussed.     

利用LF-NMR研究浸泡式真空冷却对白煮猪肉水分的影响

为了研究浸泡式真空冷却对白煮猪肉水分的影响,把浸泡式真空冷却与风冷和真空冷却比较,测定其冷却损失和水分含量,并利用低场核磁共振技术(LF-NMR)研究对水分分布的影响。试验结果表明,浸泡式真空冷却可以显著降低冷却损失,提高水分含量(p<0.05)。LF-NMR检测到了3个峰,对应的横向弛豫时间分别为T2b,T21和T22,代表肉中水的3种存在状态,即结合水、不易流动水和自由水。不同处理组3组分的弛豫时间及峰比例的变化表明:浸泡式真空冷却后的样品T21比例显著降低,T22的比例显著增加(p<0.05),表明浸泡式真空冷却可以使肉中不易流动水的比例减少,自由水比例增加。     

Post-harvest residue management effects on recalcitrant carbon pools and plant biomarkers within the soil heavy fraction in Pinus radiata plantations

Forest soils contain about 30% of terrestrial carbon (C) and so knowledge of the influence of forest management on stability of soil C pools is important for understanding the global C cycle. Here we present the changes of soil C pools in the 0-5 cm layer in two second-rotation Pinus radiata (D.Don) plantations which were subjected to three contrasting harvest residue management treatments in New Zealand. These treatments included whole-tree harvest plus forest floor removal (defined as forest floor removal hereafter), whole-tree, and stem-only harvest. Soil samples were collected 5, 10 and 15 years after tree planting at Kinleith Forest (on sandy loam soils) and 4, 12 and 20 years after tree planting at Woodhill Forest (on sandy soils). These soils were then physically divided into light (labile) and heavy (stable) pools based on density fractionation (1.70 g cm⁻³). At Woodhill, soil C mass in the heavy fraction was significantly greater in the whole-tree and stem-only harvest plots than the forest floor removal plots in all sampling years. At Kinleith, the soil C mass in the heavy fraction was also greater in the stem-only harvest plots than the forest floor removal plots at year 15. The larger stable soil C pools with increased residue return was supported by analyses of the chemical composition and plant biomarkers in the soil organic matter (SOM) heavy fractions using NMR and GC/MS. At Woodhill, alkyl C, cutin-, suberin- and lignin-derived C contents in the SOM heavy fraction were significantly greater in the whole-tree and stem-only harvest plots than in the forest floor removal plots in all sampling years. At Kinleith, alkyl C (year 15), cutin-derived C (year 5 and 15) and lignin-derived C (Year 5 and 10) contents in the SOM heavy fraction were significantly greater in stem-only harvest plots than in plots where the forest floor was removed. The analyses of plant C biomarkers and soil δ¹³C in the light and heavy fractions of SOM indicate that the increased stable soil C in the heavy fraction with increased residue return might be derived from a greater input of recalcitrant C in the residue substrate.     

黑土、栗钙土和潮土胡敏酸分子结构的差异性分析

以北方典型的黑土、栗钙土和潮土提取的胡敏酸为研究对象,通过元素分析、傅里叶红外光谱仪及13C核磁共振仪对三者进行结构分析。不同胡敏酸的各种元素含量略有差别,各种官能团含量也不同。元素分析结果来看H/C原子比潮土最高,栗钙土次之,黑土最少;O/C的原子比三者没有明显的差别;C/N比呈现由高到低的次序分别为黑土、栗钙土、潮土。3种胡敏酸的红外光谱吸收峰相似,但吸收强度有差别,如3 352 cm-1和2 931 cm-1处潮土和栗钙土信号强度相当,黑土较低,而在2 580 cm-1处三者信号差异不明显,1 720,1 620,1 420,1 220 cm-1这4个吸收峰信号强弱均为黑土最强,栗钙土次之,潮土最弱。而从核磁共振图谱可以看出潮土结构中含有更多的多糖和蛋白质类结构单元;黑土有机质含量高,芳香化程度也较高。     

集约经营雷竹林序列的土壤磷素含量与组分

在浙江省临安市三口镇、太湖源镇(西天目乡)、横畈镇等雷竹主产区采集了不同种植年限(1 a,5 a,10 a,15 a)集约经营雷竹林地以及作为对照的附近稻田(0 a)的土壤0~10、10~20、20~40 cm的样品,各年龄的土壤分别采集4个重复的剖面,对土壤磷素含量及分布作了研究,并用31P核磁共振仪分析了土壤磷素组分及比例的变化,以便为评估集约经营措施对土壤肥力和土壤环境质量的影响提供依据。结果表明:三个乡镇雷竹林土壤表层的全磷(1.96~2.01 g kg-1)、有效磷(458~468 mg kg-1)均随着雷竹种植年限的延长而呈急剧上升的趋势,但土壤有机磷增幅不大。所有土壤剖面上的全磷、有效磷和有机磷均是表层>亚表层>>底土层,呈自上而下逐渐减少的分布规律,说明土壤磷素主要富集在表层。雷竹林土壤有机磷占全磷的比例为29%~20%,有随种植年限的增加而下降的趋势。31P核磁共振分析证实无机磷酸盐组分占土壤磷素的极大部分。有机磷份量较小,其中磷酸单酯有一定比例,磷酸双酯较少,而焦磷酸酯则更少,说明在本研究的种植时间内雷竹林土壤有机磷含量变化不大。鉴于目前雷竹林地土壤有效磷已很高的现状,建议立即停用磷肥3~5年,这既不会影响雷笋的产量和品质,又可节约资源,并逐步使土壤有效磷下降、保持在一定水平上,防止潜在的污染水体的危险。