Conformational changes of humic substances induced by some hydroxy-, keto-, and sulfonic acids

We studied the effect of organic acids of plant, microbial, or anthropic origin on the molecular size distribution of dissolved humic acids (HAs). High Performance Size Exclusion Chromatography (HPSEC) was used to evaluate size changes in four different HAs upon addition of hydroxy- (glycolic and malic), keto- (glyoxylic), and sulfonic (benzenesulfonic and methanesulfonic) acids. All humic substances showed a decrease of peaks absorbance when the pH of HAs dissolved in HPSEC mobile phase was lowered from 7 to 3.5 by acid addition before analysis. This effect, combined with an increase of peaks elution volumes in most cases, was interpreted as a disruption of supramolecular humic associations into smaller-size but energy-richer conformations brought about by the formation of mixed intermolecular hydrogen bonding upon acid treatment. The extent of size variation was related to the pKa of acids and also to the chemical and stereochemical affinity of humic components with the chemical structure of the acids. Dicarboxylic malic acid was the most effective in modifying humic conformations in all HAs whereas the aromatic-rich superstructure of HA from an oxidized coal was effectively disrupted by the relatively small methanesulfonic acid and the chemically akin benzenesulfonic acid. These results suggest that the conformational association of humus dissolved in the soil solution may be systematically altered by organic acids present in the rhizosphere and might have effects on plant and microbial activities.     

Correlation studies on oil content and fatty acid profile of some Cruciferous species

Mean individual fatty acid concentration among differentspecies of the family Cruciferae are not similar because of the presence ofdifferent kind of significant relationship among the individual fatty acids.Brassica napus L., Sinapis alba L.,Raphanus caudatus L.f. Raphanus sativusL. and B. nigra (L.) Koch arecomparatively low erucic acid (<40%) containing species. Crambeabyssinica Hochst. ex. R. E. Fries collections gave as high as 60%erucic acid. Low erucic acid concentration was found associated with thepresence of high level of palmitic and oleic acid concentrations. Erucic acidconcentrations were found varied within the range of 42 to 57% among thecollections of Brassica rapa L. and B.carinata A. Braun. All the collections ofB. nigra (L.) Koch were found to havehigher proportion of linoleic acid than the corresponding oleic acidconcentration. Linolenic acid concentrations of B.nigra (L.) Koch was also higher in comparison to otherspecies of the Cruciferae. Raphanus collections were foundto contain higher levels of total saturated fatty acids as well as eicosenoicacid. Oil content of the total collections under present study did not show anysignificant relationship either with linolenic acid or with erucic acidconcentration. But significant positive relationship was observed between totaloil and erucic acid level within the collections of B.juncea Czern. & Coss. Similarly significant negativecorrelation was observed between total oil and linolenic acid content inBrassica rapa L. ssp. trilocularis (Roxb.) Hanelt, yellow sarson.     

Antifeedant activity of some pentacyclic triterpene acids and their fatty acid ester analogues

The 3-O-fatty acid ester derivatives (C(12)-C(18)) of two pentacyclic triterpenic acids, ursolic acid and oleanolic acid, were synthesized under mild esterification conditions in excellent yields (80-85%) and screened for their antifeedant activity, together with the parent acids, against the agricultural pest tobacco caterpillar larvae (Spodoptera litura F) in a no-choice laboratory study. The Urs-12-ene-28-carboxy-3beta-octadecanoate and olean-12-ene-28-carboxy-3beta-hexadecanoate were found to exhibit exceptionally potent antifeedant activities at 50 microg/cm(2) concentration, even after 48 h.     

Decomposition of lipids in soils: Free and esterified fatty acids,alcohols and ketones

Because lipids are important to the properties of soils and the composition of sedimentary organic matter, the rates of decomposition of selected lipids in soils were determined. The rates of decomposition of total lipid extracts from plant materials and of carbohydrates showed marked differences that were dependent on the biological activity of the soils. In biologically-active soils, such as a rendzina or a brunic luvisol, pure lipids were readily degraded, regardless of their functional groups and chain length. An exception was montanic acid (nC-28), which was refractory in all soils studied. In acid soils, such as a glossic luvisol or a dystric histosol, both chain length and functional groups affected the rate of decomposition of lipids, e.g. after 4 weeks at 28 C, the ratio of decomposition of oleic acid to, stearic acid was as high as 5. The same effect was found when 3-octadecanone (C-18 ketone) was compared to myristone (C-27 ketone). In most soils, the rate of decomposition of free and esterified stearic acid was similar, implying preliminary enzymatic hydrolysis of both the waxes and the fats.     

Lipase-catalyzed synthesis of fatty acid diethanolamides.

Diethanolamides are nonionic emulsifiers widely used in industries such as cosmetics and as corrosion inhibitors. Candida antarctica lipase (Novozym 435) was used to catalyze the amidation of various fatty acids with diethanolamine. Contents of fatty acids, metal ions, and water affected the yields of diethanolamides. Hexanoic acid was the best substrate among all acyl donors. Yields of hexanoyl diethanolamide (HADEA), lauroyl diethanolamide (LADEA), and oleoyl diethanolamide (OADEA), obtained after 24 h of lipase-catalyzed reaction at 50 degrees C and 250 rpm with 90 mM fatty acid and 360 mM diethanolamine in acetonitrile, were 76.5, 49.5, and 12.1%, respectively. Addition of 1 mM metal salts increased the yields of HADEA and LADEA. Kinetic analysis showed that the yields of HADEA and LADEA in lipase-catalyzed reactions were largely associated with the rate of the forward reaction constant k(1). Anhydrous enzyme was found to be the best for the amidation reaction. Study on the enzyme operational stability showed that C. antarctica lipase retained 95 and 85% of the initial activity for the syntheses of HADEA and LADEA, respectively (even after repeated use for 10 days). The reaction runs smoothly without the use of hazardous reactants, and the developed method is useful for the industrial application.     

Physical properties of shark gelatin compared with pig gelatin

Physical properties of shark gelatin were examined during gel formation and postgelation in comparison with pig gelatin. Samples with various concentrations and pH values were evaluated by breaking strength, dynamic viscoelasticity, and dynamic light scattering. Sol-gel and gel-sol transition temperatures for shark gelatin were remarkably lower than those for pig gelatin. Shark gelatin gel shows a narrower pH range to form a stable gel compared with pig gelatin. Melting enthalpy of shark gelatin gel was greater than that of pig gelatin gel, and G' of shark gelatin gel changed more extensively with rising temperature in comparison with pig gelatin gel. It is concluded that shark gelatin has different characteristics from pig gelatin not only for gel characteristics but also for the solution property.     

植物单宁酸交联明胶的条件优化及性质分析

该文用单宁酸作交联剂对明胶进行交联改性,通过响应面法优化反应条件并建立回归模型,并对交联前后的明胶进行十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、紫外光谱和黏度等3方面的分析测定,确认单宁酸交联对明胶所产生的交联作用,开发新食品配料交联明胶。结果显示:适宜的交联反应条件为反应温度47.5℃,时间50h,单宁酸添加量80mg/g明胶。性质分析表明,与原料明胶相比交联明胶一些性质发生变化,紫外光谱分析发现交联明胶在276nm出现新吸收峰,表明交联明胶分子中存在苯环;电泳后交联明胶的蛋白质条带色泽明显变浅,且交联度越大条带色泽越浅,此外,交联明胶溶液的黏度明显增大,说明单宁酸交联处理使交联明胶中有更多的大分子物质生成。     

Comparative studies of some phenolic compounds (quercetin, rutin, and ferulic acid) affecting hepatic fatty acid synthesis in mice

The physiological activities of some phenolic compounds affecting hepatic fatty acid synthesis in mice were compared. Male ICR mice were fed an experimental diet containing 1% quercetin dihydrate, rutin, or ferulic acid or a control diet free of phenolic compounds for 15 days. Quercetin significantly lowered serum cholesterol and phospholipid levels in mice. Also, the serum triacylglycerol level was considerably lower in mice fed the quercetin-containing diet than in those fed a diet free of phenolic compounds, although the difference was not significant. Rutin and ferulic acid did not affect these parameters. Quercetin significantly reduced the activity and mRNA levels of various enzymes involved in hepatic fatty acid synthesis. Rutin reduced a few of the parameters for lipogenesis, but ferulic acid did not affect any of the parameters. It was suggested that a reduction in hepatic lipogenesis is the mechanism underlying the hypolipidemic effect of quercetin.     

红外辐射制备柠檬酸糯米淀粉酯工艺优化及功能特性

为提高柠檬酸淀粉酯制备效率,拓展淀粉在工业领域的应用价值,以糯米淀粉为研究对象、柠檬酸为酯化剂,红外辐射为核心制备技术,取代度为衡量指标,用单因素和响应面法优化柠檬酸淀粉酯的制备工艺条件,并对改性前后淀粉的理化性质、微观结构测定分析.最佳工艺参数为:红外辐射照度2474 W/m2、红外辐射时间7.1 min、pH值为2...     

一株耐盐溶磷真菌的筛选、鉴定及其生物肥料的应用效果

【目的】从内蒙古种植向日葵的盐碱地中筛选高效溶磷真菌,为农业生产中增产节肥,开发耐盐、溶磷微生物肥料提供菌种资源。【方法】利用形态特征和ITS rDNA序列鉴定菌株;LC-MS技术测定菌株M2在液体培养基中分泌有机酸和植物激素含量,明确菌株M2的溶磷和促生机理。采用液体摇床培养试验测定了鉴定菌株的溶磷能力。试验处理包括:在磷酸三钙、磷酸铝和5个磷矿的磷矿粉制备的100 mL难溶磷磷源 (含5 g/L难溶磷) 中,接入1 mL灭菌培养液对照,和分别接种1 mL斜卧青霉菌P83和草酸青霉菌M2共15个处理。置于28℃、160 r/min摇床培养,分别于3、6和9 d,取菌液5 mL,在12000 r/min、4℃离心5 min,取上清液测定有效磷含量。采用含NaCl的固体培养基测定菌株的耐盐性。NaCl含量分别为0%、5%、7.5%、10%和12.5%的PDA平板中接入溶磷菌,置于28℃恒温培养箱中5 d,观察并记录菌丝的生长状况。采用盆栽试验方法检验了菌株的溶磷能力。以玉米种子 (郑单958) 为供试作物,以水稻土、黏性潮土、盐潮土和石灰性潮土为供试土壤,以Ca₃(PO₄)₂、AlPO₄ 和昆阳磷矿粉 (RP) 为供试磷源 (磷源用量为1.0 g/kg土壤)。设置只加入灭菌草炭和Pikovskaya培养液对照,分别接种溶磷菌P83、M2,共计38个处理,144盆。玉米播种40天后收获,测定植株鲜重、干重和玉米根际土壤有效磷含量。田间试验以花生为供试作物,设置只加灭菌草炭和Pikovskaya培养液对照和分别接种ATCC20851、P83、M2溶磷菌剂三个处理。花生生长155 d后收获,称量花生植株鲜重和干重、花生果实鲜重和干重,同时采集花生根部土壤测定有效磷含量。【结果】溶磷菌株M2鉴定为草酸青霉 (Penicillium oxalicum)。液体培养基摇床培养6 d后,接种菌株M2,以Ca₃(PO₄)₂为磷源的上清液中有效磷含量达972 mg/L,Ca₃(PO₄)₂溶解率为59.2%;以AlPO₄为磷源的有效磷含量达988 mg/L,溶解率为48.2%;以江苏锦屏、贵州开阳、云南晋宁、河北钒山和云南昆阳磷矿粉为磷源的有效磷释放量达21.0～556 mg/L。菌株M2在7.5%NaCl培养基中正常生长。盆栽试验结果发现,菌株M2对玉米植株促生效果显著,玉米植株鲜重比不接种菌剂 (CK) 提高26.4%～99.2%、干重增加20.0%～262.9%,土壤有效磷提高19.2～25.3 mg/kg。菌株M2与4种土壤的适配性均高于对照菌株P83。田间小区花生产量结果显示,接种溶磷菌剂M2增产效果最好,花生果实产量达4.50 t/hm2,比CK增加0.85 t/hm2,增产23.29%。菌株M2 在含有磷酸三钙、磷酸铝和开阳磷矿粉3种难溶磷培养液中经过6 d培养,均产生7种有机酸,其中草酸和柠檬酸含量最高,分别为653.46 mg/L和269.61 mg/L;培养液中均能检测到吲哚乙酸 (IAA) 和玉米素,IAA含量为32.38～66.17 mg/L,玉米素浓度为0.05～0.07 mg/L。【结论】获得了一株耐盐、高效溶解多种难溶磷的草酸青霉菌M2,可显著增加土壤有效磷,促进玉米生长和花生增产,与4种典型土壤适配性好,具有良好的农业应用前景。     

Genotypic variation in fatty acid content of blackcurrant seeds.

The fatty acid composition and total fatty acid content of seeds from 36 blackcurrant genotypes developed at the Scottish Crop Research Institute were examined. A rapid small-scale procedure, involving homogenization of seeds in toluene followed by sodium methoxide transesterification and gas chromatography, was used. There was considerable variation between genotypes. The gamma-linolenic acid content generally varied from 11 to 19% of the total fatty acids, but three genotypes had higher values of 22-24%, levels previously not reported for blackcurrant seed and similar to those for borage seed. Other nutritionally important fatty acids, stearidonic acid and alpha-linolenic acid, varied from 2 to 4% and 10-19%, respectively. The mean total fatty acid contents ranged from 14 to 23% of the seed, but repeatability was poor. The results are discussed. Blackcurrant seeds are mainly byproducts from juice production, and the study shows the potential for developing blackcurrant genotypes with optimal added value.     

Potassium release characteristics and mineralogical characteristics of some delaware soils

Abstract

Twenty‐eight agriculturally important Delaware soils were cropped intensively in a greenhouse experiment. There was no consistent positive correlation between K uptake and percent sand, silt, clay, clay minerals of the clay fraction, K‐feld‐spars of the sand fraction or K‐feldspar weathering of the soils from the A horizon. Only potassium feldspar from the sand fraction and K‐feldspar weathering correlated with K uptake in the soils of the B horizon. This correlation was only significant at the latter part of the experiment when nonexchangeable K was probably the source of plant available K.     

Seasonal changes and the effects of fertiliser on some chemical,biochemical and microbiological characteristics of high-producing pastoral soil

Summary A 2-year study (1983–1984 to 1984–1985) was conducted to estimate temporal and seasonal changes and the effects of fertiliser on some soil chemical, biochemical and microbiological characteristics. The soil used was a Typic Vitrandept under grazed pasture. Soil samples were taken regularly to a depth of 75 mm from paired unfertilised and fertilised (500 kg ha^– 30% potassic superphosphate) plots. Except for organic C, fertiliser had little or no effect on the characteristics measured. Organic C averaged about 9.2% in unfertilised soil and was about 0.3% higher in the fertilised soil. The size of the microbial biomass fluctuated widely in the 1st year (3000 g C g^–1 in February to 1300 g C g^–1 in September) but there was less variation in the 2nd year (range 1900 g C g^–1 to 2500 g C g^–1 soil). CO₂ production values (10- to 20-day estimates averaged 600 g of CO₂-C g^–1 soil) were generally higher in spring compared to the rest of the year. Water extractable C increased over winter and declined through spring in both years (range 50 g C g^–1 soil to 150 g C g^–1 soil). Mineral-N flush values were higher in summer (300 g N g^–1 soil) and lower in winter months (200 g N g^–1 soil). The pattern of variation of microbial N values was one of gradual accumulation followed by rapid decline. This rapid decline in values occurred in spring and autumn (range 130–220 g N g^–1 soil). N mineralisation and bicarbonate-extractable N showed no clear trend; these values ranged from 100–200 and 122–190 g N g^–1 soil, respectively. There was a significant correlation (0.1%) between N mineralisation and bicarbonate-extractable N in the late summer-autumn-early winter period (February–August) in both years but not in spring. These results and their relationships to climatic factors and rates of pasture production are discussed.     

Inhibition of bacteriophage m13 replication with esterified milk proteins

Esterified milk proteins [methylated (Met) or ethylated (Et) alpha-lactalbumin (ALA), beta-lactoglobulin (BLG), and beta-casein (BCN)], unmodified native milk proteins, and native basic proteins (calf thymus histone and hen egg white lysozyme) were tested for their antiviral activity against the bacteriophage M13 and for their influence on its replication (except BCN). All esterified milk proteins showed an antiviral activity against the bacteriophage M13, proportional to the extent of esterification and, hence, to the increased basicity of the modified proteins. Antiviral activity of 100% Met-BLG disappeared after its pepsinolysis but not after its trypsinolysis. The antiviral activity of Met-BLG was much higher than that of native basic proteins (histone and lysozyme). One hundred percent Met-BLG and 73% Et-BLG inhibited the replication of bacteriophage M13 completely, whereas 60% Met-ALA inhibited phage replication partially. Calf thymus histone inhibited the replication of bacteriophage M13 at a lower extent (20%) than Met- and Et-BLG (100% inhibition). Protein concentration, pH, and concentration of the Escherichia coli culture in the preincubation medium of the virus were other factors influencing antiviral activity. Interactions of esterified proteins with the phage DNA (phenol extracted) followed the same pattern as observed during studies of the inhibition of the phage replication: Met-BLG > Et-BLG > or = Met-ALA.     

Encapsulation of lycopene extract from tomato pulp waste with gelatin and poly(gamma-glutamic acid) as carrier

Tomato pulp waste, a byproduct obtained during the processing of tomato juice, has been shown to be a rich source of lycopene. The objectives of this study were to use gelatin and poly(gamma-glutamic acid) (gamma-PGA) as coating materials for the encapsulation of lycopene extract from tomato pulp waste. Initially, lycopene was extracted with supercritical carbon dioxide, followed by microencapsulation using an emulsion system consisting of 4.5% gelatin, 10% gamma-PGA, and 4.8% lycopene extract. Analysis of differential scanning calorimetry revealed that the thermal stability of the coating material could be up to 120 degrees C, with a mean particle size of 38.7 microm based on Coulter counter analysis. The total weight of microencapsulated powder was 617 microg with the yield of lycopene being 76.5%, indicating a 23.5% loss during freeze drying. During storage of microencapsulated powder, the concentrations of cis-, trans-, and total lycopene decreased along with increasing time and temperature. A fast release of lycopene in the powder occurred at pH 5.5 and 7.0, while no lycopene was released at pH 2.0 and 3.5.     

Characterization of sphingolipids from sunflower seeds with altered fatty acid composition

Sphingolipids are a group of lipids that are derived from long-chain 1,3-dihydroxy-2-amino bases and that are involved in important processes in plants. Long-chain bases are usually found bound to long-chain fatty acids forming ceramides, the lipophilic moiety of the most common sphingolipid classes found in plant tissues: glucosyl-ceramides and glucosyl inositol phosphoryl-ceramides (GIPCs). The developing sunflower seed kernel is a tissue rich in sphingolipids, although, importantly, its glycerolipid composition can vary if some steps of the fatty acid synthesis are altered. Here, the sphingolipid composition of the seed from different sunflower mutants with altered fatty acid compositions was studied. The long-chain base composition and content were analyzed, and it was found to be similar in all of the mutants studied. The sphingolipid species were also determined by mass spectrometry, and some differences were found in highly saturated sunflower mutants, which contained higher levels of GIPC, ceramides, and hydroxyl-ceramides.     

Effects of different chemical modifications on peat humic acid and their bearing on some agrobiological characteristics of soils

Abstract

Twelve preparations from peat humic acid were obtained through laboratory treatments modifying its structural parameters, oxygen (O)‐containing functional groups and nitrogen (N) content. The treatments included acetylation, amidation, ammonia fixation, methylation, nitration, oximation, sulphonation, and selective degradations. The transformed humic products were characterized by routine laboratory analyses. Then, plant yield and different properties of two soils treated with the corresponding potassium (K)‐humates were determined in greenhouse experiments. The main effects and interactions between parameters affecting the response of soil and plant to humic acid application were analyzed through factorial designs. Whereas the application rate (2 to 4 Mg/ha) had no great bearing on plant yield (accounting for between 84 to 176% of the untreated soils), the opposite occurred with aggregate stability and cation exchange capacity. Among the parameters examined in the humic acids, the hydrogen/carbon (H/C) atomic ratio showed the most significant correlation with plant yield (inverse correlations with the optical density and relative fluorescence intensity were found), whereas the amounts of O or N were in general unrelated to the agrobiological properties of the amended soils. It is postulated that the differences observed in the edaphic role of the humic preparations were not due to a great straightforward influence of the chemical transformations applied, but mainly reflected their indirect effects on the polymer arrangement of the humic acid through changes in the surface properties of the whole macromolecular system.