不同抗性烤烟根系分泌单糖特征及其对黑胫病菌的化感效应

为探讨烤烟根系分泌单糖的品种差异及与黑胫病的相关性,该研究以‘NC102’、‘K326’、‘云87’和‘红花大金元’4个烤烟品种为试验材料,测定了各烤烟品种根系、根际土中的单糖及对黑胫病的化感作用。结果表明:(1)在各烤烟品种的根系和根际土中均检出了木糖、阿拉伯糖、葡萄糖和半乳糖,检出的糖组分中以葡萄糖含量最高。(2)在烤烟团棵期时,根际土中的葡萄糖含量在高抗品种‘NC102’和中抗品种‘K326’中分别为2.255和4.744μg·g~(-1),中感品种‘云87’和高感品种‘红花大金元’分别为7.100和11.068μg·g~(-1);各烤烟品种团棵期时根际土中的单糖总量表现为:‘NC102’(5.346μg·g~(-1))‘K326’(7.844μg·g~(-1))‘云87’(10.551μg·g~(-1))‘红花大金元’(15.579μg·g~(-1))。(3)根际土中葡萄糖含量、单糖总量均表现为感病品种高、抗病品种少的趋势;感病品种根际土中单糖总量在团棵期时高,而在其他时期时较低。(4)各单糖和混合糖溶液对黑胫病菌的生长均表现为促进作用,单一糖在2.000mg·mL~(-1)处理下促进作用最强,混合糖在4.000mg·mL-1处理下促进作用最强。研究发现,烤烟感病品种在生长发育前期通过根系分泌较多的单糖到根际土中,为土壤中黑胫病菌的生长发育提供了物质和能源,促进了烟草黑胫病菌的生长,导致烟草黑胫病的发生。     

落叶松根际土壤磷的有效性研究

野外用剥落法采集落叶松(Larixgmelini)根际土与非根际土,分析P浓度的变化,结果表明,落叶松根际土与非根际土全P浓度无明显差异,但根际土有效P却明显高于非根际土.12年生时根际土有效P增加12.6%,40年生时增加23.4%,表明落叶松根际对土壤中的P具有活化作用.落叶松根际土无机P各组分与非根际土亦有差异,表现出根际土OP低于非根际土,AlP、FeP、CaP和NH4ClP则高于非根际土的趋势.落叶松根际土的pH低于非根际土,但落叶松根际并未发生明显酸化.落叶松根际有效P与pH变化相关不显著.     

落叶松根限土壤磷的有效性研究

野外用剥落法采集落叶松（Larix gmelini）根际土与非根际土,分析P浓度的变化,结果表明,落叶松根际土与非根际土全P浓度无明显差异,但根际土有效P却明显高于非根际土,12年生时根限土有效P增加12.6％,40年生时增加23.4%,表明落叶松根限对土壤中的P具有活化作用,落叶松根限土无机P各组分与非根际土亦有差异,表现出根际土O－P低于非要际土,Al-P,Fe-P,Ca-P和NH4Cl-P则高于非根际土的趋势,落叶松根限土的pH低于非根际土,但落叶松根限并未发生明显酸化,落叶松要际有效P与pH变化相关不显著。     

喀斯特不同植被恢复阶段土壤有机酸季节变化与有效氮磷的关系

植物分泌有机酸在提高土壤养分有效性方面起到重要作用。为了解喀斯特地区不同植被恢复阶段土壤有机酸含量季节性变化与氮磷有效性的关系,在灌木林和原生林各选择3种优势植物,测定雨季和旱季两个季节根际土和非根际土的有机酸含量、碳氮磷含量和比值、有效性氮磷含量及微生物生物量碳。结果表明:原生林植物根际土的草酸含量高于灌木林,而苹果酸和乙酸含量则低于灌木林;根际土草酸含量均高于非根际土;2个植被根际土和非根际土的草酸含量在雨季高于旱季,而苹果酸和乙酸含量则低于旱季;土壤草酸含量与有机碳、全氮、全磷和N∶P值呈显著正相关,与C∶N呈显著负相关;土壤有效氮和有效磷与草酸和微生物生物量碳呈显著正相关。上述结果表明,植物分泌有机酸的季节性变化与土壤养分状态和自身养分需求相关,而有机酸耦合微生物对养分有效性的提高具有积极的作用。因此,根际土的有机酸季节变化可能是喀斯特生态系统中植物适应土壤养分限制的一种重要机制。     

喀斯特不同植被恢复阶段土壤有机酸季节变化与有效氮磷的关系

植物分泌有机酸在提高土壤养分有效性方面起到重要作用。为了解喀斯特地区不同植被恢复阶段土壤有机酸含量季节性变化与氮磷有效性的关系,在灌木林和原生林各选择3种优势植物,测定雨季和旱季两个季节根际土和非根际土的有机酸含量、碳氮磷含量和比值、有效性氮磷含量及微生物生物量碳。结果表明:原生林植物根际土的草酸含量高于灌木林,而苹果酸和乙酸含量则低于灌木林;根际土草酸含量均高于非根际土; 2个植被根际土和非根际土的草酸含量在雨季高于旱季,而苹果酸和乙酸含量则低于旱季;土壤草酸含量与有机碳、全氮、全磷和N∶P值呈显著正相关,与C∶N呈显著负相关;土壤有效氮和有效磷与草酸和微生物生物量碳呈显著正相关。上述结果表明,植物分泌有机酸的季节性变化与土壤养分状态和自身养分需求相关,而有机酸耦合微生物对养分有效性的提高具有积极的作用。因此,根际土的有机酸季节变化可能是喀斯特生态系统中植物适应土壤养分限制的一种重要机制。     

不同林龄云杉人工林的根系分泌物与土壤微生物

采用野外原位收集方法,对川西米亚罗林区不同林龄(9、13、31年)的粗枝云杉人工林根系分泌物和土壤微生物进行了研究.结果表明:不同林龄粗枝云杉人工林根系的单位质量、长度、面积及根尖分泌速率存在显著差异,表现为9年生云杉林的分泌速率显著大于13年生和31年生云杉林.13年生云杉林的根系活力显著小于9年生和31年生云杉林.不同林龄粗枝云杉人工林的根际土、非根际土微生物量碳(MBC)和氮(MBN)存在显著差异,根际土表现为31年生13年生9年生,非根际土为13年生31年生9年生.随林龄的增加,粗枝云杉的根际土细菌、真菌、放线菌磷脂脂肪酸含量及总量呈现出高-低-高的变化趋势,而非根际土细菌、真菌磷脂脂肪酸含量、总量及真菌/细菌呈低-高-低的趋势.粗枝云杉根系对土壤MBC、MBN及功能群磷脂脂肪酸含量具有正根际效应.     

毛竹根际与非根际土壤重金属、理化性质及酶活性特征

于2014年2月至2015年1月在浙江省衢州市铅锌矿附近毛竹林地采集土样,对土壤重金属含量、pH以及土壤酶活性等的动态变化特征进行了研究。结果表明:根际土与非根际土的p H在1a中变化均不明显,且变化范围都处在4.50—4.85之间;非根际土的土壤含水率大于根际土,两者的变化幅度较大,最低值均出现在6月和10月;根际土中Zn和Cd的有效态含量远高于非根际土,而Pb的有效态含量则表现出非根际土大于根际土的特点;过氧化氢酶、磷酸酶、脲酶和脱氢酶在根际土中的活性明显高于非根际土;从土壤重金属有效态与土壤酶活性相关性来看,根际土中,除有效态Pb与过氧化氢酶呈显著负相关外,其余重金属元素有效态与土壤酶活性相关性均没有显著相关性,而在非根际土壤中,有效态Cd与过氧化氢酶呈极显著负相关,与脲酶呈显著负相关,Zn和Cd则与土壤酶活性之间没有显著相关性。综合研究结果表明,毛竹根际土壤质量总体上明显优于非根际土,这为毛竹今后作为植物修复的材料提供了一定的理论依据。     

当归根际土对其种子萌发和幼苗生长的影响

室内条件下测定了当归根际土水浸液对当归种子萌发、幼苗生长的影响,采用化感作用效应指数（RI）和综合化感效应指数（M）及差异性检验评价了当归根际土的化感效应。结果表明：与蒸馏水和对照土实验组相比,根际土、非根际土水浸液对种子萌发、幼苗生长及4种酶活性均有显著的抑制作用;随着质量浓度的升高,根际土水浸液对当归种子萌发和幼苗生长的综合化感效应在各浓度（0.125～1.000 g·ml^-1）之间差异显著（P<0.05）,而在相同质量浓度条件下,根际土水浸液的综合化感效应较非根际土和对照土明显;当质量浓度均为0.500 g·ml^-1时,根际土、非根际土水浸液对4种酶活性均有明显抑制作用,且二者之间的差异达到显著水平（P<0.05）;3种土壤水浸液供体对当归种子萌发、幼苗生长的抑制强度均表现为根际土>非根际土>对照土,因此推测自毒作用是当归连作障碍的原因之一。     

病毒单糖的研究 Ⅰ.颗粒体病毒(GV)单糖的气相色谱分析

本文介绍了颗粒体病毒中单糖的气相色谱分析法,对所得病毒单糖色谱图中的主要组分进行了分析鉴定,证明组成病毒的单糖成分有:鼠李糖、核糖、木糖、甘露糖、葡萄糖和阿拉伯糖。并用相应单糖峰高比值,区分了它们间的异同。病毒单糖分析结果。能与血清学和裂解气相色谱法分析鉴定病毒的结果相符。     

裙带菜褐藻糖胶的分离纯化及其结构分析

裙带菜经水提法提取得到褐藻糖胶粗多糖,经DEAE-Sepharose FF离子交换层析和 Sepharose 4B层析后,得到Sl、S2两个单一组分,相对分子质量分别为550 808、38 335.基本结构及单糖组成分析表明,二者均含有岩藻糖、糖醛酸、硫酸基、半乳糖、甘露糖、葡萄糖、鼠李糖、木糖、阿拉伯糖,但含量差别较大,推测与二者的生理活性的差异有关.     

宁夏不同地区灵武长枣果实多糖的单糖成分分析

以宁夏4个不同地区(灵武、中宁、青铜峡、银川)成熟期的灵武长枣果实为研究对象,经水提醇沉法提取,采用DEAE-cellulose52和HW-55S分离纯化,并利用GC-MS法进行多糖的单糖组成分析。结果表明:多糖提取率最高的是灵武地区,达到1.795%;分离纯化后,4个地区的长枣多糖各得到1个中性(Ju-0)和3个酸性组分(Ju-1、Ju-2、Ju-3),其中Ju-2含量最高;GC-MS分析可知灵武长枣多糖含有阿拉伯糖、鼠李糖、核糖、岩藻糖、木糖、甘露糖、半乳糖、葡萄糖、葡萄糖醛酸、半乳糖醛酸10种单糖,不含果糖,以阿拉伯糖、核糖、半乳糖和2种糖醛酸为主,木糖含量最低。各地区多糖的单糖组成、含量各不相同,从各组分来看,四个地区多糖的Ju-0和Ju-1组分组成均以阿拉伯糖、核糖、半乳糖为主,四个地区多糖的组成差异主要在于Ju-2和Ju-3组分。从各地区单糖总量来看,灵武地区是阿拉伯糖含量最高,中宁、青铜峡、银川地区以葡萄糖醛酸含量为最高。     

Interspecific variation in bulk tissue, fatty acid and monosaccharide delta(13)C values of leaves from a mesotrophic grassland plant community

The leaves of 37 grass, herb, shrub and tree species were collected from a mesotrophic grassland to assess natural variability in bulk, fatty acid and monosaccharide delta(13)C values of leaves from one plant community. The leaf tissue mean bulk delta(13)C value was -29.3 per thousand. No significant differences between tissue bulk delta(13)C values with life form were determined (P=0.40). On average, C(16:0), C(18:2) and C(18:3) constituted 89% of leaf tissue total fatty acids, whose delta(13)C values were depleted compared to whole leaf tissues. A general interspecific (between different species) trend for fatty acids delta(13)C values was observed, i.e. delta(13)C(16:0)delta(13)C(xylose)>delta(13)C(glucose)>delta(13)C(galactose), was consistently observed. Therefore, we have shown (i) diversity in compound-specific delta(13)C values contributing to leaf bulk delta(13)C values; (ii) interspecific variability between bulk and compound-specific delta(13)C values of leaves of individual grassland species, and (iii) trends between individual fatty acid and monosaccharide delta(13)C values common to leaves of all species within one plant community.     

Comparison of carbohydrate substrate preferences in eight species of bifidobacteria

Eight species of bifidobacteria were tested for their abilities to grow on a range of monosaccharides (glucose, arabinose, xylose, galactose and mannose). In contrast to the other sugars, glucose and galactose were utilized by all species and, in general, specific growth rates were highest on these sugars. Different substrate preferences were observed between species when the bacteria were grown in the presence of all five monosaccharides. For example, glucose and xylose were coutilized by Bifidobacterium longum, whereas glucose repressed uptake of all other sugars in B. bifidum and B. catenulatum. Galactose was the preferred substrate with B. pseudolongum. In B. angulatum, glucose and galactose were utilized simultaneously. B. breve did not grow on arabinose when this sugar provided the sole source of energy. However, glucose and arabinose were preferentially taken up during growth on sugar mixtures.     

中性糖在土壤中的来源与分布特征

糖类(即碳水化合物)是土壤有机质的重要组成部分, 经生物化学降解形成不同结构的单糖。土壤中的中性单糖也叫中性糖, 主要包括木糖、核糖、阿拉伯糖、葡萄糖、半乳糖、甘露糖、岩藻糖和鼠李糖。其中, 植物来源的糖主要为五碳糖, 如木糖和阿拉伯糖; 微生物来源的糖主要包括半乳糖、甘露糖、岩藻糖、鼠李糖等六碳糖。研究中常利用六碳糖和五碳糖的比例指示微生物和植物对土壤有机碳的相对贡献。中性糖是微生物重要的碳源和能量来源, 在团聚体的形成过程中扮演着重要角色。该文整合了近30年土壤中性糖的研究进展, 对比了提取中性糖的常用方法, 分析了不同土地利用类型和不同土壤组分中中性糖的含量、来源和周转特征, 综述了影响中性糖含量和分布的主要环境因素。结果表明, 中性糖在耕地土壤中的绝对含量和相对含量均显著低于针叶林、阔叶林、草地和灌丛4种土地利用类型。(半乳糖+甘露糖)/(阿拉伯糖+木糖)(GM/AX)在不同土地利用间差异不显著, 而(鼠李糖+岩藻糖)/(阿拉伯糖+木糖)(RF/AX)则表明草地土壤中的微生物来源的中性糖含量高于针叶林和耕地。不同密度的土壤组分中, 轻质组分中中性糖的含量比重质组分高, 重质组分中微生物来源的中性糖较多; 就不同粒径(或团聚体)而言, 黏粒(或微团聚体)中微生物来源的中性糖含量更丰富。有关影响土壤中性糖含量和分布的因素的研究, 目前主要集中在人为活动(如耕种和放牧等), 而有关温度、降水等自然环境因素影响的研究较少。     

Carbohydrate utilization patterns and substrate preferences in Bacteroides thetaiotaomicron

Specific growth rates of Bacteroides thetaiotaomicron NCTC 10582 with either glucose, arabinose, mannose, galactose or xylose as sole carbon sources were 0.42/h, 0.10/h, 0.38/h, 0.38/h and 0.16/h respectively, suggesting that hexose metabolism was energetically more efficient than pentose fermentation in this bacterium. Batch culture experiments to determine whether carbohydrate utilization was controlled by substrate-induced regulatory mechanisms demonstrated that mannose inhibited uptake of glucose, galactose and arabinose, but had less effect on xylose. Arabinose and xylose were preferentially utilized at high dilution rates (D > 0.26/h) in carbon-limited continuous cultures grown on mixtures of arabinose, xylose, galactose and glucose. When mannose was also present, xylose was co-assimilated at all dilution rates. Under nitrogen-limited conditions, however, mannose repressed uptake of all sugars, showing that its effect on xylose utilization was strongly concentration dependent. Studies with individual D-ZU-14C]-labelled substrates showed that transport systems for glucose, galactose, xylose and mannose were inducible. Measurements to determine incorporation of these sugars into trichloroacetic acid-precipitable material indicated that glucose and mannose were the principal precursor monosaccharides. Xylose was only incorporated into intracellular macromolecules when it served as growth substrate. Phosphoenolpyruvate:phosphotransferase systems were not detected in preliminary experiments to elucidate the mechanisms of sugar uptake, and studies with inhibitors of carbohydrate transport showed no consistent pattern of inhibition with glucose, galactose, xylose and mannose. These results indicate the existence of a variety of different systems involved in sugar transport in B. thetaiotaomicron.     

The response of wheat straw varieties to mild sulphur dioxide treatment

Straws of five wheat cultivars, including soft and hard and dwarf and semi-dwarf varieties, were treated with sulphur dioxide (SO₂), and the effect of treatment on monosaccharide composition and cell wall (CW) degradation by rumen microorganisms was studied. Despite agrobotanical differences, the monosaccharide profiles of the straw hydrolysates were similar. Glucose, xylose, uronic acids and arabinose comprised about 98% of the total monosaccharides and the ratio of glucose to xylose was generally 2:1. The major and general effect of SO₂ treatment was expressed in solubilization of the matrix polysaccharides, cellulose being hardly affected. More than 20% of the permanganate lignin was solubilized by SO₂ in four of the cultivars. The ‘Lakhish’ cultivar had the highest lignin content (13.3%), but its lignin proved resistent to SO₂ treatment. Organic matter digestibility in vitro (IVD) was maximally increased in four varieties (excluding the ‘Lakhish’ straw) to 77–84%, and the IVD of monosaccharides to 88–93%. The treatment effect on the ‘Lakhish’ variety was weaker, the IVD of organic matter and monosaccharides was only increased to 67 and 77%, respectively. Other straw batches of the ‘Lakhish’ variety have shown a strong response to SO₂ treatment similar to that found in the straw batches of the other four cultivars. The present study provides support to previous conclusions about the major biodegradation obstacles in wheat straw. The results of this study imply that mild SO₂ treatment is generally effective in increasing the degradability of wheat straw by rumen microorganisms.     

Simultaneous assay of neutral sugars and amino sugars by an automatic sugar analyzer: applications to glycoproteins.

The simultaneous assay of neutral sugars and amino sugars commonly found in glycoproteins is described. The automatic sugar analyzer used for the determination is based on the ion-exchange chromatography of sugar-borate complexes on a strong anion-exchange resin. The sugars are identified with the orcinol/sulfuric acid reagent. While less than 40 nmol of mannose, fucose, galactose, glucose, xylose, or arabinose is sufficient for analysis at least 200 nmol mannosamine, glucosamine, or galactosamine is required; acidic monosaccharides cannot be determined. The technique of sugar analysis is applied to structural studies on natural compounds, e.g. the monosaccharide composition of lichenan and the carbohydrate moiety of the glycoproteins ovomucoid and Collocalia mucoid.     

L-lactic acid production from apple pomace by sequential hydrolysis and fermentation

The potential of apple pomace (a solid waste from cider and apple juice making factories) as a source of sugars and other compounds for fermentation was evaluated. The effect of the cellulase-to-solid ratio (CSR) and the liquor-to-solid ratio (LSR) on the kinetics of glucose and total monosaccharide generation was studied. Mathematical models suitable for reproducing and predicting the hydrolyzate composition were developed. When samples of apple pomace were subjected to enzymatic hydrolysis, the glucose and fructose present in the raw material as free monosaccharides were extracted at the beginning of the process. Using low cellulase and cellobiase charges (8.5 FPU/g-solid and 8.5 IU/g-solid, respectively), 79% of total glucan was saccharified after 12 h, leading to solutions containing up to 43.8 g monosaccharides/L (glucose, 22.8 g/L; fructose, 14.8 g/L; xylose+mannose+galactose, 2.5 g/L; arabinose+rhamnose, 2.8g/L). These results correspond to a monosaccharide/cellulase ratio of 0.06 g/FPU and to a volumetric productivity of 3.65 g of monosaccharides/L h. Liquors obtained under these conditions were used for fermentative lactic acid production with Lactobacillus rhamnosus CECT-288, leading to media containing up to 32.5 g/L of L-lactic acid after 6 h (volumetric productivity=5.41 g/L h, product yield=0.88 g/g).