玉米秸秆纤维素提取及半纤维素与木质素脱除工艺探讨

为了获取优质的纤维素,以玉米秸秆为原料,通过对纤维素提取工艺的探讨,确定了既能保持纤维素提取量,又可较多脱除半纤维素和木质素的工艺条件。试验结果表明,在NaOH溶液的质量分数为5%、反应温度为55℃、反应时间为1.5 h条件下,半纤维素的脱除率达到92.82%;在NaClO2溶液浓度为9.5 g/L、处理温度75℃条件下,木质素脱除率达到64.32 %。在此工艺条件下,玉米秸秆纤维素含量达到70.12%。     

MALDI-MS技术在木质素类物质结构研究中的应用进展

列举了基质辅助激光解吸附质谱(MALDI - MS)技术在木质素研究中的应用,这种新的技术可以提供对木质素结构的新认识,同时也可以对木质素生物降解过程中的相关蛋白质进行研究.     

低游离甲醛羟甲基化木质素磺酸盐-酚醛复合胶黏剂研究

以工业木质素为原料,采用羟甲基化反应提高木质素反应活性,确定了羟甲基化反应木质素和催化剂的最佳配比:木质素与甲醛质量比为3:1、催化剂用量为0.25%(以木质素原料计).并用FT-IR和13C NMR对羟甲基化反应结果进行了分析.通过羟甲基化木质素磺酸盐(HLF)与酚醛树脂(PF)共混制得木质素酚醛树脂(LPF)胶黏剂.实验结果表明,该胶具有制备工艺简单、游离甲醛低的特点,用HLF替代40%的PF时,其胶合强度达到国家Ⅰ类胶合板的要求.     

欧美杨107木质素生物合成酶CCR基因的克隆及其鉴定

木质素作为草类饲料消化性的限制因子,直接影响饲料的利用率,而CCR是木质素生物合成关键酶之一。从正在分化的2a生欧美杨107次生木质部RT-PCR扩增出的基因片段,与pMD20-T载体连接,重组质粒经限制性内切酶酶切、特异引物PCR扩增和测序鉴定。结果表明该扩增片段长为961bp,含一个编码301氨基酸的完整开放阅读框,其核苷酸序列与Leple等发表的白杨杂种Populus trichocarpa CCR的cDNA序列(AJ224986)同源性达到98.2%,并且反向插入到pMD20-T载体,因此构建了CCR的反义大肠杆菌表达载体,为后续的基因操作打下基础。该基因序列已提交国际核苷酸序列库,登录号为AM921698。     

不同微生物菌剂对甘蔗滤泥腐解效果的影响

采用室内模拟堆肥的方法,研究了3组不同的微生物复合菌剂对甘蔗滤泥腐解效果的影响。结果表明,HM发酵基、SQ复合菌和有机废弃物快腐微生物菌剂能加速甘蔗滤泥的腐熟和提高甘蔗滤泥中木质素、纤维素和半纤维素的降解率。堆肥25d后,经HM发酵基、SQ复合菌和有机废弃物快腐微生物菌剂处理的滤泥的T值降到了0.6,木质素的降解率分别比不接种微生物菌剂的对照处理提高了45.46%、39.95%、64.77%,纤维素的降解率分别提高了35.58%、36.34%、36.59%,半纤维素的降解率分别提高了27.87%、28.98%、30.78%。     

秸秆利用中白腐真菌的作用研究

对白腐真菌木质素降解酶系统进行评述。阐述利用白腐真菌和其他微生物进行混菌发酵,既可以降解秸秆中的木质素,又可以提高发酵后饲料中蛋白质的含量。白腐真菌中的食用真菌发酵秸秆后,菌糠可以作为反刍动物的优质饲料。     

Chemistry of soil organic matter as related to C : N in Norway spruce forest (Picea abies(L.) Karst.) floors and mineral soils

Due to high nitrogen deposition in central Europe, the C : N ratio of litter and the forest floor has narrowed in the past. This may cause changes in the chemical composition of the soil organic matter. Here we investigate the composition of organic matter in Oh and A horizons of 15 Norway spruce soils with a wide range of C : N ratios. Samples are analyzed with solid‐state ¹³C nuclear magnetic resonance (NMR) spectroscopy, along with chemolytic analyses of lignin, polysaccharides, and amino acid‐N. The data are investigated for functional relationships between C, N contents and C : N ratios by structural analysis. With increasing N content, the concentration of lignin decreases in the Oh horizons, but increases in the A horizons. A negative effect of N on lignin degradation is observed in the mineral soil, but not in the humus layer. In the A horizons non‐phenolic aromatic C compounds accumulate, especially at low N values. At high N levels, N is preferentially incorporated into the amino acid fraction and only to a smaller extent into the non‐hydrolyzable N fraction. High total N concentrations are associated with a higher relative contribution of organic matter of microbial origin.     

Priming effects of sugars,amino acids,organic acids and catechol on the mineralization of lignin and peat

The ¹⁴C‐labeled substrates glucose, fructose, alanine, glycine, oxalic acid, acetic acid, and catechol were incubated at 20 °C in a model system that consisted of sand mixed with lignin or peat (3 % C_org). Each substrate was added at either 80 or 400 μg C (g sand)^—1. During 26 days of incubation with an inoculum extracted from forest soil, the amount of CO₂ evolved was measured hourly. The amount of ¹⁴CO₂ was determined after 4, 6, 12, 19, and 26 days. After 26 days of incubation, each substrate showed priming effects, but not in all examined treatments. Most substrates stimulated the degradation of the model substances (positive priming effects). Negative priming effects only were found in the lignin system with oxalic acid and catechol addition at both concentrations. The strongest positive priming occurred in the peat system with the oxalic acid addition of 80 μg C g^—1 where 1.8 % of the peat were mineralized after 26 days, compared to 0.7 % in the control. The addition of 400 μg alanine‐C g^—1 caused the strongest increase in lignin mineralization, amounting to 3.9 % compared to 2.8 % in the control. During the incubation the extent of priming changed with time. Most substrates caused the strongest effects during the first 4 to 10 days of incubation. The extent of priming depended on substrate type, substrate concentration, and organic model substance. Possibly this is due to the activation of different microorganisms.     

Hydrolysis lignin as a multifunctional additive in Atlantic salmon feed improves fish growth performance and pellet quality and shifts gut microbiome

The objective of this study was to evaluate hydrolysis lignin (H‐lignin), derived from wood biomass, as a multifunctional component of aquafeeds. Atlantic salmon (28.8 ± 1.1 g) were fed diets for 16 weeks, which included two H‐lignin types (HL1 and HL2) at 15, 30 or 50 g/kg (wt/wt) or a control diet (no added H‐lignin). HL1 was extracted with water such that no soluble sugar and oligosaccharides remain, while HL2 contains a higher fraction of water‐soluble sugars and oligosaccharides. Pellet durability and density were measured. After 16 weeks, salmon were measured for weight and length, and whole carcass, hindgut and digesta contents were sampled. Pellet durability increased from the control to 30 g/kg H‐lignin but decreased at 50 g/kg. Salmon fed diets with HL1 at 15 and 30 g/kg showed higher weight gain and lower feed conversion ratio compared with salmon fed the control diet and 50 g/kg HL1. There were no significant differences in whole‐body composition or intestinal morphology. Microbial characterization (16S) revealed lower abundance of Proteobacteria, higher abundance of Mycoplasmataceae and increasing Lactobacillaceae abundance with higher HL1 inclusion. This study demonstrates that HL1 (at 15 and 30 g/kg) shows potential as a functional feed additive for salmon.     

柑橘果实枯水的生理及分子机制研究进展

枯水是一种柑橘果实生理性病害,引起柑橘的汁胞硬化、果汁减少、糖酸物质丧失,严重影响果实的食用价值和商品价值。本文从细胞学、品质营养、激素水平、酶活性和分子生物学等方面阐述了柑橘果实枯水发生的生理和分子机制,旨在为后期深入开展柑橘果实枯水机制和防治措施的研究奠定基础。