Enzymes in Bast Fibrous Plant Processing

The program COST Action 847 Textile Quality and Biotechnology (2000–2005) has given an excellent chance to review the possibilities of the research, aiming at development of the industrial application of enzymes for bast fibrous plant degumming and primary processing. The recent advancements in enzymatic processing of bast fibrous plants (flax, hemp, jute, ramie and alike plants) and related textiles are given. The performance of enzymes in degumming, modification of bast fibres, roving, yarn, related fabrics as well as enzymatic bonding of lignocellulosic composites is provided.     

我国麻类作物种质资源保护与利用研究进展

总结了我国麻类种质资源在收集保存、繁殖更新、鉴定评价和分发利用等方面的最新进展.10年来,新增麻类种质697份,保存资源数量增至9764份,居世界第1位;繁殖更新麻类资源5343份次,基本解决了麻类资源安全保存和供种等问题;完成农艺性状、经济性状及特性鉴定6543份次,筛选出麻类优异种质296份;向全国50家单位分发种质4296份次,资源利用效率大幅提高.并针对当前存在的问题,提出了下一步工作的明确目标和任务.     

我国麻类资源的多样性及其保护利用对策

在“七五”、“八五”、“九五”研究的基础上,本文论述了我国麻类资源的种类、数量与分布以及保护利用现状等方面的问题,并提出了多样性的可持续发展和利用对策,为今后我国麻类资源的收集、保存、鉴定、创新和利用提供依据。     

Lignification in the flax stem: evidence for an unusual lignin in bast fibers

In the context of our research on cell wall formation and maturation in flax (Linum usitatissimum L) bast fibers, we (1) confirmed the presence of lignin in bast fibers and (2) quantified and characterized the chemical nature of this lignin at two developmental stages. Histochemical methods (Weisner and Maüle reagents and KMnO₄-staining) indicating the presence of lignin in bast fibers at the light and electron microscope levels were confirmed by chemical analyses (acetyl bromide). In general, the lignin content in flax bast fibers varied between 1.5% and 4.2% of the dry cell wall residues (CWRs) as compared to values varying between 23.7% and 31.4% in flax xylem tissues. Immunological and chemical analyses (thioacidolysis and nitrobenzene oxidation) indicated that both flax xylem- and bast fiber-lignins were rich in guaiacyl (G) units with S/G values inferior to 0.5. In bast fibers, the highly sensitive immunological probes allowed the detection of condensed guaiacyl-type (G) lignins in the middle lamella, cell wall junctions, and in the S1 layer of the secondary wall. In addition, lower quantities of mixed guaiacyl–syringyl (GS) lignins could be detected throughout the secondary cell wall. Chemical analyses suggested that flax bast-fiber lignin is more condensed than the corresponding xylem lignin. In addition, H units represented up to 25% of the monomers released from bast-fiber lignin as opposed to a value of 1% for the corresponding xylem tissue. Such an observation indicates that the structure of flax bast-fiber lignin is significantly different from that of the more typical woody plant lignin, thereby suggesting that flax bast fibers represent an interesting system for studying an unusual lignification process.     

Expression and thermostability of Paenibacillus campinasensis BL11 pectate lyase and its applications in bast fibre processing

An open reading frame (ORF) with 963 nucleotides from Paenibacillus campinasensis BL11 was cloned and expressed in Escherichia coli. It encodes a pectate lyase (EC 4.2.2.2) of 35.6 kDa, denominated Pel‐BL11. The recombinant Pel‐BL11 was fused with His‐tag and purified. An optimal activity of 1623 IU mg^?1 was exhibited at 50°C, pH 10. Significant activities of Pel‐BL11 are demonstrated between 40 and 70°C and from a pH of 7–11. The observed half‐lives are 103 min at 70°C and 288 min at 40°C. Compared to other published acid and alkaline pectate lyases, Pel‐BL11 demonstrated exceptional thermostability and wider pH adaptability. Temperature effects on the cleavage of the pectate α‐1,4‐glycosidic bond by Pel‐BL11 were examined. Continuous cleavage occurred for the first 3 h at 30 and 50°C. However, at 70°C, the majority of the cleavage occurred during the first 10 min. Weight loss in gampi and paper mulberry fibres after enzyme treatment validate the potential of this treatment in fibre degumming.     

麻类脱胶高效菌株果胶裂解酶基因克隆与表达

【目的】克隆麻类脱胶高效菌株Dickeya sp.DCE-01的果胶裂解酶基因并进行原核表达,对表达产物进行纯化和酶学性质研究。【方法】根据该菌株全基因组序列预测的果胶裂解酶基因Q59419设计引物,PCR扩增后将该基因连接到pEASY-E1和pACYCDuet-1载体上,导入E.coli BL21(DE3)进行表达。选择酶活力高的阳性克隆子进行大量诱导表达后,采用超滤和Sephadex G-100凝胶层析两步法纯化出果胶裂解酶,研究其酶学性质。【结果】克隆到果胶裂解酶基因pel(GenBank登录号:JX964997),其序列全长1 128 bp,编码375个氨基酸。pACYCDuet-1-pel-BL表达胞外果胶裂解酶活力最高,发酵液粗酶活达298.8 IU/mL。其最适反应温度为50°C,最适pH为9.0;保温1 h,酶活稳定温度≤45°C,稳定pH为9.0?10.0。酶催化作用依赖于Ca2+,其最适作用浓度为2 mmol/L;Zn2+、Ca2+和NH4+促进酶活力,Fe3+和Pb2+严重抑制酶活力;聚半乳糖醛酸钠为该酶的最适底物。【结论】从麻类脱胶高效菌株中发掘到碱性果胶裂解酶基因,其表达产物在生物质加工过程中具有重要工业化应用前景。     

麻类作物组织培养及遗传转化研究进展

概述了国内外红麻等麻类作物快速繁殖、花药培养、原生质体培养、体细胞胚发生、器官发生等几个方面的组织培养以及遗传转化的研究进展,并对存在的问题进行了讨论,提出了进一步研究的一些见解,以期为促进麻类组织培养及遗传转化研究提供科学依据。