麻纺韧皮纤维生物脱胶剥离体系分子生态解析及过程动力学分析

As the second important textile fibre, bast fibre from phloem of hemp plants obtains spinning ability through degumming of the pectic substances, which mainly consists of cellulose, hemicellulose and lignin. There are four degumming methods, inculding chemical, microbial, biological enzyme and chemical & biological ones. Among them, the microbial and biological enzyme methods are friendly to environment. They are coincide with National energy-saving emission reduction policies. The biological degumming also shows the advantages of quality improvement of the refined dried-ramie, without fiber injury. In fact, the microbial degumming process involves in microbial ecosystem which consists of microbial population, diversity degumming enzymes and bast fibres. In this ecosystem, the types and molecular features of bast fibres determine and have a strong influence on the characteristics and enzymes compositions of the microbial population. This proposal focuses on the studies of ramie, jute and linen microbial degumming systems. Molecular ecological and molecular biology methods are used to investigate the structure characteristics of culturable microbial population and its degumming enzymes as well as dynamics of degumming process. Because of only 1% microorganisms in natural environment being obtained their pure culture by traditional isolation and culture methods, evaluation of the diversity of microbial population only relying on microbial incubation system is limited. In order to avoid the deficiencies of traditional methods, metagenomic technology will be used to explore the diversity of uncultured microbial communities and obtain novel environmental DNA relating to new types of degumming enzymes. The aim of the project is to obtain culturable and unculturable microorganisms from natural processing ecosystem of hemp plants. Our results will provide theoretical and technical support for controllable biological degumming system with high efficiency and low cost in industry scale.

麻纺韧皮纤维是仅次于棉纤维的重要纺织纤维，必须通过脱胶脱除其中较高含量的由半纤维素、果胶和木质素等构成的胶质物、分离出纤维才具可纺性。以微生物种群及多样性脱胶酶系协同作用为基础的生物脱胶技术是其绿色环保初加工的必由之路，既符合国家节能减排政策，也是纺织工业可持续发展的不二选择。课题以苎麻、黄红麻和亚麻天然生物脱胶体系为研究对象，在充分揭示其化学组成、解剖结构特征和其中的共、附生微生物菌群基础上，利用分子生态学和分子微生物学手段，研究脱胶体系可培养微生物种群结构特征和过程动力学特点，建立动力学模型。在以脱胶关键酶系基因簇保守区为标记构建宏基因组文库基础上，筛选研究未培养微生物中蕴含的新型脱胶酶系。研究结果不仅可获得三种麻纺韧皮纤维生物脱胶体系微生物种群和酶簇结构特征和动态演替规律，还可筛选获得新型脱胶酶系，为构建麻纺韧皮纤维规模化人工可控高效生物脱胶体系提供理论和技术支持，为相关研究提供借鉴和平台。

用途广泛的麻纺韧皮纤维是仅次于棉纤维的重要纺织纤维，其可纺性通过脱胶去除其中由半纤维素、果胶和木质素等构成的胶质、分离出纤维才能得以实现。课题在苎麻、黄红麻和亚麻天然生物脱胶体系研究所获成果基础上，以我国新疆地区白麻生境为对象采样，分离筛选得到具脱胶能力微生物菌株，构建人工脱胶体系，利用分子生态学和分子微生物学技术研究构建了基于可培养微生物种群的白麻脱胶体系，建立了动力学模型。在以脱胶关键酶系基因簇保守区为标记构建宏基因组文库基础上，筛选研究未培养微生物中蕴含的新型脱胶酶系。研究结果：1）分离纯化获得可培养微生物75株，筛选得到具脱胶活性菌株10株，以形态、生理生化反应和16Sr RNA技术确定了其系统学的隶属关系；2）构建成功外源DNA总容量为1.8×105的新疆白麻生境土壤总DNA Fosmid文库，以脱胶关键酶为标志筛选得具果胶酶和木聚糖酶双酶活性阳性克隆子16个；3）利用平板拮抗实验和“加减菌”实验选择最佳微生物种类，构建白麻微生物脱胶体系，利用正交试验和响应面方法对体系pH值、浴比、接种量及转速等因素权重分析和参数优化，获知最佳工艺参数：pH6，浴比1:55，转速90 rpm。白麻纤维脱胶后残胶率为15.20 %，与理论预测值相对误差-2.50 %，误差率3.82 %，模型可靠且具参考性。以机械强度、扫描电镜、傅里叶光谱和X射线衍射等技术与传统化学脱胶分析比较，结果显示所得白麻纤维更为完整光滑；4）复合微生物脱胶体系处理白麻韧皮纤维，25 h达对数生长阶段，75 h后进入稳定期。应用Logistic模型方程，建立了白麻脱胶过程的菌群生长动力学方程，对方程进行非线性回拟合和方差分析，模型矫正决定系数R2adj=0.97055，拟合度良好。.利用微生物技术和分子生态学方法对新疆白麻生境可培养和未培养微生物菌系研究基础上，从定性和定量两个维度研究了实验室构建的白麻脱胶体系，构建了动力学方程，研究结果从理论和实践两个方面为构建规模化白麻韧皮纤维可控高效体系提供了支撑，伴随研究过程建立的平台亦为该领域的相关探索提供了借鉴。