真空膜蒸馏耦合能源植物酶解发酵制乙醇基础研究

Jerusalem Artichoke (JA), referred to as an energy plant, is appropriate for planting in the desert regions, beaches, and saline and alkaline wastelands. And in our country, major breakthroughs have been made in the selection and breeding of salt-tolerant types of JA and the planting in beaches. This proposal has put forward the ethanol production from JA raw powders by a novel membrane bioreactors (MDBRs) coupling in situ separation of VMD with enzymatic hydrolysis and fermentation processes. The research focuses primarily on the solutions to the key scientific problem, poor conversion efficiency of biomass, which results from the products (saccharides, enthanol) inhibition, and to the technical bottleneck problem, the low productivity and high energy consumption of process. First, the optimal conditions for the production of inulinase from yeast Kluyveromyces kl-lnu strains will be experimentally studied. Then, the production kinetics of ethanol from JA by simultaneous enzymatic hydrolysis and fermentation will be investigated. And predominant strains of Saccharomyces cerevisiae will be selectively cultivated. Furthermore, MDBRs will be employed to produce ethanol. Our proposal will study systematically the mechanisms by which the operating modes, operating conditions, and membrane materials of VMD in situ separation unit promote the biomass conversion rate and the yield of ethanol. Finally, the key processes with efficient and energy saving to produce ethanol and matched conditions will be achieved. And a mathematical model which can describe the dynamic acts of this complex system will be developed. The research results will supply the relevant basic data, experimental technologies, and scientific theory as guideline for pilot process and further investigation, and establish scientific base of converting energy plants into ethanol production with high-efficiency.

糖基能源植物菊芋适于沙漠、滩涂、盐碱荒地种植，且我国在耐盐菊芋品种选育及滩涂种植方面已有重要突破。本项目提出以菊芋粗粉酶解-发酵耦合真空膜蒸馏（VMD）原位分离的新型膜生物反应器（MDBRs）制备乙醇，着重研究解决生物质转化过程产物（糖、醇）抑制导致转化效率低的关键科学问题，以及由此引起设备效率低、能耗高的技术瓶颈问题。首先，实验研究克鲁维酵母kl-lnu高效代谢产菊粉酶最适条件；然后，研究同步酶解-发酵产乙醇动力学，并筛培酿酒酵母优势菌株；进而，以MDBRs制备乙醇，系统研究VMD原位分离乙醇单元的操作模式、操作条件以及不同膜材料等对生物质转化速率和产醇收率的促进机制。最终，获得MDBRs高效节能制备乙醇的关键工艺和匹配条件，并建立起描述这一复杂体系动力学行为的数学模型，以期为中试规模工艺设计和进一步研究提供相关基础数据、实验技术和科学理论指导，奠定能源植物高效转化为乙醇产品的科学基础。

本项目以菊芋粗粉酶解-发酵耦合真空膜蒸馏（VMD）原位分离的新型膜生物反应器（MDBRs）制备乙醇，着重研究解决生物质转化过程产物（糖、醇）抑制导致转化效率低的关键科学问题，以及由此引起设备效率低、能耗高的技术瓶颈问题。本项目获得以下主要研究成果：.基于酿酒酵母抗氧化防御体系，对酿酒酵母内不同抗氧化蛋白进行挖掘，并与调控元件—酿酒酵母自身强组成型启动子FBA1p进行组装，提高了酿酒酵母菌株生物活力。探究了克鲁维酵母的生长及产菊粉酶特性，获得了克鲁维酵母在膜生物反应器中生长产酶的规律。.对菊粉及菊芋水解机理进行理论分析的基础上，基于米氏方程，建立与阿伦尼乌斯方程耦合的水解动力学模型，实验验证了模型可靠性。.研究了在菊芋培养基中克鲁维酵母培养直接水解菊芋的可行性，省去了酵母扩培产酶步骤，即利用菊芋代替传统培养基，供给克鲁维酵母生长代谢所需营养，将克酵母产酶和菊芋水解两个过程耦合，实现了一种不断供给新鲜菊粉酶的水解工艺，还原糖生产时长由72h以上缩短至24h，并优化接种方法获得高于86%的水解率。.系统研究了菊芋分步水解-发酵及同步水解-发酵两种工艺的物质总转化率和产醇速率，证实了由于产物抑制，水解和发酵两个过程耦合并不能缩短反应时间并提高产醇率。.以菊芋为原料，研究了产酶-水解-发酵“三耦合工艺”制乙醇，该工艺中不断有新酶产生，改善了因发酵产物乙醇对菊粉酶抑制作用引起水解速率下降的问题，缩短了乙醇生产周期，产率得到提高。在此基础上，将真空膜蒸馏（VMD）分离过程与产酶-水解-发酵体系耦合，实现了最终产物乙醇的原位分离，体系的乙醇收率高达98.9%，产乙醇周期由传统分步工艺的100小时左右缩短至34小时。.应用之前完成的基金项目（20976024）的研究成果，对PVDF膜表面进行疏水改性，赋予PVDF膜超疏水特性，另方面，采用非溶剂致相分离法，在PTFE微孔基膜表面上构建PVDF微纳米颗粒状结构，提高膜表面的粗糙度，赋予膜超疏水特性。分别制备了两种分离膜，后者在88kPa真空度下，分离因子从基膜的5.6提高到10.1，且性能稳定。.项目所构建的利用菊芋产醇“四耦合工艺”，无生物营养基和化学物质添加，且制备全程无污染，是一种高效清洁制备技术，有应用前景。此外，申请专利5项（授权3项），发表SCI论文5篇、另有5篇整理撰写中，培养研究生8名。