惰性吸附载体固态发酵细菌纤维素的研究
文献类型：学位论文
| 作者 | 翁媛媛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2010-06-07 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 陈洪章 |
| 关键词 | 细菌纤维素 惰性载体 固态发酵 聚氨酯塑料泡沫 汽爆玉米秸秆 |
| 其他题名 | Procuction of bacterial cellulose by solid state fermentation on inert support |
| 学位专业 | 生物化工 |
| 中文摘要 | 细菌纤维素（bacterial cellulose, BC）是由一定的微生物（主要为细菌）产生的细胞外纤维素，目前在工业生产中细菌纤维素的培养方法大致分为液态静置培养和动态培养法。然而，静态培养过程中由于纤维素的形成会限制氧的有效传递,从而进一步限制了纤维素的合成。动态发酵过程中，受剪切力的影响，菌体易向不产细菌纤维素的方向突变，从而降低产量。针对上述问题，以聚氨酯塑料泡沫为吸附载体，对木醋杆菌（Acetobacter xylinum）吸附载体固态发酵过程中影响纤维素产量的因素及其发酵过程进行了初步研究。结果表明在固液比为1：16，载体颗粒大小小于1.25 cm，载体堆料高度为3 cm，初始葡萄糖浓度为20 g/L时，72 h发酵，细菌纤维素产量达到4.86 g/L，整个发酵周期的容积生产率达到1.62 g/L•d。与常规液态静置发酵相比，发酵产量同期提高了5.65倍，一个发酵周期的容积生产率提高了3.16倍。通过与液态静置发酵和摇瓶发酵的对比试验，发现由于溶氧限制，当初始碳源浓度提高时两种液态发酵方式均不能促进细菌纤维素产量的提高，而吸附载体固态发酵的引入在一定程度上改善了碳源利用率低的问题，且产物具有更细的显微结构，且组成和结构上没有变化。此外还进一步利用压力脉动固态发酵装置进一步促进了传质，使产物产量提高了7.8%。细菌纤维素作为一种工业生产中具有巨大商业前景的多糖聚合物，若能以低成本、来源广泛的生物质资源为出发原料,进行大规模生产,则可作为一种高附加值的生物基材料得到应用。论文对汽爆秸秆酶解液发酵Acetobacter xylinum产细菌纤维素的可发酵性能进行了初步考察。由于汽爆秸秆酶解液中有机酸含量高，考察了发酵培养基的初始pH值对产物生成量的影响，发现当pH为6.3～6.5时获得最大的细菌纤维素产量。汽爆秸秆酶解液对于Acetobacter xylinum的菌体生长和产物积累并没有抑制作用，通过对照试验发现其产物产量提高了91%且发酵过程的pH值降低幅度小于以葡萄糖为碳源的合成培养基，说明汽爆秸秆酶解液对于发酵生产细菌纤维素是一种有价值的替代碳源。 |
| 英文摘要 | Bacterial cellulose (BC) is one of the most promising nanostructured biomaterial, displaying unique properties with a broad perspective for application in different fields, including composite membranes, medicine, artificial skins, blood vessels, and binding agents。Now the most common cultivation methods in the industrial level for bacterial cellulose production are the static fermentation and the agitated fermentation. While in the static fermentation there is no efficient O2, in the agitate fermentation the Acetobacter xylinum is converted to Cel-. To avoid the problems existing in the traditional ways for the BC production, a novel solid state fermentation system was introduced. Growth and bacterial cellulose(BC) production of Acetobacter xylinum on PUF (polyurethane foam), which serves as an inert support, was studied under different conditions, including the ratio of culture medium to PUF cubes, bed depth and initial glucose concentration. Maximal productivity of bacterial cellulose was obtained at the condition of 16 mL medium per g PUF cubes, 3 cm bed depth, the side length of the tube less than 1.25 cm and glucose concentration of 20 g/L. After 72 h fermentation, the concentration of bacterial cellulose comes to 4.86 g/L, which amounts to 6.65 times compared with that of submerged fermentation(SMF). When the initial carbon resource increased, the productivity of BC arrived from SSF on inert support could be increased to some extend, while in the SMF, the production of BC could not increased accordingly. Besides, air pressure pulsation, which could enhance the mass and heat transfer, was performed in the bacterial cellulose production and the productivity of BC was further increased by 7.8%. Maize straw is a kind of abundant renewable resource. If bacterial cellulose, which serves as a promising polysaccharides in industry, could be produced from inexpensive and abundance biomass resources, it would be utilized as a value-added bio-based material economically. In the experiment, steam-exploded straw was used as carbon source. The result shows that the weak acids, furan derivatives and phenolic substances in the hydrolysate, which recognize as the main inhibitor to the fermentation, didn’t show the inhibition effect for the growth of Acetobacter xylinum and bacterial cellulose production. It indicated that the maize straw is a potential feedstock for the large-scale production of BC, as well as the steam-explode is a feasible pretreatment methods in the efficient utilization of maize straw for process of BC production. |
| 语种 | 中文 |
| 公开日期 | 2013-09-17 |
| 页码 | 81 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1501]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 翁媛媛. 惰性吸附载体固态发酵细菌纤维素的研究[D]. 中国科学院研究生院. 2010. |
入库方式： OAI收割
来源：过程工程研究所
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