木醋杆菌发酵产细菌纤维素的研究

【作者】 张继东；

【导师】 杨树林； 孙东平；

【作者基本信息】 南京理工大学 ， 生物化工， 2004， 硕士

【摘要】 细菌纤维素是由某些微生物高效合成而来的超微纤维网，以纯纤维素的形式存在。与自然界中的植物纤维素相比，细菌纤维素具有更优越的特性。本课题是利用木醋杆菌（Acetobacter xylinuml.1812）发酵生产细菌纤维素，优化了发酵条件，并对细菌纤维素的部分理化性质进行了研究。 通过单因素和正交试验，优化了木醋杆菌产细菌纤维素的发酵条件，包括培养基成份的优化、初始发酵条件的优化和发酵动力学参数的测定。经优化后的木醋杆菌产细菌纤维素的发酵条件为：蔗糖8％，蛋白胨1.6％，柠檬酸0.2％，Na2HPO₄0.2％，KH₂PO₄ 0.3％，MgSO₄ 0.03％，pH6.8，30℃，接种量7％，振荡培养5天，摇床转速为200r／min。 通过薄层层析和气-质联谱测得木醋杆菌发酵产物经酸或纤维素酶水解后的水解液中主要成份为葡萄糖，从而鉴定出发酵产物为细菌纤维素。通过测定细菌纤维素水解液中葡萄糖的浓度，计算出细菌纤维素的纯度为95.4％。利用红外光谱测出发酵产物中可能存在的有机化合物基团有：-OH、C-H、-CH₂、C-O等，这与标准纤维素的结构相符合。通过CP／MAS¹³C-NMR，测出了发酵产物各个碳原子的位移，这也与纤维素的标准¹³C谱相符。X-衍射测定出该细菌纤维素不含晶体。利用称重计算出纤维素湿膜的持水率为98.9％。最后，还对纤维素湿膜作了介电系数和差热分析。更多还原

【Abstract】 Bacterial cellulose is produced effectively by some microbes. It’s a super microscopic fiber net with high purity. The character of bacterial cellulose is more superior than botanical cellulose. This dissertation is on the producing bacterial cellulose with Acetobacter xylinuml.1812. The fermentation condition of Acetobacter xylinuml.1812 has been optimized . Some physical and chemical characters of bacterial cellulose have been studied.The fermentation condition of Acetobacter xylinuml.1812 has been optimized by single factor and orthogonal experiments including the components of medium and the initial fermentation condition and the fermentation parameters. The fermentation condition is 8% sucrose, 1.6% peptone, 0.2% citric acid, 0.2% Na2HPO4, 0.3% KH2PO4, 0.03% MgSO4, pH 6.8, 30, 7% inoculation amount, agitating culture at 200r/min for 5 days.The fermentation product of Acetobacter xylinuml.1812 was hydrolyzed by acid or cellulase, then it was proved that there was glucose in the hydrolyte by TLC and chromatography mass spectrometry, thereby the product was identified as bacterial cellulose. The purity of bacterial cellulose is 95.4% by determining the glucose’s content of the hydrolyte of the cellulose. With infrared absorbing analysis method, it was determined that there were some organic compound radicals which were -OH, CH,-CH2, C-O in the structure of the fermentation product. The result accorded with the structure of standard cellulose. The bit shifts of the carbon of the fermentation product were determined by CP/MAS13CNMR, the result accorded with the 13C standard spectrum too. This bacterial cellulose was proved that it did not include crystal by X-ray diffractometry. The water-holding ratio of the wet membrane of bacterial cellulose is 98.9% by weight method. At last, the wet membrane of bacterial cellulose was determined by dielectric constant and DTA.更多还原