产细菌纤维素菌株选育及细菌纤维素性质研究

【作者】 朱明阳；

【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】 细菌纤维素是一种由微生物合成的超微纯纤维素，与自然界中存在的植物纤维素相比，具有纯度高、结晶度高和重合度高，吸水性强，抗张强度好，生物适应性强，可在自然界直接降解等独特的性质。利用微生物发酵生产细菌纤维素，并将其应用于食品、医药、造纸和生物医学工程等领域，具有广泛应用前景，是当今生物材料研究的热点之一。 本文首先从菌种筛选着手，从腐败水果中筛选到一株产细菌纤维素菌株，命名为NUST⁰³¹，通过形态特征观察、生理生化特征试验和醌类分析，对其进行种属鉴定，鉴定结果为醋化醋杆菌属。接着对该菌株进行了紫外诱变和紫外线-氯化锂复合诱变，使细菌纤维素产量得到一定提高。同时对该菌株作了培养条件优化，确定了最佳碳源、氮源和初始pH值。测定了发酵过程中的残糖、残氮、pH和细菌纤维素产量的变化趋势。产物进行红外光谱分析表明：在1047cm^-1处的吸收峰，是由碳氧键的伸缩振动引起的，是纤维素分子的特征峰：在3365 cm^-1处的吸收峰，反映了O-H键的伸缩振动；在约900cm^-1的吸收峰是糖苷键的特征峰。对酸水解物乙酰化后进行GC-MS分析，与Glc糖醇乙酸酯的标准谱图对照，根据两个质谱图中的特征峰几乎完全相同，证明乙酰化产物为Glc糖醇乙酸酯，说明酸水解物中有葡萄糖组分，从而证明酸水解物为纤维素。用透射电镜分析，表明细菌纤维素是由微纤维束相互缠绕形成的网状结构，并有分形现象出现。利用酶水解法分析纤维素纯度，其纯度为95.6％。并用称重法分析了细菌纤维素的持水性能，其持水率为98.03％，表明其具有高度亲水性。更多还原

【Abstract】 Bacterial cellulose(BC), synthesized by some microbes, is a kind of ultra-fine and highly pure fiber. And in comparison with other high plant cellulose in nature, BC displays unique properties, including higher purity, higher crystallinity, higher degree of polymerization, higher water absorption capacity, higher tensile strength, stronger bioadadptability and BC can be decomposed directly in natural environment. BC produced by microorganisms has extensive commercial applications. To date, it has been applied in many field of such as food, medical ,paper etc.A bacterial cellulose-producing strain NUST031 was selected by screening some strains from rotten fruits. The morphological features and physiological and biochemical characteristics of strain are examined and tested by the analysis of quinone. Strain NUST031 was preliminarily identified as Acetobacter aceti subsp. The cellulose-producing strain was mutagenized by ultraviolet rays(UV) and UV-LiCl. It was found that much higher cellulose accumulation was obtained by these mutants. The optimum production condition of BC such as carbon source, nitrogen source and primary pH was determined. As far as strain NUST031 was concerned, the typical dynamics of cellulose synthesis during culture was experimented and measured such as glucose and nitrogen utilization and pH in comparison with product’s yield. The structural features of product was preliminarily determined by IR. The intensity of the band at 1047cm-1 indicates C-O vibration. A broad peak around 3365 cm-1was shown for O-H vibration and the band around 900cm" conforms the presense of β ,1-4 linkages. The product of acid hydrolysis was proved to be glucose by GC-MS, thus the results indicated that product was bacterial cellulose. The purity of the cellulose was determined by cellulase hydrolysis. Its degree of purity was 95.6%. The water-holding capacity of BC was 98.03%. It was seen that BC had high water absorption capacity.更多还原