细菌纤维素发酵培养基的优化及超微观结构分析

为了提高细菌纤维素的产量, 本研究对一株氧化葡糖杆菌菌株J2液体发酵生产细菌纤维素的培养基进行了优化, 并对其代谢的细菌纤维的超微观结构进行了观察。运用Plackett-Burman试验设计法对8个相关影响因素的效应进行了评价, 筛选出了有显著效应的3个因素: 酵母膏、ZnSO4、无水乙醇, 其他5个因素的影响未达到显著水平(P>0.05)。然后采用Box-Behnken的中心组合试验设计和响应面分析方法(RSM)确定了上述三个因素的最佳浓度, 并且以棉纤维为对照, 运用扫描电镜观察了细菌纤维素的超微观结构, 结果表明: 菌株J2利用优化后的发酵培养基生产细菌纤维素的产量为11.52 g/100 mL, 是优化前的1.35倍, 电镜照片显示细菌纤维素微纤维丝直径<0.1 mm, 比棉纤维细很多, NaOH处理可以除去纤维网络结构中的菌体。

Optimization of Bacterial Cellulose Fermentation Medium and Observation of Bacterial Cellulose Ultra-micro-structure

In order to improve the yield of bacterial cellulose (BC), the fermentation medium of BC-producing strain J2 (Gluconobacter) was optimized, and BC ultra-micro-structure was observed. Initially, Plackett-Burman design was employed to evaluate eight variables which were relevant to BC production. Three statistically significant parameters including yeast extract, ZnSO4, ethanol were selected and other 5 variables were not significant (P>0.05). The optimized levels of three variables were defined by Box-Behnken design and response surface methodology (RSM). BC ultra-micro-structure was observed by scanning electron microscope (SEM) with cotton cellulose as comparison. The results indicated that the BC yield under the optimum fermentation medium was 11.52 g/100 mL, which was as 1.35 times as that under the original fermentation medium. The SEM photos manifested that bacterial cellulose ribbon, with a diameter less than 0.1 mm, was less than cotton cellulose ribbon. The bacteria inside the cellulose net were eliminated after the NaOH treatment.