细菌纤维素菌株超高压诱变选育及其发酵培养基的优化

 为了获得高产细菌纤维素菌株，对初选的细菌纤维素菌株J₂进行超高压诱变，运用Plackett-Burman设计对影响高压诱变菌株生产细菌纤维素的因素效应进行评价，采用Box-Behnken试验优化发酵培养基组成。试验结果表明，超高压诱变压力、时间对细菌纤维素菌株有显著或极显著影响。细菌纤维素菌株高压诱变条件为压力250 MPa、时间15 min、温度25 ℃。经超高压诱变，获得产纤维素能力高、遗传稳定性好的诱变菌株M₄₃₈。影响诱变菌株M₄₃₈发酵生产细菌纤维素的关键因子是酵母浸出汁、MgSO₄和无水乙醇。优化的发酵培养基为碳源5%（葡萄糖∶蔗糖为4∶1）、酵母浸出汁1.25%、CaCl₂0 15%、ZnSO₄ 0.20%、K₂HPO₄ 0.20%、MgSO₄ 0.93%、富马酸0.30%、无水乙醇0.50%。利用此培养基培养诱变细菌纤维素菌株M₄₃₈，其纤维素产量是优化前的1.84倍，是超高压诱变之前的2.69倍。超高压技术用于细菌纤维素菌株的诱变育种是可行的。发酵培养基的优化可显著提高菌株M₄₃₈发酵生产细菌纤维素的能力。

Breeding of Bacterial Cellulose Strain Induced by Ultra-High Pressure and Optimization of Fermentation Medium

In order to obtain high-yield strains of bacterial cellulose (BC), the primary bacterial cellulose strain was induced by ultra-high pressure. Plackett-Burman design was employed to evaluate variables which were relevant to yield of BC which was produced by strain induced by ultra-high pressure. Fermentation medium composition was optimized through Box-Behnken experiment. The results show that mutagenic pressure and time on the strain of bacterial cellulose have significant or extremely significant influence. The mutagenic conditions of BC strain are pressure of 250 MPa, time of 15 min, and temperature of 25 ℃. The mutagenic strain M₄₃₈ with high cellulose production capacity and genetic stability is obtained through the ultra-high pressure treatment. The key factors affected bacterial cellulose production of mutation strain M₄₃₈ are yeast juice, MgSO₄, and anhydrous ethanol. The optimistic fermentation medium is as follows, carbon source 5% (glucose∶sucrose=4∶1), yeast juice 1.25%, CaCl₂ 0.15%, ZnSO₄ 0.2%, K₂HPO₄ 0.2%, MgSO₄ 0.93%, fumaric acid 0.3%, and ethanol 0.5%. BC yield of M₄₃₈ cultured with optimized fermentation medium is as 1.84 times as that cultured with the initial fermentation medium, and is as 2.69 times as that of the unmutant strain. Ultra-high pressure technology for mutation breeding of bacterial cellulose strain is feasible. BC producing capacity of M₄₃₈ can be significantly improved through fermentation medium optimization.