搅拌桨组合与葡萄糖流加工艺相结合的凝胶多糖发酵工艺优化

Optimization of Curdlan Fermentation Process by Combining Impeller Combinations and Glucose Fed-Batch Modes

考察了利用葡萄糖作为碳源底物时,不同的葡萄糖添加模式(批次加入、脉冲式流加和连续流加)和搅拌桨组合模式(三层桨均为六平叶径流桨3RT、底层桨为六平叶轮径流桨和上层桨为椭圆桨RT+E)对凝胶多糖发酵过程代谢特性的影响.实验结果表明,葡萄糖为批次加入时,菌体的呼吸代谢强度受到明显抑制,凝胶多糖产量只有25.12 g/L;通过葡萄糖脉冲式流加和连续流加策略控制发酵罐中葡萄糖质量浓度为20 g/L左右,可以降低高质量浓度葡萄糖对凝胶多糖合成的抑制作用,凝胶多糖的产量提高到33.88 g/L;通过优化桨型组合为RT+E可以增强葡萄糖流加过程中发酵液内部的混合过程,凝胶多糖产量提高至36.10 g/L,最终优化后葡萄糖合成凝胶多糖的产量增加了44.40%.

Curdlan has been widely applied in food, medicine, and aquaculture due to its unique gelation and immune-enhancing properties. Curdlan is mainly produced by microorganism fermentation in order to meet the market demand. The curdlan fermentation broth is a kind of highly viscous fluid, and the viscosity increases significantly with the curdlan accumulation during fermentation process, resulting in poor mixing and mass transfer efficiency and subsequently limiting the biosynthesis of curdlan. This study investigated the effects of glucose control modes (batch, pulse fed-batch, continuous fed-batch) and impeller combination types (triple Rushton turbines (3RT), bottom Rushton turbines combined with upper Ellipse (RT+E)) on the metabolic characteristics of curdlan fermentation using glucose as a carbon source for the biosynthesis of curdlan. The results showed that the curdlan biosynthesis of Alcaligenes faecalis was significantly inhibited at the initial higher glucose concentration in batch fermentation, and the yield of curdlan was 25.00 g/L. The inhibition effect on the curdlan biosynthesis of Alcaligenes faecalis led by high glucose concentration could be remarkably reduced by using a continuous fed-batch strategy with a concentration of the glucose at around 20 g/L, and the yield of curdlan was enhanced to 33.88 g/L. In addition, the RT+E combination was demonstrated to be an effective approach for reducing the mixing time of the fermentation broth. Finally, the yield of curdlan could be further increased to 36.10 g/L, leading to a 44.40 % increase compared to that obtained in batch fermentation.