Abstract An internal fibrous bed bioreactor (IFBB) was constructed in an anaerobic stirred fermenter for butyric acid production by immobilized Clostridium tyrobutyricum ATCC 25755. In the IFBB system, porous cotton terry cloth was used as a fibrous matrix and the matrix was fixed on agitation shaft and inside baffles. Firstly, free-cell fermentations with batch and fed-batch modes were carried out under pH 6.0. The yield and butyric acid/acetic acid (B/A) ratio reached 0.387 g/g and 4.70 g/g in batch mode, and 0.426 g/g and 8.09 g/g in fed-batch mode, respectively. When implementing fed-batch fermentation with immobilized cells in IFBB, the concentration and productivity of butyric acid reached 45.38 g/L and 0.630 g/L/h, respectively, which were enhanced by 10 % in comparison with the free-cell fed-batch fermentation. Furthermore, a high yield of 0.440 g/g and B/A ratio of 12.75 g/g were also achieved in IFBB with fed-batch mode. Finally, the productivity of butyric acid could be further elevated to ∼0.90 g/L/h with repeated-batch in IFBB, while it was only 0.444 g/L/h in free-cell batch fermentation. These results obtained might show the potential for efficient butyric acid production in the IFBB system from renewable resources.

中文翻译：

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固定在内部纤维床生物反应器 (IFBB) 中的酪丁酸梭菌高效生产丁酸

摘要 固定化酪丁酸梭菌 ATCC 25755 在厌氧搅拌发酵罐中构建内纤维床生物反应器 (IFBB) 生产丁酸。和内部挡板。首先，在 pH 6.0 下进行分批和补料分批模式的游离细胞发酵。产量和丁酸/乙酸（B/A）比在分批模式下分别达到 0.387 g/g 和 4.70 g/g，在补料分批模式下分别达到 0.426 g/g 和 8.09 g/g。IFBB固定化细胞分批补料发酵，丁酸浓度和产率分别达到45.38 g/L和0.630 g/L/h，比游离细胞补料分批提高10%发酵。此外，在采用分批补料模式的 IFBB 中，也实现了 0.440 g/g 的高产量和 12.75 g/g 的 B/A 比。最后，在 IFBB 中重复批次可将丁酸的生产率进一步提高至 0.90 g/L/h，而在游离细胞批次发酵中仅为 0.444 g/L/h。获得的这些结果可能表明在 IFBB 系统中从可再生资源高效生产丁酸的潜力。