Abstract Propionibacterium freudenreichii has been successfully applied to industrial anaerobic production of vitamin B12. In the traditional fed-batch fermentation process, 5,6-dimethylbenzimidazole (DMB) is used as a precursor. However, DMB can inhibit the synthesis of vitamin B12 metabolic intermediates, which is not conducive to semi-continuous fermentation of P. freudenreichii. To improve the fermentation efficiency, vitamin B12 ex-situ biosynthesis was proposed and a membrane separation coupling fermentation technology was designed with adenosylcobinamide (Ado-cbi) as the indicator signal. The results showed that P. freudenreichii cells should be partly separated online at 84 h with 0.22-μm spiral membrane. The fourfold concentrated suspension was suitable for ex-situ biosynthesis of vitamin B12 with the addition of 3.60 mg L−1 DMB at 30 ℃ and pH 7.0. In the semi-continuous coupling fermentation process, vitamin B12 concentration reached 56.76 ± 3.86 mg L−1, an improvement of 161.6 %, while reutilizing fermentation wastewater and improving the anaerobic fermentation efficiency of P. freudenreichii.

中文翻译：

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费氏丙酸杆菌利用膜分离偶联技术高效异位生物合成维生素 B12

摘要 费氏丙酸杆菌已成功应用于维生素B12的工业厌氧生产。在传统的分批补料发酵过程中，5,6-二甲基苯并咪唑 (DMB) 用作前体。但DMB可抑制维生素B12代谢中间体的合成，不利于费氏青霉的半连续发酵。为提高发酵效率，提出了维生素B12异位生物合成方法，并设计了一种以腺苷氨（Ado-cbi）为指示信号的膜分离耦合发酵技术。结果表明，0.22-μm 螺旋膜应在 84 h 时在线分离 P. freudenreichii 细胞。四倍浓缩悬浮液适用于添加3的维生素B12的异位生物合成。60 mg L-1 DMB 在 30 ℃和 pH 7.0。在半连续耦合发酵过程中，维生素B12浓度达到56.76±3.86 mg L-1，提高了161.6%，同时重复利用了发酵废水，提高了P. freudenreichii的厌氧发酵效率。