Division of Biotechnology, Department of Chemistry, Center for Chemistry & Chemical Engineering, Lund University, 124, 221 00, Lund, Sweden.
Área de Biotecnología, Instituto de Investigaciones Fármaco Bioquímicas, Facultad de Ciencias Farmacéuticas y Bioquímicas, Universidad Mayor de San Andrés, 3239, La Paz, Bolivia.
Microb Cell Fact. 2023 Mar 4;22(1):43. doi: 10.1186/s12934-023-02049-7.
Microbial production of propionic acid (PA) from renewable resources is limited by the slow growth of the producer bacteria and product-mediated inhibition. The present study evaluates high cell density continuous PA fermentation from glycerol (Gly) using Acidipropionibacterium acidipropionici DSM 4900 in a membrane-based cell recycling system. A ceramic tubular membrane filter of 0.22 μm pore size was used as the filtering device for cell recycling. The continuous fermentations were run sequentially at dilution rates of 0.05 and 0.025 1/h using varying glycerol concentrations and two different yeast extract concentrations.
PA volumetric productivity of 0.98 g/L.h with a product yield of 0.38 g/g was obtained with 51.40 g/L glycerol at a yeast extract concentration of 10 g/L. Increasing the glycerol and yeast extract concentrations to 64.50 g/L and 20 g/L, respectively, increased in PA productivity, product yield, and concentration to 1.82 g/L.h, 0.79 g/g, and 38.37 g/L, respectively. However, lowering the dilution rate to 0.025 1/h reduced the production efficiency. The cell density increased from 5.80 to 91.83 g/L throughout the operation, which lasted for a period of 5 months. A tolerant variant of A. acidipropoinici exhibiting growth at a PA concentration of 20 g/L was isolated at the end of the experiment.
Applying the current approach for PA fermentation can overcome several limitations for process industrialization.
微生物利用可再生资源生产丙酸（PA）受到生产菌生长缓慢和产物抑制的限制。本研究使用丙酸短杆菌 DSM 4900 在基于膜的细胞回收系统中评估了从甘油（Gly）进行高细胞密度连续丙酸发酵。使用 0.22 μm 孔径的陶瓷管状膜过滤器作为细胞回收的过滤装置。连续发酵分别在稀释率为 0.05 和 0.025 1/h 的条件下进行，使用不同的甘油浓度和两种不同的酵母提取物浓度。
在酵母提取物浓度为 10 g/L 时，用 51.40 g/L 的甘油获得了 0.98 g/L.h 的 PA 容积产率，产物得率为 0.38 g/g。将甘油和酵母提取物浓度分别提高到 64.50 g/L 和 20 g/L，PA 生产率、产物得率和浓度分别提高到 1.82 g/L.h、0.79 g/g 和 38.37 g/L。然而，将稀释率降低到 0.025 1/h 会降低生产效率。细胞密度从 5.80 增加到 91.83 g/L，整个操作持续了 5 个月。在实验结束时，分离到了一种能够在 20 g/L PA 浓度下生长的耐酸短杆菌突变株。
应用当前的 PA 发酵方法可以克服工业化过程的一些限制。
