Wang Zhongqiang, Jin Ying, Yang Shang-Tian
William G. Lowrie Department of Chemical & Biomolecular Engineering, The Ohio State University, 140W. 19th Ave, Columbus, OH, 43210.
Biotechnol Bioeng. 2015 Mar;112(3):502-11. doi: 10.1002/bit.25466. Epub 2014 Oct 21.
Propionic acid is an important chemical with wide applications and its production via fermentation is of great interest. However, economic production of bio-based propionic acid requires high product titer, yield, and productivity in the fermentation. A highly efficient and stable high cell density (HCD) fermentation process with cell recycle by centrifugation was developed for propionic acid production from glucose using an acid-tolerant strain of Propionibacterium acidipropionici, which had a higher specific growth rate, productivity, and acid tolerance compared to the wild type ATCC 4875. The sequential batch HCD fermentation at pH 6.5 produced propionic acid at a high titer of ∼40 g/L and productivity of 2.98 g/L h, with a yield of ∼0.44 g/g. The product yield increased to 0.53-0.62 g/g at a lower pH of 5.0-5.5, which, however, decreased the productivity to 1.28 g/L h. A higher final propionic acid titer of >55 g/L with a productivity of 2.23 g/L h was obtained in fed-batch HCD fermentation at pH 6.5. A 3-stage simulated fed-batch process in serum bottles produced 49.2 g/L propionic acid with a yield of 0.53 g/g and productivity of 0.66 g/L h. These productivities, yields and propionic acid titers were among the highest ever obtained in free-cell propionic acid fermentation.
丙酸是一种具有广泛应用的重要化学品，通过发酵生产丙酸备受关注。然而，基于生物的丙酸经济生产要求发酵过程具有高产物滴度、产率和生产率。利用耐酸丙酸丙酸杆菌菌株，开发了一种通过离心进行细胞循环的高效稳定的高细胞密度（HCD）发酵工艺，用于从葡萄糖生产丙酸。与野生型ATCC 4875相比，该菌株具有更高的比生长速率、生产率和耐酸性。在pH 6.5下进行的连续批次HCD发酵产生的丙酸滴度高达约40 g/L，生产率为2.98 g/L·h，产率约为0.44 g/g。在较低的pH 5.0 - 5.5下，产物产率提高到0.53 - 0.62 g/g，但生产率降至1.28 g/L·h。在pH 6.5下的补料分批HCD发酵中，获得了更高的最终丙酸滴度>55 g/L，生产率为2.23 g/L·h。在血清瓶中进行的三阶段模拟补料分批工艺产生了49.2 g/L的丙酸，产率为0.53 g/g，生产率为0.66 g/L·h。这些生产率、产率和丙酸滴度是自由细胞丙酸发酵中获得的最高水平之一。
