Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
Bioresour Technol. 2012 Aug;118:553-62. doi: 10.1016/j.biortech.2012.05.079. Epub 2012 May 24.
Propionic acid production from glycerol was studied using Propionibacterium acidipropionici DSM 4900 cells immobilized on polyethylenimine-treated Poraver (PEI-Poraver) and Luffa (PEI-Luffa), respectively. Using PEI-Luffa, the average productivity, yield and concentration of propionic acid from 40 g L(-1) glycerol were 0.29 g L(-1) h(-1), 0.74 mol(PA) mol(Gly)(-1) and 20 g L(-1), respectively, after four consecutive recycle-batches. PEI-Poraver supported attachment of 31 times higher amounts of cells than PEI-Luffa and produced 20, 28 and 35 g L(-1) propionic acid from 40, 65 and 85 g L(-1) glycerol, respectively (0.61 mol(PA) mol(Gly)(-1)). The corresponding production rates were 0.86, 0.43 and 0.35 g L(-1) h(-1), which are the highest reported from glycerol via batch or fed-batch fermentations for equivalent propionic acid concentrations. Using a continuous mode of operation at a dilution rate of 0.1 h(-1), cell washout was observed in the bioreactor with free cells; however, propionic acid productivity, yield and concentration were 1.40 g L(-1) h(-1), 0.86 mol(PA) mol(Gly)(-1), and 15 g L(-1), respectively, using immobilized cells in the PEI-Poraver bioreactor. The choice of the immobilization matrix can thus significantly influence the fermentation efficiency and profile. The bioreactor using cells immobilized on PEI-Poraver allowed the fermentation of higher glycerol concentrations and provided stable and higher fermentation rates than that using free cells or the cells immobilized on PEI-Luffa.
使用分别用聚乙烯亚胺处理过的 Porave（PEI-Porave）和丝瓜络（PEI-Luffa）固定化丙酸棒杆菌 DSM 4900 细胞，研究了从甘油生产丙酸。使用 PEI-Luffa，在连续四批循环后，从 40 g/L 甘油中获得的丙酸的平均生产力、产率和浓度分别为 0.29 g/L/h、0.74 mol(PA) mol(Gly)(-1)和 20 g/L。PEI-Porave 支持的细胞附着量比 PEI-Luffa 高 31 倍，分别从 40、65 和 85 g/L 甘油中产生 20、28 和 35 g/L 丙酸（0.61 mol(PA) mol(Gly)(-1)）。相应的生产速率分别为 0.86、0.43 和 0.35 g/L/h，这是在等效丙酸浓度下通过分批或补料分批发酵从甘油获得的最高报道值。在稀释率为 0.1 h(-1)的连续操作模式下，在无细胞的生物反应器中观察到细胞洗脱；然而，使用 PEI-Porave 生物反应器中的固定化细胞，丙酸生产力、产率和浓度分别为 1.40 g/L/h、0.86 mol(PA) mol(Gly)(-1)和 15 g/L。因此，固定化基质的选择会显著影响发酵效率和特征。使用固定化细胞的生物反应器能够发酵更高浓度的甘油，并提供比使用游离细胞或固定在 PEI-Luffa 上的细胞更稳定和更高的发酵速率。
