School of Life Sciences and Biotechnology, Dalian University of Technology, Dalian 116024, China.
J Biotechnol. 2013 May 10;165(1):18-21. doi: 10.1016/j.jbiotec.2013.02.009. Epub 2013 Feb 28.
In this article, effect of zinc supplementation on acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum was studied. It was found that when 0.001 g/L ZnSO4·7H2O was supplemented into the medium, solventogenesis was initiated earlier, with 21.0 g/L ABE (12.6 g/L butanol, 6.7 g/L acetone and 1.7 g/L ethanol) produced with a fermentation time of 40 h, compared to 19.4 g/L ABE (11.7 g/L butanol, 6.4 g/L acetone and 1.3g/L ethanol) produced with a fermentation time of 64 h in the control without zinc supplementation, and correspondingly ABE and butanol productivities were increased to 0.53 and 0.32 g/L/h from 0.30 and 0.18 g/L/h, increases of 76.7% and 77.8%, respectively, but their yields were not compromised. The reason for this phenomenon was attributed to rapid acids re-assimilation for more efficient ABE production, which was in accordance with relatively high pH and ORP levels maintained during the fermentation process. The maximum cell density increased by 23.8%, indicating that zinc supplementation stimulated cell growth, and consequently facilitated glucose utilization. However, more zinc supplementation exhibited an inhibitory effect, indicating that zinc supplementation at very low levels such as 0.001 g/L ZnSO4·7H2O will be an economically competitive strategy for improving butanol production.
本文研究了锌补充对丙酮丁醇乙醇（ABE）发酵的影响。结果表明，当向培养基中添加 0.001 g/L 的 ZnSO4·7H2O 时，溶剂生成更早开始，40 h 发酵即可生产 21.0 g/L ABE（12.6 g/L 丁醇、6.7 g/L 丙酮和 1.7 g/L 乙醇），而在没有锌补充的对照中，64 h 发酵仅可生产 19.4 g/L ABE（11.7 g/L 丁醇、6.4 g/L 丙酮和 1.3 g/L 乙醇），相应地 ABE 和丁醇的比生产率从 0.30 和 0.18 g/L/h 提高到 0.53 和 0.32 g/L/h，分别提高了 76.7%和 77.8%，但产率没有降低。这种现象的原因归因于快速的酸再同化，以实现更有效的 ABE 生产，这与发酵过程中保持的相对较高的 pH 值和氧化还原电位（ORP）水平一致。最大细胞密度增加了 23.8%，表明锌补充刺激了细胞生长，从而促进了葡萄糖的利用。然而，更多的锌补充表现出抑制作用，表明在非常低的水平（如 0.001 g/L ZnSO4·7H2O）添加锌将是一种经济上有竞争力的提高丁醇产量的策略。
