Department of Bio Environmental Chemistry and Institute of Life Science and Natural Resources, Wonkwang University, Iksan 570-749, Republic of Korea.
Bioprocess Biosyst Eng. 2013 May;36(5):591-5. doi: 10.1007/s00449-012-0815-0. Epub 2012 Sep 1.
Conversion of synthesis gas (CO and H2) to ethanol can be an alternative, promising technology to produce biofuels from renewable biomass. To distinguish microbial utilization of carbon source between fructose and synthesis gas CO and to evaluate biological production of ethanol from CO, we adopted the (13)C-enrichment of the CO substrate and hypothesized that the residual increase in δ(13)C of the cell biomass would reflect the increased contribution of (13)C-enriched CO. Addition of synthesis gas to live culture medium for ethanol fermentation by Clostridum ljungdahlii increased the microbial growth and ethanol production. Despite the high (13)C-enrichment in CO (99 atom % (13)C), however, microbial δ(13)C increased relatively small compared to the microbial growth. The uptake efficiency of CO estimated using the isotope mass balance equation was also very low: 0.0014 % for the low CO and 0.0016 % for the high CO treatment. Furthermore, the fast production of ethanol in the early stage indicated that the presence of sugar in fermentation medium would limit the utilization of CO as a carbon source by C. ljungdahlii.
将合成气（CO 和 H2）转化为乙醇可以是一种替代方法，有望从可再生生物质生产生物燃料。为了区分果糖和合成气 CO 之间微生物对碳源的利用，并评估 CO 生物生产乙醇，我们采用了（13）C 标记的 CO 底物，并假设细胞生物质中（13）C 富集的剩余增加将反映出（13）C 富集 CO 的增加贡献。添加合成气到 Clostridium ljungdahlii 的活培养基中进行乙醇发酵会增加微生物的生长和乙醇的生产。然而，尽管 CO 的（13）C 丰度很高（99 原子%（13）C），但与微生物的生长相比，微生物的（13）C 增加相对较小。使用同位素质量平衡方程估计的 CO 吸收效率也非常低：低 CO 处理为 0.0014%，高 CO 处理为 0.0016%。此外，在早期快速生产乙醇表明，发酵培养基中糖的存在会限制 C. ljungdahlii 将 CO 用作碳源的利用。
