Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611.
Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611
Proc Natl Acad Sci U S A. 2018 Apr 24;115(17):4381-4386. doi: 10.1073/pnas.1801002115. Epub 2018 Apr 9.
Methane can be converted to triose dihydroxyacetone (DHA) by chemical processes with formaldehyde as an intermediate. Carbon dioxide, a by-product of various industries including ethanol/butanol biorefineries, can also be converted to formaldehyde and then to DHA. DHA, upon entry into a cell and phosphorylation to DHA-3-phosphate, enters the glycolytic pathway and can be fermented to any one of several products. However, DHA is inhibitory to microbes due to its chemical interaction with cellular components. Fermentation of DHA to d-lactate by strain TG113 was inefficient, and growth was inhibited by 30 g⋅L DHA. An ATP-dependent DHA kinase from (pDC117d) permitted growth of strain TG113 in a medium with 30 g⋅L DHA, and in a fed-batch fermentation the d-lactate titer of TG113(pDC117d) was 580 ± 21 mM at a yield of 0.92 g⋅g DHA fermented. strain LW225, with a higher glucose flux than , produced 811 ± 26 mM d-lactic acid at an average volumetric productivity of 2.0 g⋅L⋅h Fermentation of DHA required a balance between transport of the triose and utilization by the microorganism. Using other engineered strains, we also fermented DHA to succinic acid and ethanol, demonstrating the potential of converting CH and CO to value-added chemicals and fuels by a combination of chemical/biological processes.
甲烷可以通过以甲醛为中间产物的化学过程转化为三碳糖 1,3-二羟丙酮（DHA）。二氧化碳是包括乙醇/丁醇生物精炼厂在内的各种工业的副产品，也可以转化为甲醛，然后转化为 DHA。DHA 进入细胞后，磷酸化为 DHA-3-磷酸，进入糖酵解途径，可发酵成几种产物之一。然而，由于 DHA 与细胞成分的化学相互作用，它对微生物具有抑制作用。通过 菌株 TG113 将 DHA 发酵为 d-乳酸的效率不高，并且 30 g⋅L DHA 抑制生长。来自 的一种 ATP 依赖性 DHA 激酶（pDC117d）允许菌株 TG113 在含有 30 g⋅L DHA 的培养基中生长，在分批补料发酵中，TG113(pDC117d)的 d-乳酸产量为 580 ± 21 mM，产率为 0.92 g⋅g DHA 发酵。与 相比，葡萄糖通量更高的 菌株 LW225 生产了 811 ± 26 mM 的 d-乳酸，平均体积产率为 2.0 g⋅L⋅h DHA 的发酵需要平衡三碳糖的运输和微生物的利用。使用其他工程化的 菌株，我们还将 DHA 发酵为琥珀酸和乙醇，通过化学/生物过程的组合展示了将 CH 和 CO 转化为高附加值化学品和燃料的潜力。
