The use of CO₂ as a building block for the synthesis of bulk chemicals appears highly attractive but has not been realized in industrial biotechnology due to the complexity and costly energy balance of conventional anabolic biosynthesis. Here, we describe the biocatalytic preparation of l-methionine from the abundant industrial intermediate methional under direct incorporation of CO₂ by reversing the catabolic Ehrlich pathway. Despite unfavourable chemical equilibrium (1/554 M⁻¹), the decarboxylase KdcA revealed half-maximal activity for its reverse reaction at astonishingly low CO₂ pressure (320 kPa). Accordingly, it was possible to synthesize l-methionine under a 2 bar CO₂ atmosphere when coupled to an energetically favourable transaminase or amino acid dehydrogenase reaction. Similarly, l-leucine and l-isoleucine were prepared via biocatalytic carboxylation of 3- or 2-methylbutanal, respectively. Our findings open a biotechnological route towards industrial products and enable further syntheses involving the fixation of gaseous CO₂ by simply applying decarboxylases in the reverse mode.

将CO ₂用作合成大量化学物质的基础材料似乎很有吸引力，但由于常规合成代谢生物合成的复杂性和昂贵的能量平衡，在工业生物技术中尚未实现。这里，我们描述的生物催化制备升-甲硫氨酸从下CO的直接掺入丰富工业中间甲硫₂通过反转分解代谢埃利希通路。尽管化学平衡不利（1/554 M ^-1），但脱羧酶KdcA在令人惊讶的低CO ₂压力（320 kPa）下仍显示出其逆反应的最大活性。因此，可以在2巴CO下合成1-甲硫氨酸。当与能量上有利的转氨酶或氨基酸脱氢酶反应偶联时，则为_2个大气压。类似地，分别通过3-或2-甲基丁醛的生物催化羧化来制备1-亮氨酸和1-异亮氨酸。我们的发现打开了一条向工业产品发展的生物技术路线，并且通过简单地以反向模式施加脱羧酶，就可以进行涉及固定气态CO ₂的进一步合成。