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[Objective] To address the bottlenecks of heavy reliance on fossil resources and severe environmental pollution associated with chemical synthesis, circumvent the “competing with humans for food” dilemma of conventional sugar-based biorefineries, and contribute to the achievement of carbon neutrality. This study developed a low-carbon engineering strain that can directly capture one-carbon (C1) gases and synthesize high-value-added products via metabolic engineering, thereby realizing the sustainable and efficient biosynthesis of ethyl acetate (EA). [Methods] With the autotrophic microorganism Clostridium ljungdahlii, which possesses a natural carbon-fixing ability, as the expression chassis, the lipase B from Candida antarctica (CALB) exhibiting robust esterification activity was heterologously expressed, and thus a metabolic pathway for converting intracellular short-chain precursors (acetate and ethanol) into EA was constructed. To overcome the challenges of low cell density and misallocated precursor pools inherent in autotrophic carbon fixation, we systematically parsed and reshaped different trophic regimes for fermentation. The performance of the recombinant strain was evaluated across heterotrophic (fructose), autotrophic (CO/CO2), and mixotrophic (fructose+CO/CO2) regimes in terms of biomass accumulation, metabolic flux distribution, and target product synthesis. [Results] The foreign lipase CALB was successfully and functionally expressed inside the acetogenic chassis, effectively driving the precursor flux toward target ester synthesis. The engineered strain produced 16.49 mg/L of EA under heterotrophic conditions and 9.18 mg/L of EA under purely autotrophic conditions. Crucially, the dual-substrate mixotrophic fermentation regime not only bypassed the carbon catabolite repression (CCR) effect but also synergistically enhanced both cell growth and precursor supply. This approach boosted the ultimate EA titer to 36.25 mg/L, demonstrating superior catalytic efficiency and targeted esterification performance compared with single trophic modes. [Conclusion] The C. ljungdahlii strain engineeredthrough systematic metabolic modifications and fermentation mode remodeling can successfully capture and convert greenhouse gases/industrial off-gases into high-value-added ester products. This gas-fermenting cell factory represents a promising chassis for the production of high-value-added derivatives in the future, expanding the technical frontiers for low-carbon industrial blueprints driven by synthetic biology.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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