Expression of amplified synthetic ethanol pathway integrated usingTn7-tool and powered at the expense of eliminatedpta, ack, spo0A and spo0J during continuous syngas or CO2/H2 blend fermentation

    loading  Checking for direct PDF access through Ovid



To engineer acetogen biocatalyst selectively overproducing ethanol from synthesis gas or CO2/H2 as the only liquid carbonaceous product.

Methods and Results

Ethanol-resistant mutant originally capable of producing only acetate from CO2/CO was engineered to eliminate acetate production and spore formation using our proprietary Cre-lox66/lox71-system. Bi-functional aldehyde/alcohol dehydrogenase was inserted into the chromosome of the engineered mutant using Tn7-based approach. Recombinants with three or six copies of the inserted gene produced 525 mmol l−1 and 1018 mmol l−1 of ethanol, respectively, in five independent single-step fermentation runs 25 days each (P < 0·005) in five independent repeats using syngas blend 60% CO and 40% H2. Ethanol production was 64% if only CO2 + H2 blend was used compared with syngas blend (P < 0·005).


Elimination of genes unnecessary for syngas fermentation can boost artificial integrated pathway performance.

Significance and Impact of the Study

Cell energy released via elimination of phosphotransacetylase, acetate kinase and early-stage sporulation genes boosted ethanol production. Deletion of sporulation genes added theft-proof feature to the engineered biocatalyst. Production of ethanol from CO2/H2 blend might be utilized as a tool to mitigate global warming proportional to CO2 fermentation scale.

Related Topics

    loading  Loading Related Articles