Dataset Information

Co-production of acetoin and succinic acid by metabolically engineered Enterobacter cloacae.

ABSTRACT:

Background

Renewable chemicals have attracted attention due to increasing interest in environmental concerns and resource utilization. Biobased production of industrial compounds from nonfood biomass has become increasingly important as a sustainable replacement for traditional petroleum-based production processes depending on fossil resources. Therefore, we engineered an Enterobacter cloacae budC and ldhA double-deletion strain (namely, EC?budC?ldhA) to redirect carbon fluxes and optimized the culture conditions to co-produce succinic acid and acetoin.

Results

In this work, E. cloacae was metabolically engineered to enhance its combined succinic acid and acetoin production during fermentation. Strain EC?budC?ldhA was constructed by deleting 2,3-butanediol dehydrogenase (budC), which is involved in 2,3-butanediol production, and lactate dehydrogenase (ldhA), which is involved in lactic acid production, from the E. cloacae genome. After redirecting and fine-tuning the E. cloacae metabolic flux, succinic acid and acetoin production was enhanced, and the combined production titers of acetoin and succinic acid from glucose were 17.75 and 2.75 g L^-1, respectively. Moreover, to further improve acetoin and succinic acid production, glucose and NaHCO₃ modes and times of feeding were optimized during fermentation of the EC?budC?ldhA strain. The maximum titers of acetoin and succinic acid were 39.5 and 20.3 g L^-1 at 72 h, respectively.

Conclusions

The engineered strain EC?budC?ldhA is useful for the co-production of acetoin and succinic acid and for reducing microbial fermentation costs by combining processes into a single step.

SUBMITTER: Su HY

PROVIDER: S-EPMC7816431 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

Co-production of acetoin and succinic acid by metabolically engineered Enterobacter cloacae.

Su Hsiang-Yen HY Li Hua-Ying HY Xie Cai-Yun CY Fei Qiang Q Cheng Ke-Ke KK

Biotechnology for biofuels 20210119 1

<h4>Background</h4>Renewable chemicals have attracted attention due to increasing interest in environmental concerns and resource utilization. Biobased production of industrial compounds from nonfood biomass has become increasingly important as a sustainable replacement for traditional petroleum-based production processes depending on fossil resources. Therefore, we engineered an Enterobacter cloacae budC and ldhA double-deletion strain (namely, EC∆budC∆ldhA) to redirect carbon fluxes and optimi ...[more]

PMID: 33468210

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Project description:BackgroundThe microbial production of succinic acid (SA) from renewable carbon sources via the reverse TCA (rTCA) pathway is a process potentially accompanied by net-fixation of carbon dioxide (CO2). Among reduced carbon sources, glycerol is particularly attractive since it allows a nearly twofold higher CO2-fixation yield compared to sugars. Recently, we described an engineered Saccharomyces cerevisiae strain which allowed SA production in synthetic glycerol medium with a maximum yield of 0.23 Cmol Cmol-1. The results of that previous study suggested that the glyoxylate cycle considerably contributed to SA accumulation in the respective strain. The current study aimed at improving the flux into the rTCA pathway accompanied by a higher CO2-fixation and SA yield.ResultsBy changing the design of the expression cassettes for the rTCA pathway, overexpressing PYC2, and adding CaCO3 to the batch fermentations, an SA yield on glycerol of 0.63 Cmol Cmol-1 was achieved (i.e. 47.1% of the theoretical maximum). The modifications in this 2nd-generation SA producer improved the maximum biomass-specific glycerol consumption rate by a factor of nearly four compared to the isogenic baseline strain solely equipped with the dihydroxyacetone (DHA) pathway for glycerol catabolism. The data also suggest that the glyoxylate cycle did not contribute to the SA production in the new strain. Cultivation conditions which directly or indirectly increased the concentration of bicarbonate, led to an accumulation of malate in addition to the predominant product SA (ca. 0.1 Cmol Cmol-1 at the time point when SA yield was highest). Off-gas analysis in controlled bioreactors with CO2-enriched gas-phase indicated that CO2 was fixed during the SA production phase.ConclusionsThe data strongly suggest that a major part of dicarboxylic acids in our 2nd-generation SA-producer was formed via the rTCA pathway enabling a net fixation of CO2. The greatly increased capacity of the rTCA pathway obviously allowed successful competition with other pathways for the common precursor pyruvate. The overexpression of PYC2 and the increased availability of bicarbonate, the co-substrate for the PYC reaction, further strengthened this capacity. The achievements are encouraging to invest in future efforts establishing a process for SA production from (crude) glycerol and CO2.

Dataset Information

Co-production of acetoin and succinic acid by metabolically engineered Enterobacter cloacae.

Background

Results

Conclusions

Publications

Co-production of acetoin and succinic acid by metabolically engineered Enterobacter cloacae.

Similar Datasets

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