Production of polyhydroxyalkanoate from acetate by metabolically engineered Aeromonas hydrophilia

doi:10.1016/j.jbiosc.2020.05.003

Journal of Bioscience and Bioengineering

Volume 130, Issue 3, September 2020, Pages 290-294

https://doi.org/10.1016/j.jbiosc.2020.05.003 Get rights and content

Aeromonas hydrophila 4AK4 normally produces the copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBHHx) using lauric acid as the carbon source. In this study we reported the metabolic engineering of A. hydrophila 4AK4 for the production of polyhydroxyalkanoate (PHA) using acetate as a main carbon source. Recombinant A. hydrophila overexpressing β-ketothiolase and acetoacetyl-CoA reductase could accumulate poly-3-hydroxybutyrate (PHB) from acetate with a polymer content of 1.39 wt%. Further overexpression of acetate kinase/phosphotransacetylase and acetyl-CoA synthetase improved PHB content to 8.75 wt% and 19.82 wt%, respectively. When acetate and propionate were simultaneously supplied as carbon sources, the engineered A. hydrophila overexpressing β-ketothiolase, acetoacetyl-CoA reductase, and acetyl-CoA synthetase was found able to produce the copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV). The recombinant grew to 3.79 g/L cell dry weight (CDW) containing 15.02 wt% PHBV. Our proposed metabolic engineering strategies illustrate the feasibility for producing PHA from acetate by A. hydrophila.

Section snippets

Bacterial strains and culture medium

E. coli JM109 was employed as the host for plasmid construction and cultivated in Luria–Bertani (LB) medium at 37°C and 200 rpm. LB medium contained 5 g/L yeast extract, 10 g/L Bacto tryptone, and 10 g/L NaCl. A. hydrophila 4AK4 was grown on LB agar or in LB broth at 30°C. The conjugation of A. hydrophila 4AK4 and E. coli S17-1 was carried out via a mating process conducted in LB broth at 30°C for 4 h. When required, media were supplemented with 100 μg/mL ampicillin and/or 50 μg/mL kanamycin.

Plasmid construction

Acetate metabolism in A. hydrophila 4AK4

Recently, the feasibility of converting acetate to value-added chemicals and materials has been demonstrated in recombinant E. coli and Y. lipolytica (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16). These studies indicated that acetate could be a cost-effective feedstock for microbial fermentation. When acetate is employed as the carbon source, it is firstly transported into the cell and converted to acetyl-CoA under the catalyzation of acetate kinase/phosphotransacetylase (Ack-Pta pathway) or

Acknowledgments

This research was supported by the National Key Research and Development Program of China (Grant No. 2018YFA0900200), the National Natural Science Foundation of China (Grant No. 31870075), and the Fundamental Research Funds for the Central Universities (Grant No. XK1802-8, PT1904). The authors declare that they have no competing interests.

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Citation Excerpt :
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^‡: The first two authors contributed equally to this work.

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Production of polyhydroxyalkanoate from acetate by metabolically engineered Aeromonas hydrophilia

Section snippets

Bacterial strains and culture medium

Plasmid construction

Acetate metabolism in A. hydrophila 4AK4

Acknowledgments

Appl. Catal. A Gen.

Bioresour. Technol.

Biochem. Eng. J.

J. Biotechnol.

Microb. Cell Fact.

Synth. Syst. Biotechnol.

Bioresour. Technol.

Bioresour. Technol.

Process Biochem.

Bioresour. Technol.

Metab. Eng.

Gene

Metab. Eng.

Autotrophy at the thermodynamic limit of life: a model for energy conservation in acetogenic bacteria

Nat. Rev. Microbiol.