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Enhancement of 3-hydroxypropionic acid production from glycerol by using a metabolic toggle switch.

Tsuruno K, Honjo H, Hanai T - Microb. Cell Fact. (2015)

Bottom Line: The conditional repression of glpK and tpiA was not effective for 3-HP production under our experimental conditions.The measurement of intracellular metabolites showed the metabolic toggle switch successfully controlled the metabolic flux.This result indicates the metabolic toggle switch can be applied in various bio-production using diverse substrates.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Bioinformatics, Graduate School of Systems Life Sciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. ktsuruno@brs.kyushu-u.ac.jp.

ABSTRACT

Background: 3-hydroxypropionic acid (3-HP) is an important platform for the production of C3 chemicals, including acrylic acid, methyl acrylate, and acrylamide. Microbial production of 3-HP is mainly due to glycerol metabolism. In this study, in order to improve microbial 3-HP production, we applied a metabolic toggle switch for controlling the glycerol metabolism to redirect the excess metabolic flux of central metabolic pathway toward an exogenous 3-HP producing pathway in Escherichia coli.

Results: The metabolic toggle switch enables conditional repression of the expression of a target gene during the fermentation. We individually performed conditional repression of glpK, tpiA, and gapA, which are involved in glycerol metabolism. The conditional repression of glpK and tpiA was not effective for 3-HP production under our experimental conditions. However, gapA conditional repression contributed to improve 3-HP production (titer, 54.2 ± 1.5 mM; yield, 32.1 ± 1.3 %) compared with that for the wild type strain. Additional deletion of endogenous yqhD, which is responsible for the production of a major byproduct, 1,3-propandiol, further increased 3-HP production (titer, 67.3 ± 2.1 mM; yield, 51.5 ± 3.2 %). The titer and yield were 80 and 94 % higher than those of the wild type strain, respectively. The obtained 3-HP yield from glycerol is comparable with the highest yield ever reported for microbial 3-HP production using glycerol as a sole carbon source. The measurement of intracellular metabolites showed the metabolic toggle switch successfully controlled the metabolic flux.

Conclusion: The conditional repression of gapA by using the metabolic toggle switch combined with deletion of endogeneous yqhD increased 3-HP production approximately twofold from glycerol. This result indicates the metabolic toggle switch can be applied in various bio-production using diverse substrates.

No MeSH data available.


Related in: MedlinePlus

3-HP production by a gapA conditional repression strain with deleted yqhD (TA3130). a Growth curve (OD600). b Time course of glycerol consumption. c Time course of 3-HP production. d Time course of 1,3-PDO production. Error bars represent the standard deviation (n = 3)
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Fig7: 3-HP production by a gapA conditional repression strain with deleted yqhD (TA3130). a Growth curve (OD600). b Time course of glycerol consumption. c Time course of 3-HP production. d Time course of 1,3-PDO production. Error bars represent the standard deviation (n = 3)

Mentions: TA2821_9 h (gapA conditional repression strain) produced higher concentrations of 1,3-PDO (18.9 ± 3.1 mM) as a major byproduct (Fig. 6d), indicating that endogenous yqhD decreased the metabolic flux from 3-HPA to 3-HP in the TA2821. To elevate the 3-HP production and prevent 1,3-PDO production, TA3130, an endogenous yqhD deletion strain from TA2821, was constructed (Figs. 1, 2; Table 1). The growth and glycerol consumption of TA3130 were comparable those of wild type strain (TA2463) (Fig. 7a, b). As shown in Fig. 7c, TA3130_9 h produced 67.3 ± 2.1 mM of 3-HP with a yield of 51.5 ± 3.2 % at 48 h, which were about 80 and 94 % higher, respectively, than those of TA2463. The maximum theoretical yield of 3-HP from glycerol under aerobic condition was estimated as 97 % [23]. Thus, the 3-HP yield from glycerol obtained with TA3130 was 53.1 % of the theoretical yield and was comparable to that of our previous report in which the highest 3-HP yield from glycerol (54.1 %) ever reported was achieved using a dual synthetic pathway in flask scale batch fermentation [24].Fig. 7


Enhancement of 3-hydroxypropionic acid production from glycerol by using a metabolic toggle switch.

Tsuruno K, Honjo H, Hanai T - Microb. Cell Fact. (2015)

3-HP production by a gapA conditional repression strain with deleted yqhD (TA3130). a Growth curve (OD600). b Time course of glycerol consumption. c Time course of 3-HP production. d Time course of 1,3-PDO production. Error bars represent the standard deviation (n = 3)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4594890&req=5

Fig7: 3-HP production by a gapA conditional repression strain with deleted yqhD (TA3130). a Growth curve (OD600). b Time course of glycerol consumption. c Time course of 3-HP production. d Time course of 1,3-PDO production. Error bars represent the standard deviation (n = 3)
Mentions: TA2821_9 h (gapA conditional repression strain) produced higher concentrations of 1,3-PDO (18.9 ± 3.1 mM) as a major byproduct (Fig. 6d), indicating that endogenous yqhD decreased the metabolic flux from 3-HPA to 3-HP in the TA2821. To elevate the 3-HP production and prevent 1,3-PDO production, TA3130, an endogenous yqhD deletion strain from TA2821, was constructed (Figs. 1, 2; Table 1). The growth and glycerol consumption of TA3130 were comparable those of wild type strain (TA2463) (Fig. 7a, b). As shown in Fig. 7c, TA3130_9 h produced 67.3 ± 2.1 mM of 3-HP with a yield of 51.5 ± 3.2 % at 48 h, which were about 80 and 94 % higher, respectively, than those of TA2463. The maximum theoretical yield of 3-HP from glycerol under aerobic condition was estimated as 97 % [23]. Thus, the 3-HP yield from glycerol obtained with TA3130 was 53.1 % of the theoretical yield and was comparable to that of our previous report in which the highest 3-HP yield from glycerol (54.1 %) ever reported was achieved using a dual synthetic pathway in flask scale batch fermentation [24].Fig. 7

Bottom Line: The conditional repression of glpK and tpiA was not effective for 3-HP production under our experimental conditions.The measurement of intracellular metabolites showed the metabolic toggle switch successfully controlled the metabolic flux.This result indicates the metabolic toggle switch can be applied in various bio-production using diverse substrates.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Bioinformatics, Graduate School of Systems Life Sciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. ktsuruno@brs.kyushu-u.ac.jp.

ABSTRACT

Background: 3-hydroxypropionic acid (3-HP) is an important platform for the production of C3 chemicals, including acrylic acid, methyl acrylate, and acrylamide. Microbial production of 3-HP is mainly due to glycerol metabolism. In this study, in order to improve microbial 3-HP production, we applied a metabolic toggle switch for controlling the glycerol metabolism to redirect the excess metabolic flux of central metabolic pathway toward an exogenous 3-HP producing pathway in Escherichia coli.

Results: The metabolic toggle switch enables conditional repression of the expression of a target gene during the fermentation. We individually performed conditional repression of glpK, tpiA, and gapA, which are involved in glycerol metabolism. The conditional repression of glpK and tpiA was not effective for 3-HP production under our experimental conditions. However, gapA conditional repression contributed to improve 3-HP production (titer, 54.2 ± 1.5 mM; yield, 32.1 ± 1.3 %) compared with that for the wild type strain. Additional deletion of endogenous yqhD, which is responsible for the production of a major byproduct, 1,3-propandiol, further increased 3-HP production (titer, 67.3 ± 2.1 mM; yield, 51.5 ± 3.2 %). The titer and yield were 80 and 94 % higher than those of the wild type strain, respectively. The obtained 3-HP yield from glycerol is comparable with the highest yield ever reported for microbial 3-HP production using glycerol as a sole carbon source. The measurement of intracellular metabolites showed the metabolic toggle switch successfully controlled the metabolic flux.

Conclusion: The conditional repression of gapA by using the metabolic toggle switch combined with deletion of endogeneous yqhD increased 3-HP production approximately twofold from glycerol. This result indicates the metabolic toggle switch can be applied in various bio-production using diverse substrates.

No MeSH data available.


Related in: MedlinePlus