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Complete PHB mobilization in Escherichia coli enhances the stress tolerance: a potential biotechnological application.

Wang Q, Yu H, Xia Y, Kang Z, Qi Q - Microb. Cell Fact. (2009)

Bottom Line: Poly-beta-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions.Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria.The successful expression of PHB biosynthesis and PHB depolymerase genes in E. coli was confirmed by PHB production and 3-hydroxybutyrate secretion.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, School of Life Science, Shandong University, Jinan, 250100 PR China. qiqingsheng@sdu.edu.cn.

ABSTRACT

Background: Poly-beta-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions. Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria.

Results: The successful expression of PHB biosynthesis and PHB depolymerase genes in E. coli was confirmed by PHB production and 3-hydroxybutyrate secretion. Starvation experiment demonstrated that the complete PHB mobilization system in E. coli served as an intracellular energy and carbon storage system, which increased the survival rate of the host when carbon resources were limited. Stress tolerance experiment indicated that E. coli strains with PHB production and mobilization system exhibited an enhanced stress resistance capability.

Conclusion: This engineered E. coli with PHB mobilization has a potential biotechnological application as immobilized cell factories for biocatalysis and biotransformation.

No MeSH data available.


Related in: MedlinePlus

Effect of PHB mobilization on the survival of starved E. coli strains. (a) Relative survival rate. (Filled square) E. coli DH5α; (filled circle) E. coli DH5α (pSCP-CAB); (filled triangle) E. coli DH5α (pQWQ2/pSCP-CAB). (b) PHB consumption and 3HB secretion during starvation. (Filled circle) relative PHB content of E. coli DH5α (pSCP-CAB); (filled triangle) relative PHB content of E. coli DH5α (pQWQ2/pSCP-CAB); (filled pentacle) 3HB secretion of E. coli DH5α (pQWQ2/pSCP-CAB).
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Figure 3: Effect of PHB mobilization on the survival of starved E. coli strains. (a) Relative survival rate. (Filled square) E. coli DH5α; (filled circle) E. coli DH5α (pSCP-CAB); (filled triangle) E. coli DH5α (pQWQ2/pSCP-CAB). (b) PHB consumption and 3HB secretion during starvation. (Filled circle) relative PHB content of E. coli DH5α (pSCP-CAB); (filled triangle) relative PHB content of E. coli DH5α (pQWQ2/pSCP-CAB); (filled pentacle) 3HB secretion of E. coli DH5α (pQWQ2/pSCP-CAB).

Mentions: In order to confirm the complete PHB mobilization in engineered E. coli, all the strains were examined for long term starvation in M9 medium without carbon source (32 days). Fig 3A showed that the cell number of all strains began to reduce gradually from the third day of the starvation except the PHB mobilization strain E. coli DH5α (pQWQ2/pSCP-CAB), which exhibited an obvious multiplication during starvation. At the end of the starvation, the cell population of E. coli DH5α (pQWQ2/pSCP-CAB) increased by three-fold while the other strains without a PHB mobilization system had a under 1% of survival (Fig. 3A). Only about 4% of the cells survived when E. coli DH5α (pQWQ2/pSCP-CAB) was incubated in potassium phosphate buffer without nitrogen source or carbon source (Additional file 1, Fig. S2). This result proved the necessity of nitrogen for the survival and multiplication during the starvation. After being starved for 32 days, E. coli DH5α (pQWQ2/pSCP-CAB) consumed 72% of its intracellular PHB, indicating the re-utilization of PHB as carbon and energy source (Fig. 3B). During the starvation experiment, we found that the free 3HB of E. coli DH5α (pQWQ2/pSCP-CAB) in the medium was maintained at a low level of about 0.1-0.2 g/L. Calculation of the PHB degradation revealed that totally about 0.8 g/L 3HB was produced by depolymerization of PHB during the starvation. This indicated that E. coli DH5α (pQWQ2/pSCP-CAB) consumed 0.6 g/L 3HB for carbon and energy. This data further confirmed the existing of PHB cycle in E. coli DH5α (pQWQ2/pSCP-CAB).


Complete PHB mobilization in Escherichia coli enhances the stress tolerance: a potential biotechnological application.

Wang Q, Yu H, Xia Y, Kang Z, Qi Q - Microb. Cell Fact. (2009)

Effect of PHB mobilization on the survival of starved E. coli strains. (a) Relative survival rate. (Filled square) E. coli DH5α; (filled circle) E. coli DH5α (pSCP-CAB); (filled triangle) E. coli DH5α (pQWQ2/pSCP-CAB). (b) PHB consumption and 3HB secretion during starvation. (Filled circle) relative PHB content of E. coli DH5α (pSCP-CAB); (filled triangle) relative PHB content of E. coli DH5α (pQWQ2/pSCP-CAB); (filled pentacle) 3HB secretion of E. coli DH5α (pQWQ2/pSCP-CAB).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2746179&req=5

Figure 3: Effect of PHB mobilization on the survival of starved E. coli strains. (a) Relative survival rate. (Filled square) E. coli DH5α; (filled circle) E. coli DH5α (pSCP-CAB); (filled triangle) E. coli DH5α (pQWQ2/pSCP-CAB). (b) PHB consumption and 3HB secretion during starvation. (Filled circle) relative PHB content of E. coli DH5α (pSCP-CAB); (filled triangle) relative PHB content of E. coli DH5α (pQWQ2/pSCP-CAB); (filled pentacle) 3HB secretion of E. coli DH5α (pQWQ2/pSCP-CAB).
Mentions: In order to confirm the complete PHB mobilization in engineered E. coli, all the strains were examined for long term starvation in M9 medium without carbon source (32 days). Fig 3A showed that the cell number of all strains began to reduce gradually from the third day of the starvation except the PHB mobilization strain E. coli DH5α (pQWQ2/pSCP-CAB), which exhibited an obvious multiplication during starvation. At the end of the starvation, the cell population of E. coli DH5α (pQWQ2/pSCP-CAB) increased by three-fold while the other strains without a PHB mobilization system had a under 1% of survival (Fig. 3A). Only about 4% of the cells survived when E. coli DH5α (pQWQ2/pSCP-CAB) was incubated in potassium phosphate buffer without nitrogen source or carbon source (Additional file 1, Fig. S2). This result proved the necessity of nitrogen for the survival and multiplication during the starvation. After being starved for 32 days, E. coli DH5α (pQWQ2/pSCP-CAB) consumed 72% of its intracellular PHB, indicating the re-utilization of PHB as carbon and energy source (Fig. 3B). During the starvation experiment, we found that the free 3HB of E. coli DH5α (pQWQ2/pSCP-CAB) in the medium was maintained at a low level of about 0.1-0.2 g/L. Calculation of the PHB degradation revealed that totally about 0.8 g/L 3HB was produced by depolymerization of PHB during the starvation. This indicated that E. coli DH5α (pQWQ2/pSCP-CAB) consumed 0.6 g/L 3HB for carbon and energy. This data further confirmed the existing of PHB cycle in E. coli DH5α (pQWQ2/pSCP-CAB).

Bottom Line: Poly-beta-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions.Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria.The successful expression of PHB biosynthesis and PHB depolymerase genes in E. coli was confirmed by PHB production and 3-hydroxybutyrate secretion.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, School of Life Science, Shandong University, Jinan, 250100 PR China. qiqingsheng@sdu.edu.cn.

ABSTRACT

Background: Poly-beta-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions. Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria.

Results: The successful expression of PHB biosynthesis and PHB depolymerase genes in E. coli was confirmed by PHB production and 3-hydroxybutyrate secretion. Starvation experiment demonstrated that the complete PHB mobilization system in E. coli served as an intracellular energy and carbon storage system, which increased the survival rate of the host when carbon resources were limited. Stress tolerance experiment indicated that E. coli strains with PHB production and mobilization system exhibited an enhanced stress resistance capability.

Conclusion: This engineered E. coli with PHB mobilization has a potential biotechnological application as immobilized cell factories for biocatalysis and biotransformation.

No MeSH data available.


Related in: MedlinePlus