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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

Cell growth comparison of E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB). Growth was measured in LB medium with 20 g/L glucose without pH control.
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Figure 5: Cell growth comparison of E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB). Growth was measured in LB medium with 20 g/L glucose without pH control.

Mentions: Then, the engineered E. coli was used to investigate stress resistance capability. E. coli strain with PHB production or mobilization was confirmed to exhibit a changed stress capability (Fig. 4). When strains were incubated at 65°C in a water-bath, the PHB production strain, E. coli DH5α (pSCP-CAB), and PHB mobilization strain, E. coli DH5α (pQWQ2/pSCP-CAB), exhibited an increased heat resistance compared with the control strain (Fig. 4A). After 60 min of heating, about 30% and 7% of the initial number of cells remained alive, as compared to only 1.8% for the control strain. Likewise, E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB) showed an increased tolerance to UV irradiation compare to wild type E. coli (Fig. 4B). Acid resistance of the three strains was also studied: E. coli DH5α (pQWQ2/pSCP-CAB) exhibited a highest survival rate among the three strains (Fig. 4C). By 20 min of acid treatment, cell viability in E. coli DH5α (pQWQ2/pSCP-CAB), E. coli DH5α (pSCP-CAB) and E. coli DH5α control was reduced to 34.5%, 25.6% and 11.6% of the initial number of inoculated cells, respectively. By 40 min of acid treatment, cell viability was reduced to 9.4%, 3.2% and 1.8% of the initial number of inoculated cells, respectively. E. coli DH5α (pQWQ2/pSCP-CAB) also exhibited the highest survival rate when treated by a glucose-induced osmotic pressure (Fig. 4D). The viability of the E. coli DH5α control strain was especially affected by high concentration of glucose. Only about 2% of cells were alive when treated with 25% glucose. Interestingly, we found E. coli with PHB mobilization system exhibited a better growth compared with that with only PHB production system although E. coli DH5α (pQWQ2/pSCP-CAB) showed a long lag phase (Fig. 5).


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)

Cell growth comparison of E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB). Growth was measured in LB medium with 20 g/L glucose without pH control.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Cell growth comparison of E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB). Growth was measured in LB medium with 20 g/L glucose without pH control.
Mentions: Then, the engineered E. coli was used to investigate stress resistance capability. E. coli strain with PHB production or mobilization was confirmed to exhibit a changed stress capability (Fig. 4). When strains were incubated at 65°C in a water-bath, the PHB production strain, E. coli DH5α (pSCP-CAB), and PHB mobilization strain, E. coli DH5α (pQWQ2/pSCP-CAB), exhibited an increased heat resistance compared with the control strain (Fig. 4A). After 60 min of heating, about 30% and 7% of the initial number of cells remained alive, as compared to only 1.8% for the control strain. Likewise, E. coli DH5α (pSCP-CAB) and E. coli DH5α (pQWQ2/pSCP-CAB) showed an increased tolerance to UV irradiation compare to wild type E. coli (Fig. 4B). Acid resistance of the three strains was also studied: E. coli DH5α (pQWQ2/pSCP-CAB) exhibited a highest survival rate among the three strains (Fig. 4C). By 20 min of acid treatment, cell viability in E. coli DH5α (pQWQ2/pSCP-CAB), E. coli DH5α (pSCP-CAB) and E. coli DH5α control was reduced to 34.5%, 25.6% and 11.6% of the initial number of inoculated cells, respectively. By 40 min of acid treatment, cell viability was reduced to 9.4%, 3.2% and 1.8% of the initial number of inoculated cells, respectively. E. coli DH5α (pQWQ2/pSCP-CAB) also exhibited the highest survival rate when treated by a glucose-induced osmotic pressure (Fig. 4D). The viability of the E. coli DH5α control strain was especially affected by high concentration of glucose. Only about 2% of cells were alive when treated with 25% glucose. Interestingly, we found E. coli with PHB mobilization system exhibited a better growth compared with that with only PHB production system although E. coli DH5α (pQWQ2/pSCP-CAB) showed a long lag phase (Fig. 5).

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