Notice of RetractionHigh Cell-Density Fermentation of Recombinant Escherichia coli Expressing PlyCB

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

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Lysins are murein hydrolases produced by bacteriophage which can kill bacteria efficiently and specifically. Streptococcus bacteriophage lysin PlyC, constituted by two peptides, PlyCA and PlyCB, can rapidly cleavage pathogenic β hemolytic streptococci in vitro. In order to achieve the objective of high cell-density fermentation and high level expression of the recombinant strain BL21(DE3)/ pET-32a(+)-PlyCB, the fed batch fermentation was carried out in a 5 liter automatic fermentor after flask shaking culture was done to obtain some optimized culture conditions. Results showed that after 12-14 h induction by controlling dissolved oxygen and by pH-stat feeding solution, high cell-density and high protein expression were achieved. Under the established conditions, 42.6 g/ L dry cell weight (DCW) could be obtained, and the expression rate of PlyCB reached 32% of total protein while the final cell density (OD₆₀₀) achieved 29.0. The study provides a basis for large scale production of this recombinant protein.