Expression of a fused fpg gene in E. coli and engineering a strain Comamonas testosteroni ZD4-1-fpg for environmental application

Abstract

A fused fpg gene composed of phe B and gfp gene, which encoded catechol 2,3-dioxygenase (C23O) and green fluorescence protein (GFP), respectively, was expressed in E. coli to investigate its functional intactness. The expression results showed that C23O activity was detected in the induced bacterial cells and the E. coli cells containing the fusion protein emitted green fluorescence under epifluorescence microscopy, indicating that the fused fpg gene expressed correctly in E. coli. After expressed in E. coli, the fpg gene was transferred into the chromosome of a wild-type strain Comamonas testosteroni ZD4-1 by a pUT mini-Tn5 type vector pUT-Hg-fpg. The constructed genetically engineered bacterium strain C. testosteroni ZD4-1-fpg was also able to emit green fluorescence under epifluorescence microscopy. The stability assay showed that fpg gene could be detected in the host strain after 10 times of transfer inoculation, indicating the fpg gene is very stable. These results revealed that the Comamona testosteroni ZD4-1-fpg maybe used as not only an aromatic compound-biodegrading strain but also as an indicator strain to monitor the fate of the bacterial strains in the bioremediation.

Keywords:

• fpg gene
• catechol 2,3-dioxygenase (C23O)
• green fluorescence protein (GFP)
• transposon vector
• genetically engineered bacterium

Acknowledgments

This work was supported by the National Support Project for Science and Technology of China (2007BAC03A10) and the Project of National Natural Science Foundation of China (40675077). The authors would like to thank Dr. Billy Wolfe and the anonymous reviewers for their time and help.

Notes

∗ Can not be determined.