Outer Membrane Vesicles Mediated Horizontal Transfer of an Aerobic Denitrification Gene between Escherichia coli

Bacterial genetic material can be horizontally transferred between microorganisms via outer membrane vesicles (OMVs) released by bacteria. Up to now, the application of vesicle-mediated horizontal transfer of \"degrading genes\" in environmental remediation has not been reported. In this study, the nirS gene from an aerobic denitrification bacterium, Pseudomonas stutzeri, was enclosed in a pET28a plasmid, transformed into Escherichia coli (E. coli) DH5 and expressed in E. coli BL21. The E. coli DH5 released OMVs containing the recombination plasmid pET28a-nirS. Moreover, the amount of released OMVs-protein and DNA in OMVs increase as heavy metal concentrations and temperature increased. When compared with the free pET28a-nirS plasmids inability to transform, nirS in OMVs could be transferred into E. coli BL21 with the transformation frequency of 2.76x106 CFU/g when the dosage of OMVs was 200 {micro}g under natural conditions, and nirS could express successfully in recipient bacteria. Furthermore, the recipient bacteria that received OMVs could produce 18.16 U ml-1 activity of nitrite reductase. Vesicle-mediated HGT of aerobic denitrification genes provides a novel bioaugmentation technology of nitrogen removal.\n\nImportancePrevious studies have reported that bacterial genetic material can be horizontally transferred between microorganisms via outer membrane vesicles(OMVs) released by bacteria. However, the application of vesicle-mediated horizontal transfer of \"degrading genes\" in environmental remediation has not been reported. In this study, we found that OMVs could mediate horizontal transfer of pET28a-nirS plasmid between E. coli under natural condition. The transformation frequency reached to 2.76x106, which was higher than that of the free plasmid. Vesicle-mediated HGT of aerobic denitrification genes provides a novel bioaugmentation technology of nitrogen removal.