Efficient markerless gene deletions in Pseudomonas protegens Pf-5 using a upp-based counterselective system.

Objectives: Developing a counterselective system for efficient markerless gene deletions in biocontrol strain P. protegens Pf-5.

Results: We successfully implemented a markerless deletion of upp in Pf-5 to obtain the 5-FU resistant strain Pf5139.

ArgR directly inhibits lipA transcription in Pseudomonas protegens Pf-5.

ArgR, a transcriptional regulator belonging to the AraC/XylS family, plays a key role in arginine metabolism regulation. ArgR has also been found to repress the transcription of a lipase gene, but its molecular mechanism is still unknown. In this study, we investigated the molecular mechanism acting on the expression of intracellular lipase gene lipA regulated by ArgR in Pseudomonas protegens Pf-5 through knockout and overexpression of argR, detection of DNA-protein interaction in vivo, determining whole-cell lipase activities of various strains derived from Pf-5, and examining β-galactosidase activities of various lacZ fusions.