Construction of Pseudomonas sp. M18 psrA mutant and its regulation on PCA and Plt biosynthesis

Abstract:

[Objective] The rhizobacterium Pseudomonas sp. M18 can produce two antibiotics, phenazine-1-carboxylic acid (PCA) and pyoluteorin (Plt). PsrA belongs to the TetR family bacterial transcription regulator. To investigate the effect of PsrA on the PCA and Plt biosynthesis, the psrA gene was amplified from M18 strain genome. [Methods] The psrA mutant (M18psrA) was constructed through gene replacement of psrA by gentamicin resistance cassette and homologous recombination. Gene complement experiment and lacZ gene fusion report analysis further identified whether PsrA regulates the expression of antibiotics biosynthesis gene clusters. [Results] PCA and Plt production was respectively assayed in PPM and KMB media. PCA production of psrA mutant was significantly lower than that of its parent strain M18. However, Plt production of M18psrA was obviously increased 10?15 times as much as that of M18 strain. Gene complement experiment and lacZ gene fusion report analysis further confirmed that PsrA strongly up-regulated PCA biosynthesis and down-regulated Plt biosynthesis. [Conclusion] PsrA regulates distinctively on the PCA and Plt biosynthesis.