Construction of Pseudomonas sp. GP72 rpeB mutant and its regulation on PCA and 2-OH-PHZ biosynthesis

Abstract:

[Objective] Rhizobacterium Pseudomonas chlororaphis GP72 produces two antibiotics, phenazine-1-carboxilic acid (PCA) and 2-hydroxyphenazine (2-OH-PHZ). RpeB is the response regulator (RR) of RpeA/RpeB two-component signal transduction system. We studied the effect of RpeB on PCA and 2-OH-PZH biosynthesis and its genes expression. [Methods] The rpeB gene was amplified from the GP72 genome. The rpeB mutant (GP72BN) was constructed through inserted inactivation of kanamycin resistance cassette and homologous recombination. Phenazines production assay, gene complement experiment and qRT-PCR analysis were used to assess the influence of RpeB on PCA and 2-OH-PHZ biosynthesis and its gene expression. [Results] In KMB media, PCA and 2-OH-PHZ production of rpeB mutant was decreased by 49.5% and 67.3%. The complementation of rpeB could recover the production of these two phenazine antibiotics. The results of qRT-PCR showed that the transcription of phzI/phzR and phzE strongly decreased in rpeB mutant, but the transcription of phzO only decreased a little. [Conclusion] RpeB positively regulates PCA and 2-OH-PHZ biosynthesis, and it might work for upstream of quorum sensing gene phzI/phzR to influence the expression of phz operon.