Construction of Pseudomonas sp. M18 pqsA mutant and its regulation on the plt operon

Abstract:

[Objective] The rhizobacterium P. aeruginosa M18 can produce two antibiotics, pyoluteorin (Plt) and phenazine-1-carboxilic acid (PCA). The PqsR/PQS quorum sensing system consists of the response regulatory protein PqsR and the signaling molecule PQS. Previous studies have shown that the pqsR gene negatively controls Plt biosynthesis and its gene expression. This study aims to investigate the effect of PQS on Plt biosynthesis and its gene expression. [Methods] The pqsA gene was amplified from the M18 genome. A chromosomal pqsA inactivated mutant strain of M18 was constructed by the homologous recombination technique. Plt production assay and lacZ reporter analysis were utilized to assess the influence of PQS on Plt biosynthesis and its gene expression. [Results] In KMB media, Plt production of pqsA mutant was partially increased 1.53 times as much as that of M18 strain. The addition of PQS caused a certain degree of down-regulation of plt expression. [Conclusion] PQS partially down-regulates Plt biosynthesis and its gene expression in M18.

Key words:Pseudomonas sp. M18, pqsA, Pyoluteorin, PQS