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Background  Phenazine-1-carboxamide (PCN), a phenazine derivative, is strongly antagonistic to fungal phytopathogens. The high PCN biocontrol activity fascinated researcher’s attention in isolating and identifying novel bacterial strains combined with engineering strategies to target PCN as a lead molecule. The chemical route for phenazines biosynthesis employs toxic chemicals and display low productivities, require harsh reaction conditions, and generate toxic by-products. Phenazine biosynthesis using some natural phenazine-producers represent remarkable advantages of non-toxicity and possibly high yield in environmentally-friendlier settings.    Results  A biocontrol bacterium with antagonistic activity towards fungal plant pathogens, designated as strain HT66, was isolated from the rice rhizosphere. The strain HT66 was identified as  Pseudomonas chlororaphis  based on the colony morphology, gas chromatography of cellular fatty acids and 16S rDNA sequence analysis. The secondary metabolite produced by HT66 strain was purified and identified as PCN through mass spectrometry, and  1 H,  13 C nuclear magnetic resonance spectrum. The yield of PCN by wild-type strain HT66 was 424.87 mg/L at 24 h. The inactivation of  psrA  and  rpeA  increased PCN production by 1.66- and 3.06-fold, respectively, which suggests that  psrA  and  rpeA  are PCN biosynthesis repressors.  q RT-PCR analysis showed that the expression of  phzI ,  phzR , and  phzE  was markedly increased in the  psrA  and  rpeA  double mutant than in  psrA  or  rpeA  mutant. However, the transcription level of  rpeA  and  rpeB  in strain HT66Δ psrA  increased by 3.52- and 11.58-folds, respectively. The reduced  psrA  expression in HT66Δ rpeA  strain evidenced a complex regulation mechanism for PCN production in HT66.    Conclusion  In conclusion, the results evidence that  P. chlororaphis  HT66 could be modified as a potential cell factory for industrial-scale biosynthesis of PCN and other phenazine derivatives by metabolic engineering strategies.    Electronic supplementary material  The online version of this article (10.1186/s12934-018-0962-3) contains supplementary material, which is available to authorized users.

Enhanced biosynthesis of phenazine-1-carboxamide by engineered Pseudomonas chlororaphis HT66