Identification of a Novel Bioactive Phenazine Derivative and Regulation of phoP on Its Production in Streptomyces lomondensis S015

Natural phenazines are a class of multifunctional secondary metabolites of bacteria that play an important role in the biocontrol of plant pathogens. In this paper, a novel bioactive phenazine derivative was isolated from Streptomyces lomondensis S015 through silica gel chromatography and preparative high-performance liquid chromatography (HPLC). The structure was identified as 1-carboxyl-6-formyl-4,7,9-trihydroxy-phenazine (CFTHP) by NMR spectroscopy in combination with ultraperformance liquid chromatography & mass spectrometry (UPLC-MS). CFTHP could inhibit Pythium ultimum, Rhizoctonia solani, Septoria steviae, and Fusarium oxysporum f. sp. niveum with minimal inhibitory concentration (MIC) values of 16, 32, 16, and 16 μg/mL, respectively. A global regulatory gene phoP could positively regulate CFTHP biosynthesis since its production was 3.0-fold enhanced by phoP overexpression and inhibited by phoP deletion in Streptomyces lomondensis S015. These studies illustrated the potential of CFTHP as a promising biopesticide and provided a reference for phenazine production improvement.