Identification of Antibiotic Red Pigments of Serratia marcescens F-1-1, a Biocontrol Agent of Damping-off of Cucumber, and Antimicrobial Activity against Other Plant Pathogens.

Abstract

The red pigmented strain F-1-1 of Serratia marcescens shows a strong antagonism against Phytophthora capsici, the pathogen of damping-off of cucumber seedlings, and its antagonistic activity is due to the production of antibiotic red pigments. In the present study, purification and identification of the red pigments produced by the strain F-1-1 were performed. The water-insoluble red pigments were extracted from cultures on agar plates with ethanol and then chloroform, and purified by silica gel column chromatography. An active substance was isolated using the antifungal activity assay and was identified as prodigiosin, a known compound based on the spectral data. Purified prodigiosin inhibited the germination of cystospores and the growth of the fungal hyphae of P. capsici. It also showed antimicrobial activity against some plant-pathogenic fungi including Cochliobolus miyabeanus, Pythium spinosum, P. ultimum and against plant pathogenic bacteria including, Clavibacter michiganensis subsp. michiganensis and Erwinia carotovora subsp. carotovora. These results suggest that S. marcescens F-1-1 could be used as a biocontrol agent against many plant diseases other than cucumber damping-off.