Authentication and characterization of a candidate antagonistic bacterium against soft rot of Amorphophallus konjac

Bacterial soft rot of Amorphophallus konjac is the most destructive disease caused by Pectobacterium spp. Until now effective control of this disease is unavailable. In the present study, attempts were made to find antagonistic bacteria to control the disease. After screening bacteria from infected konjac plants, a strain (21-2) was found to be able to effectively inhibit the pathogens of soft rot and it was identified as Serratia marcescens using a polyphasic approach including morphological characterization and analysis of the 16S rDNA gene sequence. In an HPLC MS analysis, the active substances of strain 21-2 were purified and separated from fermentation broth and divided into 36 constituents. The substances with a retention time of 17.35 min with the ultraviolet absorption peak wavelength at 211 nm and 261 nm and the molecular mass was 454 Da had the highest activity to inhibit the pathogens of soft rot on konjac. This constituent could be the potential biocontrol agent against the pathogens of soft rot on konjac. (C) 2011 Elsevier Ltd. All rights reserved.