Synergistic Antifungal Activity of Chitinolytic Enzymes and Prodigiosin Produced by Biocontrol Bacterium, Serratia marcescens Strain B2 against Gray Mold Pathogen, Botrytis cinerea

strain B2 is an effective biocontrol agent against gray mold of cyclamen, caused by Botrytis cinerea Persoon. Strain B2 has strong antifungal activity against B. cinerea in vitro. The culture filtrate was found to contain different types of chitinolytic enzyme activity, including endochitinase and chitobiase activity. Four chitinolytic enzymes were detected among the extracellular proteins of strain B2. Two major enzymes, a 58-kDa endochitinase and a 98-kDa chitobiase, were purified by chromatography and electrofocusing, respectively. Both enzymes inhibited spore germination of B. cinerea. And a red pigment, prodigiosin, extracted and purified from the bacterial cells, also inhibited spore germination. When prodigiosin and the chitinolytic enzymes were applied in concert, a synergistic inhibitory effect was observed. S. marcescens strain B2 has multiple modes of action against the pathogen.