A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens Makino in Korea. Based on physiological and biochemical ch...
A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens Makino in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bacterial strain was identified as Pseudomonas aureofaciens. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antibiotic activity was found from the culture filtrate of M523 media and the active compounds were quantitatively bound to XAD adsorber resin. The antibiotic compound inhibited the growth of C. orbiculare at 1% on PDA but it had no activity to Pythium ultimum and Rhizoctonia solani which was reported to be sensitive to phenazine antibiotics. The chemical data from various chromatographic procedures showed that the active fraction consisted of phenazine derivatives and the active compounds was identified as phenazine 1-carboxylic acid.