Pseudomonas fluorescens K-188 produced antifungal materials that inhibited fungal phytopathogens Fusarium oxysporum, Fusarium solani, Trichoderma harzianum, and Pythium ultimum. In the concentration of antifungal materials, ethanol precipitation was better than ammonium sulfate precipitation. The antifungal materials retained almost 70% of the original antifungal activity even after being heated at 100degreesC for 10 min. Microscopic examination showed, when the antifungal materials were added, the hyphae of F oxysporum became thinner and the germination of the spores was inhibited. The antifungal activity of P fluorescens K-188 primarily should be correlated with cells themselves and an antifungal protein with molecular weight of 11 kDa. (C) 2004 Elsevier Inc. All rights reserved.