Abstract
An antifungal compound-producing bacterium was isolated and identified as a strain of Pseudomonas fluorescens K-188. P. fluorescens K-188 grown aerobically in a shrimp and crab shell powder medium produced antifungal compounds that in tests effectively inhibited several fungal phytopathogens including Fusarium solani, Trichoderma harzianum, and Pythium ultimum. Maximum inhibitory activity was obtained when P. fluorescens K-188 was grown aerobically at 37°C for 4 days in a medium consisting 1% shrimp and crab shell powder, 0.1% K2HPO4 and 0.05% MgSO4·7H2O at a pH of 7. The antifungal compounds obtained from ethanol precipitation of the culture supernatant of P. fluorescens K-188 retained more than 70% of its inhibitory activities to F. oxysporum even after being treated at 100°C for 10 min. Spore germination and germ spore elongation of F. oxysporum were inhibited by the antifungal compounds. In addition to antifungal activity. These characteristics were unique in comparison with those of other already-known Pseudomonas fluorescens.
