Antifungal Activity of Pseudomonas chlororaphis 1S4

The potential of Pseudomonas chlororaphis 1S4 strain as an antifungal biocontrol agent against three species of the economically important Fusarium pathogens: Fusarium proliferatum C1, Fusarium oxysporum F6, and Fusarium solani F7 is studied. P. chlororaphis 1S4 24 and 48 h fresh and sterilized broth cultures were used to assess their antifungal properties for 168 hours. P. chlororaphis 1S4 imposed fungal growth inhibition of 64-85% against all fungal species, best presented at a relatively early stage of the fungi development (72 h) and sustained throughout the whole cultivation period. The sterilized broth bacterial cultures maintained about 60% - 100% of the fresh culture potential to retard the fungal growth. P. chlor¬oraphis 1S4 ability to produce exocellular phenazine-1-carboxylic acid and siderophores was determined. Their antifungal effect was checked after a high-temperature treatment. The potent antifungal activity of the P. chlororaphis 1S4 strain is speculated to be related to the biosynthesis of these biologically active substances that serve as effective bio-fungicides. Thus, the P. chlororaphis 1S4 antifungal potential could be utilized in agricultural initiatives focused on biocontrol.