Novel in vitro methods for simultaneous screening of two antagonistic bacteria against multiple fungal phytopathogens in a single agar plate.

Two novel and rapid in vitro agar plate methods for simultaneous screening of two bacterial isolates for antagonism against multiple fungal phytopathogens in a single agar plate are described. In the modified plus streak method (MPS), in a 10 cm diameter PDA agar plate, two different bacterial isolates were screened against four fungal pathogens. The second method used 20 cm diameter PDA agar plate surface and was termed as the parallel multiple streak (PMS) method. Here, two bacterial isolates were screened for antagonism against ten fungal phytopathogens on a single agar plate surface. Our new methods are rapid and more economical, and could reduce the number of agar plates and the medium required for in vitro screening by several fold, compared to that used in the conventional dual culture plate assay. © King Abdulaziz City for Science and Technology 2022.