Isolation and identification of rhizobacteria having inhibitory capability on pathogenic fungi, Pythium SP.

Abstract

ABSTRACT            Hydroponics systems offer an advantage in reducing exposure to soil-borne pathogen; however, root diseases caused by endogenous microorganism especially pathogenic fungi can still occur and make undesirable results. The aim of this study was to isolate and identify rhizobacteria found in hydroponic lettuces, which had inhibitory capability to plant pathogenic fungi, Pythium sp. The results showed that a dominant group of rhizobacteria isolated from both infected roots and normal appearance lettuce roots was in the genera Serratia. All isolates of rhizobacteria showed inhibitory capability against Pythium sp., especially the Acinetobacter baumannii, which showed the highest inhibitory capability among all isolates. The lowest inhibitory capability among all of the isolated strain of rhizobacteria was Serratia entomophila strain M6. However, this inhibitory ability of rhizobacteria was observed only in the laboratory conditions. Thus, its inhibitory property should be re-tested before the application to real hydroponics farm conditions in order to reduce the infection of pathogenic fungi, which might cause the harmful effects against the vegetable that were grown in the hydroponics system.