Isolation and screening of rhizobacteria as biocontrol agents against Fusarium oxysporum f.sp vanillae

Abstract

One of the major diseases that can reduce vanilla growth and production is stem rot caused by Fusarium oxysporum f.sp. vanillae. The objective of this study is to evaluate the rhizobacteria as biocontrol agents against Fusarium oxysporum f.sp vanillae. This research consists of isolation of rhizobacteria, antagonism assays, and identification of the rhizobacteria. A total of 263 isolates were evaluated in antagonism assays. There were 250 isolates isolated from vanilla, and 13 isolates were the collection of Plant Protection Laboratory, Indonesian Spice and Medicinal Crops Research Institute. The results showed that seven rhizobacteria isolates, i.e., L34, PS4, V116, KB7, KB10, M117a, and V112, could inhibit the mycelium growth by more than 60%. Rhizobacteria isolate L35, PS4, and V112 showed the highest inhibition, i.e., 64.92%, 72.72%, 68.72%, respectively. Based on the 16S rRNA sequence, isolate L35, PS4, and V112 were identified as Burkholderia vietnamiensis, B. ambifaria, and B lata, respectively. Further studies are needed to investigate the interaction between rhizobacteria and the host plants and formulate products to evaluate their effectiveness in the fields.