Exploring the phytobeneficial and biocontrol capacities of endophytic bacteria isolated from hybrid vanilla pods

Abstract

Few studies have been conducted on endophytic bacteria of vanilla. In this study, 58 bacterial strains were isolated from two hybrid vanilla plants from Madagascar, Manitra ampotony and Tsy taitra. They were genetically characterised and divided into four distinct phylotypes. A selection of twelve strains corresponding to the identified genetic diversity were tested in vitro for four phytobeneficial capacities: phosphate solubilisation, free nitrogen fixation, phytohormone and siderophore production. They were also evaluated in vitro for their ability to biocontrol the growth of the vanilla pathogenic fungi, Fusarium oxysporum f. sp. radicis vanillae and Cholletotrichum orchidophilum. Bacteria belonging to three different phyla were found to be highly competent in each of the phytobeneficial capacities tested. Bacteria belonging to the phylum related to Bacillus siamensis showed the best capacity to inhibit fungal growth making them good candidates for controlling fungal diseases of vanilla. This competence was highlighted with spectral imaging showing the production of lipopeptides by the bacterial strains confronted with the pathogenic fungi of vanilla.