Endophytic bacteria from root nodules of Ormosia macrocalyx with potential as plant growth promoters and antifungal activity

Aim: The present study was carried out to determine the diversity of cultivable endophytic bacteria associated to leguminous Ormosia macrocalix, and selected strains with potential as plant growth promoting bacteria (PGPB) and antifungal activity. Methodology: The isolated microorganisms were characterized using morphological, physiological and biochemical tests. The genetic diversity and phylogeny of isolated microorganisms were revealed by ERIC-PCR and sequencing of 16S rDNA. The plant growth promoting ability, plant inoculation assays and test for antagonism were evaluated to know the potential as plant growth-promoting bacteria. Results : The amount of 105 endophytic bacteria was extracted from the root nodules of legume. According to the phenotypic characteristics and phylogenetic analysis based on 16S rDNA sequences, these strains were grouped within the bacterial genera Bacillus, Citrobacter, Enterobacter, Novosphingobium, Paenibacillus, Pantoea and Ensifer. Due to the capacity for nitrogen fixation, auxin production, phosphate solubilization and antagonism against certain pathogenic fungi were confirmed to be done by the plant growth promoting bacteria. The isolate of Pantoea sp. CA-02 produced the highest concentrations of IAA and Ensifer sp. CA-14 showed the maximum nitrogen fixation potency. The Bacillus sp. CA-11 and Pantoea sp. CA-02 isolates exhibited higher degree of phosphate solubilization. Isolate CA-02 showed ability to inhibit the pathogenic fungi Fusarium oxyporum and F. solani. The fungus Fusarium verticilloides was strongly inhibited by isolate of Citrobacter sp. CA-15. Interpretation: Bacterial endophytes have potential use as bio-inoculants for the cultivation and propagation of leguminous tree O. macrocalyx. Use of endophytes may be particularly important in growing plants with high biological potential for reintroduction into their natural habitat.