Characterization of Desertihabitans sp. FB5, a halophyte associated Actinomycetes producing phytohormones

Halophytes are remarkable plants that have evolved unique strategies to thrive in saline environments. Microbial communities of halophytes are being studied extensively as potential sources of bioactive compounds. Therefore, it is of interest to identify the secondary metabolites of the rhizospheric bacterial Desertihabitans sp. FB5 from the halophyte Salsola Imbricata. Strain Desertihabitans sp. FB5 was identified using a molecular technique (16S rDNA) and showed a similarity of 99% to Desertihabitans aurantiacus CPCC 204711T. Antifungal activity of the strain was tested against five different pathogenic fungi: Fusarium moniliforme, Altenaria mali, Magnaporthe grisea, Phytophthora capsici and Pythium ultimum in an in vitro assay. Desertihabitans sp. FB5 showed weak-to-moderate inhibition of different pathogenic fungi tested in the inhibitory assay. The production of lytic enzymes was evaluated using different enzymatic activities. Desertihabitans sp. FB5 was positive for both cellulolytic and lipolytic activities. To detect bioactive metabolites, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) were performed. Both analyses showed the presence of the antimicrobial compound bacitracin and phytohormones, Indole-3-acetic acid (IAA) and Gibberellin A3 (GA3) in the culture extracts of strain. Our results demonstrated that halophytes are recognised as key source of potent bacterial strains capable of producing metabolites of industrial and medical significance.