Biodiversity and antimicrobial potential of bacterial endophytes from halophyte Salicornia brachiata

Extreme natural habitats like halophytes, marsh land, and marine environment are suitable arena for chemical ecology between plants and microbes having environmental impact. Endophytes are an ecofriendly option for the promotion of plant growth and to serve as sustainable resource of novel bioactive natural products. The present study, focusing on biodiversity of bacterial endophytes from Salicornia brachiata, led to isolation of around 336 bacterial endophytes. Phylogenetic analysis of 63 endophytes revealed 13 genera with 27 different species, belonging to 3 major groups: Firmicutes, Proteobacteria, and Actinobacteria. 30% endophytic isolates belonging to various genera demonstrated broad-spectrum antibacterial and antifungal activities against a panel of human, plant, and aquatic infectious agents. An endophytic isolate Bacillus amyloliquefaciens 5NPA-1, exhibited strong in-vitro antibacterial activity against human pathogen Staphylococcus aureus and phytopathogen Xanthomonas campestris. Investigation through LC-MS/MS-based molecular networking and bioactivity-guided purification led to the identification of three bioactive compounds belonging to lipopeptide class based on ¹H-, ¹³C-NMR and MS analysis. To our knowledge, this is the first report studying bacterial endophytic biodiversity of Salicornia brachiata and the isolation of bioactive compounds from its endophyte. Overall, the present study provides insights into the diversity of endophytes associated with the plants from the extreme environment as a rich source of metabolites with remarkable agricultural applications and therapeutic properties.