Imprints of PGPB association on the metabolic dynamism of Piper nigrum

ABSTRACT Endophytes are endosymbiotic microorganisms that coexist within different plant species which assist the host in multifarious ways without causing any detrimental effects on the plant well-being. The current study is focused on the bacterial isolates found in the Piper nigrum in vitro culture in the basal MS medium. The growth of these bacterial isolates even after repeated surface sterilization of the explant concludes the nature of these isolates as endophytes and these isolates were identified as Pantoea sp., Luteibacter sp., Herbaspirillum sp., and Agrobacterium sp. through 16srRNA. The endophytes were tested for their potential to aid plant development by assessing the production of Indoleacetic Acid, Ammonia, Hydrogen Cyanide, 1-aminocyclopropane-1-carboxylic acid deaminase, Siderophore, fixation of Nitrogen, solubilization of Phosphate, heavy metal and salt tolerance. Pantoea sp. and Herbaspirillum sp. were found tolerant against salt and heavy metal stress respectively. Based on plant growth promotion assays, Pantoea sp. and Agrobacterium sp. were further selected for metabolomic profiling. The results indicated the effects of isolates on primary and secondary metabolite biogenesis, aminoacyl-tRNA synthesis and amino acid metabolic pathways. The profiling of important metabolites linked to crop development, revealing its metabolic mechanism of plant growth promoting activities facilitated through selected Plant Growth Promoting Bacteria.