Isolation and identification of plant growth-promoting endophytic bacteria from Eclipta prostrata (L.) L. and its metagenomic evidence through functional annotation

This study reports the isolation, identification and characterisation of plant growth-promoting endophytic bacteria in Eclipta prostrata (L.)L. A total of seven morphologically and biochemically distinct bacterial endophytes, such as Cytobacillus firmus, Bacillus aquimaris, Bacillus cereus, Priestia megaterium, Bacillus thuringensis, Bacillus marsielle and Bacillus oceanisediminis were isolated and identified using 16S rDNA sequencing from the mature, healthy plants of Eclipta prostrata (L.)L. The 16S rDNA sequence data was submitted to the NCBI sequence submission portal with the accession numbers ON406226, ON406240, ON740903, ON406242, ON740903, ON413728 and ON413729 respectively. All the isolates produced IAA, ammonia, siderophore and solubilized phosphate. Three of them except Cytobacillus firmus, Bacillus aquimaris, Bacillus marsielle and Bacillus oceanisediminis were HCN producers. All endophytes were non-producers of ACC deaminase and did not solubilize potassium. The plant growth-promotion activity of the isolates was successfully tested in the seedlings of Vigna radiata and E. prostrata. The whole metagenomic sequencing by Illumina HiSeq followed by functional annotation of genes using KEGG, eggNOGG, nr and CAZY databases generated valid data on genes involved in metabolic pathways like nitrogen assimilation, IAA production, siderophore production, and phosphate solubilisation. • Seven plant growth-promoting endophytic bacteria were isolated and identified from Eclipta prostrata . • All isolates exhibited key growth-promoting traits including IAA, siderophore, ammonia production and phosphate solubilization. • Seedling bioassays in Vigna radiata and E. prostrata confirmed their plant growth-enhancing effects. • Metagenomic functional annotation validated the genetic basis of nutrient acquisition and phytohormone biosynthesis.