A metagenomic survey of the rhizosphere bacterial community of P. longum from the herbal garden, Dayalbagh Educational Institute (D.E.I), Agra, India.

The rhizosphere of medicinal plants harbors complex microbial communities that plays a key role in nutrient cycling, plant growth, and environmental adaptation. Piper longum L., an important medicinal plant, remains poorly explored with respect to its rhizospheric microbiome. In this study, rhizospheric soil samples of P. longum were collected at the spike stage from the Herbal Garden of Dayalbagh Educational Institute, Agra, India, and analyzed using metagenomic approach. Soil physicochemical analysis revealed a neutral to slightly alkaline pH with moderate nutrient availability, indicating favorable conditions for microbial activity. High-throughput Illumina sequencing generated ~ 19.94 million paired-end reads (~ 5.92 Gb), which were assembled into 97,432 scaffolds (52.26 Mb total length), and 45,876 protein-coding genes were predicted. Taxonomic profiling revealed dominance of Proteobacteria (42%), followed by Actinobacteria (13.9%), Thaumarchaeota (13.16%), Chloroflexi (8.21%), and Acidobacteria (7.28%). At the genus level, Nitrososphaera was the most abundant (23.58%), with Candidatus Nitrososphaera gargensis as the predominant species (11.21%), indicating an active microbial community of ammonia-oxidizing archaea involved in nitrogen fixation. Functional annotation using COG, KEGG, Pfam, GO, and FIGfams databases revealed enrichment of genes associated with amino acid transport and metabolism, carbohydrate metabolism, energy production, and environmental adaptation. Overall, this study provides the first metagenomic baseline of the P. longum rhizosphere microbiome and highlights its potential role in nutrient cycling and sustainable cultivation.