Metagenomic Analysis to Assess the Impact of Plant Growth-Promoting Rhizobacteria on Peanut ( Arachis hypogaea L.) Crop Production and Soil Enzymes and Microbial Diversity

Peanut production could be increased through plant growth-promoting rhizobacteria (PGPR). In this regard, the present field research aimed at elucidating the impact of PGPR on peanut yield, soil enzyme activity, microbial diversity, and structure. Three PGPR strains (Bacillus velezensis, RI3; Bacillus velezensis, SC6; Pseudomonas psychrophila, P10) were evaluated, along with Bradyrhizobium japonicum (BJ), taken as a control. PGPR increased seed yield by 8%, improving the radiation use efficiency (4–14%). PGPR modified soil enzymes (fluorescein diacetate activity by 17% and dehydrogenase activity by 28%) and microbial abundance (12%). However, PGPR did not significantly alter microbial diversity; nonetheless, it modified the relative abundance of key phyla (Actinobacteria > Proteobacteria > Firmicutes) and genera (Bacillus > Arthrobacter > Pseudomonas). PGPRs modified the relative abundance of genes associated with N-fixation and nitrification while increasing genes related to N-assimilation and N-availability. PGPR improved agronomic traits without altering rhizosphere diversity.