This study investigated the effectiveness of two plant growth-promoting rhizobacteria (PGPR) ‎formulations, Bio Arc® 6% WP (BA, Bacillus megaterium) and BECTO Grow Roots® (BGR; ‎Serratia marcescens, Pseudomonas putida, and P. fluorescens). Additionally, it focused on ‎naturally infested soil that had undergone metam potassium fumigation to reduce root-knot ‎nematodes (RKNs), specifically Meloidogyne incognita. It aimed to monitor eggplant response to ‎soil biodiversity changes for 60 days of the experiment under greenhouse conditions. Our data ‎showed that soil fumigation eliminated nematodes and reduced other microorganisms ‎significantly. In sterilized soil, plant fresh root weight significantly decreased after the ‎elimination of soil biota. Moreover, BGR achieved the highest plant growth vigor [fresh root ‎‎(18.48 %), fresh shoot (23.52%), and fresh plant weight (21.03%)], followed by BA [fresh root ‎‎(11.98%), fresh shoot (20.77%), and fresh plant weight (16.38%), respectively]. Plant growth ‎traits increased significantly following the second reinoculation of PGPR after a month. Also, the ‎same data trend was observed in treatments inoculated with RKN+PGPR. Furthermore, BGR ‎treatments exhibited consistent efficacy in controlling nematode infection, maintaining superior ‎vegetative growth compared to BA treatments over time. However, BA treatments displayed a ‎decline in plant growth when faced with repeated nematode infection. The range of gall, egg ‎mass, and second-stage juvenile stages (J2s) numbers diminished after inoculation-infected plants ‎with ‎RKNs and PGPR compared with infected plants alone. Biochemical changes in eggplant ‎roots cultivated in sterilized soil exposed significant enhancement in total sugars, protein, and ‎nonenzymatic antioxidants (flavonoids and phenolic content), with antioxidant activity enhanced ‎upon inoculation of PGPR and RKNs. Oppositely, the levels of enzymatic antioxidants (catalase, ‎peroxidase, and superoxide dismutase) decreased significantly with single and double PGPR ‎application. However, the decline was less pronounced in the BGR treatments than in BA. In ‎contradiction of oxidative enzymes, reinoculated PGPR+ RKN multiplied significantly in ‎reinfested RKNs treatments. Our findings support the use of PGPR combinations, in particular, ‎for preventive inoculation against M. incognita. They also enhance plant growth-promoting ‎factors and stimulate plant defenses against inevitable soil reinfestation following soil fumigation.