In the present study a new PGPR formulation was optimized for the suitable carrier, pH and weather conditions towards the growth response of brinjal plants at 30 days and improving soil fertility. The effect of inoculation of different carrier based PGPR formulations on soil available plant nutrients, population size of PGPR and plant growth promotion of brinjal seedlings at 30 days in green house trial was significant at p˂0.05. Good result was observed with Humus based PGPR; 578.24 ± 1.14 KgNha-1, 648.26 ± 1.24 KgKha-1, 38.34 ± 1.32 KgPha-1, 15 ± 2 × 106cfu/g soil Nfb, 16 ± 3.61 × 106cfu/g soil Psb, 15.67 ± 2.08 × 106cfu/g soil Ksb, 26.38 ± 0.56 shoot length, 8.22 ± 0.60 root length and 6.20 ± 1.50 number of leaves. H-PGPR was found to be effective on soil available plant nutrients; 578.28 ± 1.14 KgNha-1, 38.40 ± 1.28 KgPha-1, 648.32 ± 1.20 KgKha-1, population size of PGPR; 15.67 ± 2.08 Nfb, 16.67 ± 3.22 Psb, 16.33 ± 2.52 Ksb (106cfu/g soil) and plant growth promotion; 26.62 ± 0.85 shoot length, 8.24 ± 0.68 root length and 6.60 ± 0.55 number of leaves at pH 7.0. Significant result was observed with H-PGPR on summer season when compared to winter and rainy season (p˂0.05).From this work, it is concluded that PGPR grows and works better in summer season at pH 7.0 and humus as the carrier.