Screening and multivariate evaluation of efficient rice phyllosphere and endorhizosphere bacteria for abiotic stress tolerance

Abstract

Abiotic stresses such as salinity, drought, temperature, and pH significantly affect microbial survival and plant microbe interactions in the rhizosphere. In the present study, five efficient bacterial isolates (MPSB 3, MKSB 13, MZSB 7, NFB 11, and MSSB 23) obtained out of total 33 paddy phyllosphere and endorhizosphere bacteria were screened for their tolerance to different abiotic stresses. The isolates were evaluated for salinity tolerance (6% NaCl), drought tolerance using polyethylene glycol (PEG-6000), temperature tolerance at 40 °C, and acidic pH tolerance (pH 5). Among the isolates, NFB 11 exhibited the highest tolerance across most stress conditions, recording 81.4% growth under salinity stress, OD600 of 0.78 under drought stress, OD600 of 0.70 at 40 °C, and OD600 of 0.65 at pH 5. Proline accumulation under PEG stress was also highest in NFB 11 (33.2 µg mL⁻¹), indicating better osmotic stress adaptation. The results suggest that these stress tolerant bacterial isolates, particularly NFB 11, could be promising candidates for the development of microbial consortia for sustainable crop production under adverse environmental conditions.