| Summary: | Abstract Plant growth–promoting endophytic bacteria can enhance crop performance, particularly under environmental stress, through mechanisms such as ACC (1-aminocyclopropane-1-carboxylate) deaminase activity that lowers stress ethylene levels. This study evaluated the ability of the endophytic bacterium Paenibacillus sp. strain MBL_B28 to promote plant growth under normal and saline conditions (100 mM). Paenibacillus sp. strain MBL_B28 produces ACC deaminase (producing 48.4 ± 0.7 nmol/mg/h of α-ketobutyrate) that promotes plant growth. Jute and rice seeds were immersed in a bacterial suspension before being transferred to hydroponic cultures, soil-based systems, and a hybrid of both, and the assessment of various agronomic parameters was conducted to determine statistical significance, ensuring the cross-host applicability of the strain. Under normal conditions at the seedling stage, inoculation with Paenibacillus sp. strain MBL_B28 resulted in better growth of Corchorus olitorius var. O-9897 (jute) and Oryza sativa (salt-sensitive rice var. BRRI dhan28) in the hydroponic system. Under salt stress (100 mM), bacterial treatment markedly enhanced plant survival and growth compared with uninoculated controls, which showed poor viability. Inoculated plants also exhibited increased biomass, chlorophyll content, and proline accumulation, indicating improved stress tolerance. These results demonstrate that Paenibacillus sp. strain MBL_B28 can be suggested as an eco-friendly biofertilizer, as it has the potential to promote host and non-host plant growth through the expression of the ACC-deaminase mechanism in response to salinity.
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