Bio-inspired core-shell microcapsules enhance plant salinity tolerance by improving stability and survival of non-spore bacteria

Non-spore-forming bacteria can enhance crop salinity tolerance via various strategies, but poor viability during storage and field application limits their use. Inspired by the robust structure of spore dormancy, a core-shell microcapsule consisted of sodium alginate, poly (γ-glutamic acid), and chitosan (APC) is proposed. Using Pantoea alhagi NX-11 as a model, we found that APC encapsulation significantly enhanced bacterial survival during room-temperature storage compared to free cells or alginate beads. This protective effect was further confirmed using two other non-spore-forming strains. The survival mechanism was mainly attributed to the APC-induced metabolic dormancy via suppression of the TCA cycle and oxidative phosphorylation pathways. Furthermore, inoculation with APC-encapsulated NX-11 increased dry weight of rice plant by 24.2% under salt stress in greenhouses and increased grain yield by 15.8% in saline fields, attributing to the enhanced root colonization of NX-11. Overall, this bio-inspired encapsulation strategy provides an effective approach for developing robust microbial inoculants to improve crop resilience in saline soils.