Pickering Emulsion for Enhanced Viability of Plant Growth Promoting Bacteria and Combined Delivery of Agrochemicals and Biologics

Abstract

Non-sporulating plant growth-promoting bacteria (PGPB) are widely underutilized in the bio-based agroindustry due to difficulties in maintaining viability without spores. A unique approach is presented to prepare PGPB-based green formulations by integrating Gram-negative, nonsporulating PGPBs: Pseudomonas simiae (Psi) and Azospirillum brasilense (Abr) into cellulose acetate stabilized Pickering emulsions. The bacteria show enhanced survivability within the emulsions without any nutrient supply after 4 weeks of storage with Psi and Abr showing 200% and 500% increases respectively relative to non-nutritive saline (1X PBS) control. Transcriptomics suggest that lysed bacteria from the emulsification process act as crucial nutrient sources, thereby boosting bacterial survival rates. Moreover, these PGPBs maintain survival even in the presence of the model pesticide fluopyram, with Pseudomonas simiae concentration showing a twofold increase after 1 month of storage while still preserving the efficacy of fluopyram against target pests. This robust survival trait among nonsporulating PGPB marks a notable advancement in developing formulations tailored specifically for these organisms. It underscores their untapped potential for practical applications in agricultural and environmental contexts. Furthermore, the emulsions enable simultaneous loading of biologicals (PGPBs) and agrochemical pesticides without compromising performance, thus offering the promise of a single loading platform to deliver multiple actives.