Dry Biofertilizer Development Containing Azospirillum brasilense : A Protective PGCit-Based Strategy for Seed Inoculation

High Resolution Image Download MS PowerPoint Slide The agricultural potential of Azospirillum brasilense is often limited by conventional inoculants, which fail to protect the bacterium from environmental stress. This study developed and evaluated a novel powder formulation by encapsulating A. brasilense in a protective poly(glycerol citrate) (PGCit) and trehalose matrix. PGCit prepared with equimolar monomer ratio and 75 min of reaction was selected for use as a matrix after the optimization study compared residual quantities of monomers and time of reaction. Three drying methods were compared: oven convection, freeze-drying, and spray-drying. All methods yielded high initial viability (approximately 10 8 CFU/g), and the freeze-dried formulation maintained this viability for over 180 days. Furthermore, the freeze-dried formulation enabled significantly higher recovery of the bacteria from coated maize seeds compared to the liquid inoculant. These findings highlight the protective role of the PGCit–trehalose matrix, establishing it as a highly effective dry delivery system for A. brasilense that improves its stability and application potential.