Electrospun PVA nanofibers improve the storage stability of Bacillus amyloliquefaciens fermentation broth

The development of robust, stable microbial formulations remains a major challenge for agricultural use. We report an electrospinning-based formulation that encapsulates Bacillus amyloliquefaciens fermentation broth within poly(vinyl alcohol) (PVA) nanofibers to enhance storage stability and preserve microbial viability. Electrospun nanofiber mats were obtained from PVA formulations containing the fermentation broth, and their morphology, chemical profile, mechanical properties, and microbial viability were evaluated. Morphological, spectroscopic, mechanical, and microbiological analyses demonstrated successful incorporation of the fermentation broth into the PVA matrix and retention of viable Bacillus cells after electrospinning, with comparative estimates of viable cell recovery of 3.3 × 10⁷ CFU cm^- 2 in the electrospun fibers and 8.3 × 10⁷ CFU mL^- 1 in the polymeric spinning solution before electrospinning. Nanofibers stored under ambient conditions for up to one year still yielded viable cells. Collectively, these findings support the potential of electrospun PVA nanofibers as a formulation strategy for microbial stabilization and warrant further investigation toward the development of microbial formulations with improved storage characteristics.