Yeast Biofilms Harboring PGPR as a Sustainable Strategy to Improve Soil Ecology and Plant Productivity

This study evaluated the effects of co‐inoculating N‐fixing ( Azotobacter vinelandii ), phosphorus‐solubilizing ( Bacillus methylotrophicus , Pseudomonas putida ), and antimicrobial plant growth‐promoting bacteria ( Lactococcus lactis ) on plant growth and soil fertility by incorporating them into Saccharomyces cerevisiae biofilms used as a carrier. The optimal conditions for biofilm production were determined, and the resulting structures were examined using a scanning electron microscope. A biofilm fertilizer was produced in a biofilm reactor. The microbial fertilizer maintained a viability of ∼10 7 CFU/mL for seven days across pH 4.5–8.5, 0.5%–6% NaCl, and 4°C–40°C. Greenhouse pot experiments with corn plants showed that S. cerevisiae ‐based biofilm fertilizers enhance soil phosphorus, potassium, and organic matter levels, thereby improving soil fertility and microbial activity. When applied in combination with reduced doses of chemical fertilizers, the biofilm formulation resulted in improvements in both soil microbial function and plant performance compared to the untreated control. A key innovation of this study lies in developing a multi‐species biofilm system in which PGPR strains are associated with a pre‐formed S. cerevisiae biofilm matrix, potentially enhancing consortium stability, synergistic interactions, and nutrient transformation under controlled conditions. These findings indicate that S. cerevisiae ‐based microbial biofilm fertilizers represent a promising, sustainable approach that could improve soil fertility, enhance beneficial microbial activity, and reduce reliance on chemical fertilizer inputs.