Biofertilizer Formulation for Yeast–Bacterial Consortia: Synergism Assessment and Optimization of pH, Carrier Media, and Cell Protectant

Biofertilizers consist of beneficial microbes that promote plant growth, and proper formulation is essential to ensure high microbial viability during storage. This study aimed to develop a stable biofertilizer formulation by evaluating microbial synergism, optimizing pH, and assessing different concentrations of molasses and cell protectants. The microbial consortium comprised cellulolytic bacteria (LII.۳-۴), IAA-producing bacteria (LMG ۴۳), nitrogen-fixing bacteria (TBN۱۰), phosphate-solubilizing bacteria (TBN۱۳), cellulolytic yeast (K۱۳), and phosphate-solubilizing yeast (K۱۴). Following the synergism test, pH optimization (۵–۸) was performed, and formulation trials were conducted using molasses concentrations of ۲–۶% combined with three cell protectants (PVP, glycerol, and Gum Arabic ). Viability was monitored using total plate count (TPC) at ۱۰-day intervals for ۹۰ days. All microbes demonstrated growth within the tested pH range, with pH ۶ identified as the optimal condition. The highest consortium growth was observed at ۴% molasses, reaching ۱۰۳۳ CFU/mL. All cell protectants enhanced viability, with Gum Arabic showing the strongest effect, followed by glycerol and PVP. The combination of ۲% molasses and Gum Arabic produced the best formulation, increasing consortium viability to ۱۰³⁸ CFU/mL after ۹۰ days. Statistical analysis at the ۹۵% confidence level confirmed that both molasses concentration and cell protectants significantly influenced microbial viability.

کلیدواژه ها:

Biofertilizers formulation ، Cell protectant ، Molasses concentration ، Synergism ، Yeast-bacterial consortia