Optimized GA ₃ Production by <i>Aspergillus niger</i> and <i>Fusarium fujikuroi</i> : From Low-Cost Fermentation to Agronomic Application

This study aimed to optimize low-cost submerged fermentation for gibberellic acid (GA₃) production using <i>Aspergillus niger</i> LGB-034-2015 and <i>Fusarium fujikuroi</i> Insumicro 175, followed by evaluating the fermentation supernatant in common bean (<i>Phaseolus vulgaris</i>) under field conditions. A factorial design and central composite design were applied to test different concentrations of glucose (10-30 g/L), glycerol (5-15 g/L), and yeast extract (2-6 g/L). Maximum GA₃ production reached 597.03 mg/L (0.60 g/L) for <i>A. niger</i> and 487.23 mg/L (0.49 g/L) for <i>F. fujikuroi</i>. The highest yield per unit of substrate consumed was 550 mg of GA₃ per gram of glucose by <i>A. niger</i>. In the agronomic trials, the supernatant was applied as a foliar spray at 200 mL per plot (four applications during the crop cycle) and compared with untreated controls. The results showed a significant reduction in activity of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and an increase in yield, reaching 44.8 bags per hectare. These findings demonstrate that optimizing GA₃ fermentation with <i>A. niger</i> is a cost-effective approach with practical applications in crop productivity.