Sustainable valorization of agricultural wheat bran for Indole-3-acetic acid production and phosphate solubilization by Saccharothrix texasensis MB15
摘要
Indole-3-acetic acid (IAA) production and Phosphate-solubilization represent critical plant growth-promoting traits that enhance agricultural productivity and soil fertility. This study aimed to optimize a wheat bran–based fermentation medium to enhance IAA production and phosphate solubilization by Saccharothrix texasensis MB15, the most promising strain among eighteen Saharan isolates, targeting a ≥ 2.5-fold increase in IAA production and phosphate solubilization through statistical optimization. Using one-factor-at-a-time approach, wheat bran concentration and fermentation duration were identified as key factors influencing IAA production and P-solubilization. Maximum IAA yields were achieved with 50–75 g/L wheat bran after 144 h of incubation. Further optimization through a fractional factorial design highlighted wheat bran, ammonium nitrate (NH4NO3), and sodium chloride (NaCl) as significant medium components. A central composite design coupled with response surface methodology determined their optimal concentrations at 87 g/L, 5.25 g/L and 5.5 g/L, respectively. Under these conditions, IAA production increased by 286% (141.79 µg/mL), and P-solubilization improved by 475% (395.03 µg/mL) compared to the non-optimized medium. These results underscore the potential of wheat bran as a sustainable substrate to optimize the dual-functionality of S. texasensis MB15 in simultaneously producing IAA and solubilizing phosphate, offering a promising strategy for multifunctional biofertilizer development in nutrient-poor environments.