Abstract

The study aimed to develop a solid biofertilizer using Bacillus pumilus, focusing on auxin production to enhance plant drought tolerance. Methods involved immobilising B. pumilus in alginate-starch beads, focusing on microbial concentration, biopolymer types, and environmental conditions. The optimal formulation showed a diameter of 3.58 mm +/- 0.18, a uniform size distribution after 15 h of drying at 30 C-degrees, a stable bacterial concentration (1.99 x 109 CFU g(-1) +/- 1.03 x 10(9) over 180 days at room temperature), a high auxin production (748.8 mu g g(-1) +/- 10.3 of IAA in 7 days), and a water retention capacity of 37% +/- 4.07. In conclusion, this new formulation of alginate + starch + L-tryptophan + B. pumilus has the potential for use in crops due to its compelling water retention, high viability in storage at room temperature, and high auxin production, which provides commercial advantages.