MICROBIAL CAPACITY FOR AUXIN BIOSYNTHESIS: A COMPARATIVE EXPLORATION

Abstract

This study investigates the microbial capacity for auxin biosynthesis, focusing on five agriculturally significant species: Bacillus, Azotobacter, Pseudomonas, Azospirillum, and Rhizobium. Auxin, specifically indole-3-acetic acid (IAA), is a vital plant hormone that regulates various growth processes such as root development and cell elongation. Understanding microbial IAA production is critical for developing sustainable agricultural practices, particularly in the formulation of biofertilizers and microbial inoculants. The research employed both qualitative and quantitative methods to assess the IAA production capacity of these microbes. Qualitative analysis using the Salkowski reagent confirmed the presence of IAA in all strains. Quantitative measurements revealed significant variation in IAA production. Azotobacter exhibited the highest IAA levels at 38.7 µg/mL, followed by Bacillus (31.4 µg/mL), Rhizobium (27.2 µg/mL), Pseudomonas (24.6 µg/mL), and Azospirillum (21.9 µg/mL). These results demonstrate the strain-specific nature of auxin biosynthesis, with certain microbial species exhibiting higher auxin production than others. Furthermore, the production of IAA was found to be closely linked to the availability of tryptophan, a key precursor in the biosynthesis pathway. The results emphasize that the optimization of precursor levels in culture media could enhance IAA production, making microbial strains more efficient for use in agricultural applications. The study suggests that Azotobacter, with its superior auxin production capacity, is a promising candidate for bioinoculant development. These findings contribute valuable insights into the role of plant-associated microbes in hormone synthesis and their potential applications in improving crop growth, root development, and nutrient uptake. Further research, including field trials and genomic analysis, is needed to fully understand the potential of these microbes for sustainable agricultural practices..