Biological conversion of agricultural wastes into indole-3-acetic acid by S. lavenduligriseus BS50-1 using response surface methodology (RSM)

Abstract Agricultural waste can be used as an alternative source for plant growth regulator (PRR) biosynthesis by microorganisms. Actinomycetes are an important group of soil microbes that play a significant role in the soil as plant growth-promoting rhizobacteria (PGPR) as well as biofertilizers. This study focused on the development of a low-cost medium based on bagasse to improve indole-3-acetic acid (IAA) production by S. lavenduligriseus BS50-1 using response surface methodology (RSM). Among thirty-four actinomycete strains, S. lavenduligriseus BS50-1 exhibited the highest IAA level under the selected medium. RSM based on central composite design (CCD) was used to optimize the appropriate nutrients for IAA production. Thus, glucose hydrolysate and L-tryptophan concentrations of 3.55 g/L and 5.0 g/L were optimal factors improving IAA production from 37.50 µg/mL to 159.47 µg/mL within 168 h. This study is the first to report the potential application of leftover bagasse as raw material for the cultivation of actinomycetes as an efficient IAA producer to promote plant growth.