In-vitro evaluation of actinomycetes with plant growth-promoting properties

Abstract

The aim of this study was to evaluate actinomycetes for plant growth-promoting (PGP) traits using in vitro experiments. Actinomycetes were isolated from two different soil rhizospheres and subjected to dual culture experiments in order to determine antimicrobial activity. Subsequently, selected isolates with potent antimicrobial activity were examined further for their ability to biosynthesize indole-3-acetic acid (IAA) and siderophores, solubilize inorganic phosphate, and produce ammonia. Results showed that these strains produced 38.73-211.35 ng/mL IAA in Tryptic Soy Broth (TSB), and solubilized 116.20-319.33 µg/mL inorganic phosphate in National Botanical Research Institute's phosphate growth medium (NBRIP) broth. Additionally, all selected actinomycetes produced siderophores in chrome azurol S (CAS) agar and ammonia in peptone water. Five isolates showed promise as plant growth promoters, with isolates SNN045, SNN056, and SNN059 being the most plausible candidates for agricultural applications.