Determination of Plant Growth Promotion and Antimicrobial Activity Potential of Identified Actinobacteria from Kula Geopark

Actinobacteria, known as producers of bioactive compounds, also help enhance plant growth through nitrogen fixation, ammonia, siderophore, and indole-3-acetic acid (IAA) production, phosphate solubilization, and phytopathogen suppression. In this study, antimicrobial activity and the plant growth-promoting potentials of 34 Actinobacteria isolated from the Kula Geopark were investigated. Among these isolates, eight members of Amycolatopsis (KG3, KH8, KH9, KR1, KR2, KR3, KR6, KR12) performed ammonia production, nitrogen fixation, IAA production, phosphate solubilization, and siderophore production, while also exhibiting significant antimicrobial activity against eight different pathogens. Additionally, five isolates of the genus Kribbella (KS52, KS86, KS88, KS95, KS96) performed ammonia production, nitrogen fixation, IAA production, phosphate solubilization, and siderophore production. The Actinomadura sp. KS37 isolate, which was identified for its siderophore production, is also one of the two isolates that exhibit the broadest microbial activity spectrum, showing inhibition zones against nine pathogens. Another isolate with a broad spectrum, Micromonospora sp. KC97 demonstrated antimicrobial activity against nine pathogens. These findings indicate that the Actinobacteria from Kula Geopark have significant potential for promoting plant growth (PGP) and exhibiting antimicrobial activity.