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Abstract

Free-living actinobacteria were isolated from a limestone mining spoil soil located at Mawsmai in Meghalaya, India. The actinobacterial colonies obtained were screened for plant growth promoting properties based on their ability to produce indole-3-acetic acid and siderophores, their ability to solubilize phosphate and their ability to fix atmospheric nitrogen. Fifteen isolates thirteen of which were Streptomyces were found to produce indole-3-acetic acid above 15µg ml -1 . Eight isolates were found to solubilize phosphate above 350µg ml -1 . Out of these, three were Streptomyces and the remaining five were non-streptomycetes. Ten isolates which were all Streptomyces were found to produce siderophores with halo diameter greater than 25mm. 65% of the isolates, 93% of which were Streptomyces showed the ability to fix atmospheric nitrogen.Therefore, free-living limestone actinobacteria from Meghalaya more importantly Streptomyces showed plant growth promoting potential and some of them warrant further investigation through their interaction with plant systems and to find out if plants can benefit through such plantactinobacteria interactions in vivo.