Phytostimulatory effect of indole-3-acetic acid by Enterobacter cloacae SN19 isolated from Teramnus labialis (L. f.) Spreng rhizosphere

A total of 30 morphologically distinct bacterial cultures were isolated from rhizosphere of wild tropical leguminous plant, Teramnus labialis (L. f.) Spreng. These isolates were screened for different plant growth promoting (PGP) traits amongst which a bacterial isolate designated as SN19 identified as Enterobacter cloacae (JQ904624) exhibited maximum IAA production (382.23 µg ml−1 in 0.1% L-tryptophan supplemented medium) along with other PGP traits. The production of IAA was confirmed by TLC and LC–MS/MS analysis. Biological potency of the bacterial IAA was determined using wheat coleoptile bioassay and in vitro root induction of Pluchea lanceolata shoot explants. The seed bacterization and bioinoculation of groundnut (Arachis hypogaea), rice (Oryza sativa), wheat (Triticum aestivum), mung (Vigna radiata) and maize (Zea mays) using this siderophorogenic IAA producer resulted in enhanced seed germination rate and plant vigour under in vivo condition. Thus, our findings indicate that the bacterium Enterobacter cloacae SN19 can serve as a promising plant growth promoting microbial inoculant.