Characterization of endophytic bacteria Enterobacter cloacae MG00145 isolated from Ocimum sanctum with Indole Acetic Acid (IAA) production and plant growth promoting capabilities against selected crops

Abstract

The present study is based on morphological, biochemical characterization and 16 s rRNA gene sequencing of an endophytic bacterium OS03 isolated from the stem of Ocimum sanctum and identified as Enterobacter cloacae (Accession no. MG00145). The isolate is a short gram –ve rod able to tolerate 9% of NaCl and can grow at 54 °C, under osmotic stress (40–45% PEG 6000) in the medium. The study focused on the characterization of Indole Acetic Acid (IAA) production under in vitro condition. Isolate OS03 showed better production of IAA at pH 7 (17.807 µg/ml) and 37°C (17.934 µg/ml). The production of IAA increased when the L-tryptophan medium was supplemented with Sucrose (0.5%) and Calcium nitrate (0.1%) as carbon and nitrogen sources, respectively. IAA production was further confirmed by thin-layer chromatography (Rf 0.75 cm) as well as by FTIR and H1NMR analysis. The selected strain OS03 significantly enhanced the growth of four crop plant viz. Oryza sativa (rice), Arachis hypogaea (groundnut), Vigna mungo (black gram) and Brassica rapa var. Toria (toria) in terms of germination index, shoot and root biomass of seedling and seed vigour index in comparison to control.