Int.J.Curr.Microbiol.App.Sci (2018) 7(1): 2264-2269 2264 Original Research Article https://doi.org/10.20546/ijcmas.2018.701.274 Characterization of Rhizobacteria for Multiple Plant Growth Promoting Traits from Mung Bean Rhizosphere Soumya Routray 1* and Veena Khanna 2 1 Department of Microbiology, PAU, Ludhiana, Punjab-141004, India 2 Department of Plant Breeding and Genetics, PAU, Ludhiana, Punjab-141004, India *Corresponding author ABSTRACT Introduction Among the dozen of pulses, mung bean is the third important pulse crop cultivated in India and accounts for 65% of acreage and 54% of the world’s production (Gowda et al., 2015). It is consumed as whole grain or as dal and valued for its high quality protein that constitutes about 24-25% of total nutrients in seed (Singh, 2010). It is cultivated as sole or inter crop for grain or green manure. Being a leguminous crop, mung bean has the ability to establish a symbiotic relationship with its compatible microsymbiont Rhizobium, setting up of biological nitrogen fixation (BNF) in the root nodules and supply the plant’s needs for nitrogen (Mandal et al., 2009). This Rhizobium-legume symbiosis is the most important plant-bacterial interaction observed in legumes and can fix as much as 30-74 kg N/ha. This legume-Rhizobium interaction is of considerable agricultural importance; it leads to greater quantitative enhancement of combined N in soil thus, reduces the cost of fertilizer for farmers who grow legumes (Dudeja and Duhan, 2005). Besides International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 01 (2018) Journal homepage: http://www.ijcmas.com Soil microorganisms, that flourish in, on or around plant rhizosphere, have tremendous potential to stimulate plant growth by plethora of mechanisms. In this study, 40 rhizobacterial isolates from 15 mung bean rhizospheric soil samples were morphologically and biochemically analysed and tentatively assumed to belong to genera Bacillus (35%), Pseudomonas (55%) and Rhizobium (10%). Ten isolates were evaluated of plant growth promoting (PGP) traits at 35°C viz. production of IAA, GA (Gibberellic acid), flavonoid and siderophore as well as Zn and P solubilisation. Our study showed that all the 10 isolates produce IAA, GA and flavonoid in the range of 6.06-32.13 μg/ml, 109.8-126.3 μg/ml and 68.9-224.7 μg/ml respectively, whereas only 7 isolates were found to be efficient producers of both hydroxamate and catecholate siderophores in the range of 342.8-732.7 μg/ml. Again, all these isolates were potent solubiliser of Zn and P in plate assay. The solubilisation indices ranged from 2.1 to 4.4, 1.4 to 6.0 and 1.8 to 3.1 for ZnO, ZnCO 3 and tri-calcium phosphate respectively. From this study, 3 isolates; S1P1, S4P1 and S13P1 showing superior PGP traits can be executed as effective biofertilizer in field trials for mung bean production. Keywords IAA, GA, Flavonoid, Mung bean, PGP, Rhizobacteria, Rhizobium Accepted: 16 December 2017 Available Online: 10 January 2018 Article Info