Open Access : IJBNHY : 2278-778X Original Research Article International Journal of Bioassays *Corresponding Author: Dr. Kanti Prakash Sharma, Department of Biological Science, College of Arts, Science & Humanities (CASH), Mody University of Science & Technology, Lakshmangarh, Sikar 332311, Rajasthan (India), India. E-mail: kantipsharma@rediffmail.com http://dx.doi.org/10.21746/ijbio.2016.12.001 pg. 5118 Molecular characterization of potential salt tolerant bacteria for soybean growth promotion Anukool Vaishnav 1,2 , Sarita Kumari 1,2 , Shekhar Jain 1,2 , Devendra Kumar Choudhary 2 , Kanti Prakash Sharma 1* 1 Department of Biological Science, College of Arts, Science & Humanities (CASH), Mody University of Science & Technology, Lakshmangarh, Sikar 332311, Rajasthan, India. 2 Amity Institute of Microbial Technology (AIMT), Block ‘E-3’, 4 th Floor, Amity University Campus, Sector-125, Noida-201303, Gautam Buddha Nagar, UP, India. Received: October 16, 2016; Accepted: November 23, 2016 Available online: 1 st December 2016 Abstract: Salinity is a major limiting factor for soybean crop productivity. To enhance the tolerance of soybean against salt stress, it is essential to understand the diversity of microbiota harboured by soybean rhizosphere. Earlier studies have demonstrated that local adaptation of plants to habitat imposed stresses is driven by their closely associated microbes. The present study aimed to isolation and characterization of salt tolerant rhizobacteria with respect to their functional plant growth promotion ability. A total of 43 bacterial isolates were recovered from soybean rhizospheric soil grown in Bundi district, Rajasthan, India. Out of them, one bacterial isolate strain AU was found to tolerate 10% NaCl stress and significantly enhanced soybean seedlings growth under 100mM NaCl condition. Molecular phylogenetic analysis placed this isolate closely to Pseudomonas simiae OLi T with 99.93% similarity. Molecular characterization of functional genes revealed that AU bacterium possessed genes like IaaM (IAA production), g6pd (Pi-solubilization) and sid (siderophore production). Here, we show that soybean rhizosphere possessed a salt tolerant plant growth promoting bacterium strain AU, which may have impacts on alleviation and tolerance of salt stress in legume plants. Key words: Genes; Plant growth promoting rhizobacteria; Salinity; Soybean Introduction Abiotic stresses are serious environmental factors in arid and semi-arid climatic area that restrict the growth and productivity of plants worldwide. Among these stresses, soil salinity contributes a major proportion in destruction of cultivated land area and reduction of crop productivity. Various number of salts e.g. sodium chloride (NaCl), sodium sulphate (Na2SO4), sodium nitrate (NaNO3), magnesium sulphate (MgSO4), magnesium chloride (MgCl2), potassium sulphate (K2SO4), calcium carbonate (CaCO3) etc. could be dissolved in saline soil, although NaCl causes most of the salt problems for higher plants in nature. Today, it is big challenge to increase the efficiency and sustainability of global agriculture system. Because this system is regularly marked by scarcity of water resources, environmental pollution and increased salinization of soil and water. These challenges create continued poverty and food insecurity by which people become chronically malnourished. Many resident micro-flora of stress environment perform all functions of life for survival of their own and associated biological entities. Some genera, like Bacillus, Paenibacillus and Pseudomonas are actively being used to alleviate abiotic stresses (Choudhary et al., 2015). In saline environment, halophilic bacteria and their metabolites have exhibited many potential which are suitable for vast agricultural, industrial and environmental applications. The successful restoration of plant growth under salinity condition after inoculation with plant growth promoting rhizobacteria (PGPR) provides the basis for a suitable alternative to improve crop growth and yield in saline soils. These PGPRs are mostly present in near the roots due to presence of root exudates secreted by plants and used as nutrient source by them. There is clear evidence that a diverse group of root-associated microbes is essential for promoting plant adaptation to salinity (Arora et al., 2013; Shrivastava et al., 2015; Egamberdieva et al., 2015). Beneficial effect of PGPB under salinity has been related to hydraulic conductance, osmolyte accumulation, sequestering toxic Na + ions, maintaining higher stomatal conductance and photosynthetic activities (Dodd et al., 2012).