Abstract:
Extremophilic exopolysaccharides (EPS) producing bacteria can play a significant role in plant growth promotion. Seven bacterial strains (BE1, BE2, BE3, BE4, BN1, BN2, BN3) were isolated from Tattapani hot spring, Azad Kashmir, Pakistan. All strains showed EPS production but three strains (BE1, BN1 and BN3) exhibited highest EPS production when screened on P-media. These strains had ability to solubilize phosphate and produce HCN when analyzed for plant growth promoting characteristics. Bacterial strains were used to inoculate globally important cereal crop such as Zea mays. All inoculated seedlings displayed significant increment in germination and growth parameters as compare to control. Alcian blue staining showed good colonization on roots of inoculated Zea mays seedling. Auxin and soluble protein content in Zea mays seedlings were also significantly increased due to bacterial inoculation. The optimum temperature, pH, carbon and nitrogen source for maximum EPS production by selected strains were 28°C, 9, fructose and peptone respectively. Phylogenetic analysis based on 16S rRNA sequencing revealed that bacterial strains BE1, BN1, BN3 were closely related to Ochrobactrum intermedium, Bacillus pumilus and Enterobacter ludwigii, respectively. Fourier-Transform Infrared (FTIR) spectroscopy of EPS produced by strain BN3 indicated the presence of various functional groups like amides, alcohols, carboxylic acids and aromatic compounds. Hence, this study suggested that EPS producing bacterial isolates from extreme environment can be used as biofertilizers to enhance crop yield
