Isolation, Screening and Molecular Characterization of Multifunctional Plant Growth Promoting Rhizobacteria for a Sustainable Agriculture

The use of PGPR as a multifunctional biofertilizer or biostimulant is an alternative way to prevent soil pollution and preserve agricultural for sustainable economy. In this study, 102 bacterial strains were isolated from rhizospheric soil of different crop fields. Among them, 15 bacterial isolates rich of NPK were selected to screen for PGP activity. It was found that 4 out 15 isolates were able to fix atmospheric nitrogen, 14 could solubilize phosphate and 5 could solubilize potassium. They were further examined for the production of hydrolytic enzymes (amylase, cellulose, chitinase, etc.), plant hormone (IAA) and plant defense substances (HCN, siderophore, etc.). All PGPR isolates were able to produce IAA, siderophore and ammonia while 2 isolates could produce HCN. Among them, 73.33% of selected isolates produced amylase, 80% produced cellulase, 66.67% produced pectinase, 93.33% produced chitinase and β-glucanase. For salt stress tolerance, all the isolates grew well in 5% NaCl while only 4 tolerated 9% NaCl. Among all isolates, 2 have antifungal activity and 5 have antibacterial activity. The best 6 isolates and consortium were tested to promote plant growth in green-gram and maize germination. Seed germination of green-gram and maize was observed the best in Acromobacter insolitus S3 compared with other treatments. Pseudomonas plecoglossicida B3 was found the best in fresh weight for both crops. The highest root formation was observed in Acromobacter insolitus S3 treatment in maize and Enterobacter hormaechei W1 treatment in green-gram.